4. THE UNIFORMITY PRINCIPLE AS A TOOL IN THE
SERVICE OF REALISM IN RELATION TO THE PAST
Geology focuses mainly on geological phenomena and
processes that occurred in the past.2
The preoccupation with geol-
ogy as a historical science3
actually requires a belief in realism in
relation to the past.4
The geologist must believe in the existence
of geological events that occurred in the past and in his capacity
to learn about them as they actually occurred. This is a basic as-
sumption required of any person who undertakes to study past
physical events. In other words, in spite of the fact that the past
is not accessible to direct geological research, geologists believe
in its existence, in its independence on the thought process of
the geologist, and in his or her ability to understand it as it actu-
ally existed. On the one hand, geologists distinguish between the
study of present sources (evidence and geological observations in
the present) and past geological events. On the other hand, they
do not regard this as a problem: They do not see any problems
with the transition from the present to the past. This realistic ap-
proach interprets the expression “discovering the past” literally
and entails the belief that the past can be discovered as it actually
happened. Geologists usually accept this approach and regard it
as intuitive and obvious.5
Geohistory without belief in realism in relation to the past
is scientifically irrelevant, as there is no reason to attempt to
study the past unless one believes in the possibility of discover-
ing it and getting to know it.6
However, this attitude indicates
that geologists entertaining a realistic approach consciously or
unconsciously assume that the time arrow is one-directional and
irreversible.7
This means that, contrary to the laws of physics
and like the second law of thermodynamics, geology, as the sci-
ence of the history of Earth, assumes that the direction of the
time arrow is from past to future, that is, asymmetric in rela-
tion to the reversal of the direction of time (irreversibility of the
time arrow).8
The realistic geologist claims that events that happened in
the past belong to the past that cannot return, and that the geol-
ogist has no causal influence on them. On the other hand, since
he observes present events directly, he is able to understand
and to explain the past, on the basis of causal relations and the
uniformity principle. As a matter of fact, he claims that the
past always precedes the future, and that the future events are
causally influenced by past events—namely that causality is
one-directional from past to future.9
The causes have occurred
in the past, and the results occur in the present or in the future;
therefore, the cause must always precede the result. One may
argue that the assumption of asymmetry and irreversibility of
the passage of time is a more basic assumption preceding the
assumption of causality. In other words, a geological realist
cannot present causal arguments concerning geological events
that happened in the past without assuming the direction of the
time arrow.
In conventional historical sciences (human history, archae-
ology, etc.), realism in relation to the past assumes at least three
time arrows, as follows:
1. the metaphysical time arrow, determining the order of events
from past to future10
;
2. the epistemic time arrow, according to which the past is
closed, and there is no epistemic access to it except by means
of assumptions referring to the present11
; and
3. the causal time arrow, according to which every result in the
present has causes rooted in the past and these causes pre-
cede the results.
In addition to these time arrows, for historical sciences, such
as geology, that deal with natural phenomena, the relevant sci-
entists have to rely on the thermodynamics time arrow, in order
to provide a scientific foundation to the historical explanation.12
On the face of it, this worldview is intuitive, naïve, and well
adjusted to common sense. Geologists derive from it the basic
assumptions on which their day-to-day work is based. However,
close examination reveals its metaphysical aspect, and the dif-
ficulty to realize it in the framework of geohistorical reasoning.
2
For more details, see, for example, Kitts (1978) and Kleinhans et al. (2005,
p. 290–292).
3
It should be noted that this essay mostly concerns geology as a historical sci-
ence and the geologist as a reconstructor of past environmental conditions from
specific outcrops and cores. The attributes of geology as a historical science will
be displayed later herein.
4
Philosophic consideration of realism and the reality of past can be found in
Sober (1988), Dummett (1978), Turner (2007), and Weinryb (1987).
5
Here, I am referring to a particular type of truism. For more details, see Kitts
(1978, p. 219).
6
This attitude is not confined to geology but is common to all historical sci-
ences. However, before tackling the uniformity principle, the most fundamental
principle of geology, I think it appropriate to describe the geologists’ conception
of realism in relation to the geological past of Earth. This conception can be
regarded as deriving from the uniformity principle itself, and it justifies, in a cer-
tain sense, referring to geology as a historical science. I would like to emphasize
that defining the geologist as a realist in relation to the past does not mean that
there is no chance of finding an idealist among geologists. My argument is not
merely philosophical, but based on geological textbooks in which the realistic
approach of modern geologists is evident. For example, a quotation from Hutton,
regarded as the father of modern geology, in his book The Theory of the Earth
(Hutton, 1795, p. 280–281) runs as follows: “A theory of the earth which has for
object truth, can have no retrospect to that which had preceded the present order
of this world; for, this order alone is what we have to reason upon.”
7
Below, I maintain that this assumption is based, among others, on the sec-
ond law of thermodynamics and on Boltzmann’s “past hypothesis,” i.e., my
argument is that realism in relation to the geological past is partly based on
statistical mechanics in general and on the second law of thermodynamics in
particular. This fact indicates that, on principle, it is possible to reduce geology
to physics.
8
Consideration about development of some conceptions of time in geology can
be found in Overton (1994) and Gould (1987).
9
More in-depth discussion regarding this causality would be fulfilled later.
10
In this arrow, we can include the psychological arrow that relies on the psycho-
logical feeling of the flow of events from the future to the past.
11
In this respect, this arrow can be linked to the mutability arrow, according to
which the future is subject to change, but the past is not.
12
As I will specify later, modern geologists assume a progressive picture of the
world (evolutionism) and the uniformity of law and process. These two assump-
tions connect the geological perception to the second law of thermodynamics,
or in other words to the thermodynamic time arrow.
20 G. Kravitz
5. The main difficulty lies in the facts that the past is inaccessible
and independent, and that there is no necessary logical connec-
tion between the past and the present. The difficulties cannot be
solved in the physical world around us on account of the pre-
viously mentioned existence of the time arrows (the thermo-
dynamic, the causal, the epistemic, and the metaphysical). The
past cannot be observed directly, and, although geologists talk
of geological events that have happened in the past, they have
never observed them directly. Moreover, there is an even deeper
gap—the gap between past and present. Accessibility to sources
and evidence is rooted in their availability in the present, but past
events are inaccessible, since they are part of the past. Can this
disparity be resolved? If the objects of geological inquiry are
cognitively independent, is it at all possible to know them? On
the other hand, if it is possible to know them, how can one argue
that they are independent?
Bertrand Russell famously expressed his skeptical point
of view about the gap between past and present (Russell, 1921,
p. 159–160) as follows:
There is no logically necessary connection between events at different
times; therefore nothing that is happening now or will happen in the
future can disprove the hypothesis that the world began five minutes
ago. Hence the occurrences which are called knowledge of the past are
logically independent of the past.
The geologist learns about the occurrence of natural
processes in the past by means of observations conducted in the
present. These are accessible on a perceptive level and can be
perceived directly by his senses. For instance, he can map the
rock in the field, observe it from space, photograph the rocks
at different wavelengths, drill in the depths of Earth, examine
the magnetic attributes of the rock and its density, carry out a
chemical analysis of the rock, carry out an isotopic analysis of
the rock and the fossils in it, etc. The picture that emerges with
regard to past geological events is quite different. On account
of the one-directional time arrow and the fact that the past can
never return, past events are not accessible and cannot be per-
ceived directly by the geologist, and he is unable to know them
for certain. Since this is the situation, geologists are content to
learn about them indirectly, on the basis of an artificial timeless
assumption (the uniformity principle), allegedly bridging the
gap between arguments concerning past events and those con-
cerning present events. In other words, the geologist must learn
about the past indirectly by means of its remains—traces left by
geological processes that occurred in the past. Indirect learning
is based on logical-causal arguments and a basic assumption of
timelessness—the uniformity principle, on the basis of which
the geologist makes inferences from observed events in the pres-
ent to unobserved events of the past, i.e., from the known to the
unknown.13
It can therefore be said that the geologists’ knowledge of
the past is based on pretheoretical assumptions, often of a meta-
physical nature, not susceptible to logical or empirical proof.14
In
a certain sense, they are products of the geologists’ imagination
(artificial). Thus, geologists are realists in relation to the past,
both consciously (they believe that the events of the past are in-
dependent of the geologist’s thinking; nevertheless, they are able
to discover them), and latently (they do not actually discover
the past, but rather construct it). To state this more exactly, by
assuming the uniformity principle, the past becomes dependent
on the geologist’s thinking, and in this sense, he can be said to
construct it rather than discover it. This principle serves realism
in relation to the past, and, by artificially abolishing the logical
independence of both the past and the present, it enables a reduc-
tion from the present to the past.15
Nevertheless, this creates an
absurd situation: On the one hand, geologists believe in realism
in relation to the past, but in practice (probably not consciously),
they make metaphysical assumptions that are, in a certain sense,
unrealistic.
In this situation, the problem of the inaccessibility of the past
remains unsolved, and the uniformity principle, as I will show
later, does not help. In spite of this, it should be remembered that
the uniformity principle is a scientific method uniting geology
with other natural sciences—physics, chemistry, biology, etc.—
thereby creating a more sound and wider scientific basis for it.
In other words, geohistorical thinking derives, in a certain sense,
from the laws of physics,16
and this is confirmed by the different
elements of the uniformity principle (to be specified later herein).
This is probably one of the reasons that geologists do not worry
about their realistic worldview, since the same worldview is also
accepted in physics, and therefore the questions and difficulties
presented here must necessarily be solved in the context of basic
theories of physics and other natural sciences.
In addition, it should be remembered that whoever seri-
ously doubts realism in relation to the geological past, actu-
ally casts doubt on human cognition in general. In principle,
every kind of cognition, not only geological cognition, must
overcome the gap between past and present. For instance, on
the basis of a physical fact according to which light moves at a
constant velocity, one might argue that direct visual observation
does not exist in reality. Everything that we see around us is the
past. Direct cognition continues for some time. This perceptual
process has a natural time limit that at least takes time from the
moment the rays of light pass from the object perceived through
14
We are referring, for instance, to the uniformity principle in nature, which,
as Hume has already shown, is a specific principle that cannot be logically and
empirically justified. There is no logical obligation to assume the uniformity of
nature, and this argument cannot be empirically confirmed, since any such at-
tempt would have to assume this very argument as a basic assumption.
15
The uniformity principle appears to bridge the gap between past and present
and thus represents, in a certain sense, the reductionist approach regarded by
some modern philosophers as an antirealistic approach (see, for instance, the
discussion of the subject in Dummett, 1978, p. 359).
16
This standard concept is accepted by most geologists and science philoso-
phers. For consideration about this issue, see, for example, Schumm (1998,
p. 2–3) and Kitts (1977, p. xi).
13
The use of causal explanations and logical arguments that enable one, by
means of evidence from the present and universal timeless generalizations, to
learn about the geological past and reconstruct it enhances the argument con-
cerning geologists’ belief in realism in relation to the past.
Thermodynamics time arrow and the logical function of the uniformity principle in geohistorical explanation 21
6. our eyes until the stimulus reaches the brain. This means that
there is a natural (physical) gap between the occurrence of the
real event and its perception. This gap cannot be bridged within
the limits of our physical nature, and it is therefore valid for any
kind of human cognition and not particularly for geohistorical
cognition. This is probably another reason why geologists do
not attach great importance to it and see no difficulty in the
application of the uniformity principle and the passage from
certain geological events to others that happened in a different
geological time.
ELEMENTS OF THE UNIFORMITY PRINCIPLE
As stated already, the uniformity principle serves as an arti-
ficial methodological tool, the main function of which is to apply
the realistic belief of the geologists concerning the geological past
of Earth. Nevertheless, difficulties in accurately describing it and
defining it have cropped up throughout the history of geology.17
Many of the definitions suggested were too general or not sub-
stantial enough, and these provided reasons for many arguments
(Hubbert, 1967, p. 4). As a result, a lot of confusion arose around
the concepts of actualism and uniformitarianism (Simpson, 1975,
p. 271).18
To conclude, the concept of uniformitarianism was not
properly understood by geologists, and this caused many errors
in modern geological literature (Austin, 1979; Shea, 1982). In
order to explain the confusion and clarify the concepts correctly,
some philosophers/geologists distinguished between two central
concepts of uniformitarianism (Hooykaas, 1959; Gould, 1965;
Visotskii, 1961):19
1. substantive uniformitarianism, or simply uniformitarianism,
and
2. methodological uniformitarianism, or simply actualism.
Substantive uniformitarianism claims that geohistorical uni-
formity or identity exists between present and past geological
events.20
This is actually an ontological argument (that can be
subjected to empirical examination), according to which there is
uniformity (or identity) in the force, rate, and type of geological
causes and effects throughout deep geological time—namely, the
phenomena (causes, processes, and effects) do not change their
force, rate, and type in the course of time.
In contrast to substantive uniformitarianism, methodological
uniformitarianism (actualism) is a methodological process that
enables us, by means of an analogy,21
to know and explain the
geological past of Earth based on geological events observed in
the present. As a matter of fact, actualism is based mainly on
empirical observations concerning the types of causes and the
forces of the geological phenomena at present. On the basis of
these observations, geologists make inferences about types of
causes and their force in the past. This methodology is based on
the uniformity of the laws of nature in time and space.22
In other
words, in contrast to substantive uniformitarianism, which con-
stitutes an ontological argument or a principle pertaining to the
actual world, actualism is merely an epistemological methodol-
ogy enabling geologists to study the geological past of Earth by
means of geological observations in the present.23
The confusion of actualism with uniformitarianism had
already begun at the time of Lyell, who, overtly or covertly, united
methodological uniformitarianism and substantive uniformitari-
anism24
and included four different elements in a single unifor-
mity principle (Gould, 1987, p. 117–126):25
1. The uniformity law—The laws of nature do not change
(static and uniform) in time and space. This is not a statement
concerning Earth, but it is an a priori statement of the scientific
method. Without this assumption, geological research would not
have been possible.26
2. The uniformity of processes or actualism—Geological
phenomena that occurred in the past may be explained by means
of geological causes and factors operating in the present.Accord-
ingly, the laws of geology act over time by means of the forces
acting in the present. Thus, if we wish to reconstruct the geologi-
cal past of Earth, we must rely on active processes forming the
face of Earth in the present. This too is not a statement pertaining
17
Regarding difficulties to define the uniformity principle, see, for example,
Austin (1979) and Shea (1982).
18
As we shall see later herein, Lyell himself regarded the uniformity principle
in a general and complex manner, including the consensus with regard to the
method and ontological argument pertaining to complete uniformity in nature
(Gould, 1987, p. 105). Apparently, this is what caused the confusion among
geologists/philosophers in the past and in the present.
19
A similar terminology was suggested by Austin (1979), Gould (1984), and
Rudwick (1971). Some scientists disagree with this terminology and claim that
it is insufficient for modern geological research (Şengör, 2001, p. 38). I do
not intend to discuss this argument in this paper but accept the terminology as
presented by Gould (1984), which is accepted to this day by the majority of
geologists.
20
The term “geological event” includes (1) the causes and factors that brought
about the geological phenomena, (2) the geological process (the activating
mechanism) of the phenomenon, and (3) the effects caused by the geological
process.
21
As in other historical sciences (see, for instance, Gifford-Gonzalez, 1991,
p. 215–226), the process of inference by means of analogies is often used in
geology (for more in-depth discussion regarding this issue, see Baker, 2013). In
this process, the researcher observes processes occurring in the present and, on
the basis of direct observation, infers the causal relations between them. After
that, he observes the historical objects—by direct observation of the remnants
of the past—and compares them to contemporary objects. This comparison
enables him to make inferences concerning causal relations of processes that
occurred in the past and through them to reconstruct the causes of the effects
observed in the present.
22
About the role of methodology in Lyell’s theory, see Laudan (1982).
23
About actualism as an epistemological argument and uniformitarianism as an
ontological argument, see Gruza and Romanovsky (1975).
24
Some geologists claim that Lyell united the concepts on purpose as part of
his tactics. First, he united the concepts under the name “uniformity” and later
argued that geologists must accept substantive uniformitarianism because their
practice is based on methodological uniformitarianism (Gould, 1984, p. 10).
25
For further discussion of this point, see Rudwick (1972, p. 164–217), Gould
(1984, p. 11–12), Virgili (2007, p. 575–577), Camardi (1999, p. 537), Austin
(1979, p. 32), and Anderson (2007, p. 451).
26
Actually, this argument is valid for all scientific disciplines and not solely for
geology. This is an a priori assumption, but the lack of it would preclude all
science and any explanation of the physical reality. Lyell, an exemplary sci-
entist, introduced this element into geology and placed it on solid scientific
foundations.
22 G. Kravitz
7. to Earth, but an a priori statement pertaining to a process or a
scientific method.27
3. The uniformity of rate or gradualism—The rate of change
of geological processes is slow, stable, and gradual and contin-
ues over time. This is an empirical statement pertaining to Earth
(with regard to the uniformity of the rate, speed, and force of
geological processes) that can be tested empirically.
4.The uniformity of state or nonprogressionism—The history
of Earth does not have a definite direction (vector). The geological
state of Earth changes in cycles and does not really progress in
any direction. The adherents of this theory refer to the uniformity
of state on the face of Earth. Earth always looks and behaves in
the same way over long geological time; in other words, Earth is
in a dynamic steady state. This is an empirical statement accord-
ing to which the face of Earth has not changed substantially since
its creation, and it has remained in the same dynamic balanced
state. One moment is identical to any other moment. Species may
change but the average complexity of life endures forever.
The disputes arose around these elements, especially around
the degrees of uniformity, i.e., four different possible types of
change reflected in geological phenomena over time (Hooykaas,
1959, p. 3–32):
1. Geological phenomena that happened in the past differed in
type and were more energetic than geological phenomena
happening in the present.
2. Geological phenomena that happened in the past differed in
type but not in energy from geological phenomena happen-
ing in the present.
3. Geological phenomena that happened in the past differed in
energy but not in type from geological phenomena happen-
ing in the present.
4. Geological phenomena that happened in the past differed
neither in type nor in energy from geological phenomena
happening in the present.
The first two elements of the uniformity principle, as shown
previously, are methodological characteristics of methodological
uniformitarianism that cannot be subjected to empirical proof
and are actually versions of more basic principles—the principle
of induction and the principle of simplicity.28
Without these prin-
ciples, any geological explanation is not possible. In geology,
as in any other scientific discipline, scientists must assume that
uniformity of the laws of nature and the laws of geology exists.
This assumption enables one to make an analogy by stating that
the geological causes active in the present are identical to those
that were active in the past. Such an analogy makes it possible to
construct the geological past of Earth, on the basis of geological
observations of processes in the present. On the other hand, the
last two elements deal with the actual state of Earth (substantive
uniformitarianism) and can be empirically proved or refuted, on
principle. Therefore, most of the disagreements between geolo-
gists from the time of Lyell until this very day refer to them.
In the course of the history of geology, most of the arguments
of substantive uniformitarianism have been refuted (Gould, 1965,
p. 226), or rather the elements of uniformity of rate and uniformity
of state were refuted on theoretical and empirical grounds (Austin,
1979, p. 33–40). Lyell himself, at the end of his professional career,
accepted Darwin’s theory of evolution on the basis of empirical-
paleontological findings and renounced the idea of uniformity of
state.29
This renunciation introduced a historical element into his
theory and emphasized the difference between himself and Hut-
ton. On the basis of this renunciation, Lyell promoted the objective
understanding of the history of Earth in terms of a series of chrono-
logical events over a long time period. By renouncing uniformity of
state, he actually rejected the notion of nonprogressionism and ac-
cepted evolutionism (Gould, 1984, p. 14). Of no lesser importance
is the fact that Lyell’s work was greatly influenced by the work of
Kelvin30
concerning the laws of thermodynamics in general, and
the second law of thermodynamics in particular. Kelvin is known
to have rejected the theories of Hutton and Lyell concerning the
uniformity of rate and the uniformity of state because they refuted
the second law of thermodynamics (Dott, 1998, p. 17). This rejec-
tion was in line with Darwin’s evolutionism, and on this account,
Lyell renounced the element of uniformity of state, and, therefore,
this element was abandoned by geologists in the nineteenth cen-
tury, replaced by evolutionary geology (Austin, 1979, p. 33).31
However, Lyell never abandoned the element of uniformity
of rate. He assumed that neither the internal energy of Earth nor
the geological forces (causes) have changed and lessened over
time. Therefore, all the disputes from the nineteenth century to
this very day, concerning the uniformity principle, have been
about this element. Those who referred to the age of Earth in
terms of thousands of years required speedy processes and mighty
forces in order to explain the present geological state of Earth. On
the other hand, those who referred to the age of Earth in terms of
millions or billions of years claimed that geological processes
were gradual, extremely slow, and uniform over deep geological
time.32
Finally, the dispute was resolved on an empirical basis;
27
This component is based on—and in certain respects derived from—the first
component of the uniformity of law. Without assuming uniformity in nature,
one cannot talk of uniformity of geological processes, based on and explained
by the laws of nature. The metaphorical sentence “the present is the key to
the past” refers to the two components together. To state it differently, when
Lyell mentions the uniformity of causes and forces, he was not referring only
to physical and chemical uniformity of the material, but also to the uniformity
of processes in the course of the interaction between material and energy that
produces specific geological events. As a matter of fact, a certain hierarchy is
discernible between the various components of the uniformity principle. The
laws of physics occupy the top of the pyramid, and all the other components
derive from them in an orderly way (Austin, 1979, p. 323).
28
Explanation of this argument will come later.
29
For further discussion of this point, see Gould (1987, p. 167–178).
30
Also, his work was influenced by Agassiz’s glacier theory.
31
About geological evolution of the Earth, see, for example, Dott and Batten
(1976) and Ozima (1987).
32
Actually, it is an ancient debate between catastrophism and uniformitarianism.
About this debate, see, for example, Cannon (1960), Hallam (1989), and Wilson
(1967). For further discussion about development of catastrophism, see Ager
(1993), Albritton (1989), Gretener (1984), Hooykaas (1970), Palmer (1993),
Rudwick (1997), and Benson (1984).
Thermodynamics time arrow and the logical function of the uniformity principle in geohistorical explanation 23
8. the empirical data showed beyond doubt that the internal energy
of Earth was reduced over time and that the geological phenom-
ena—causes, processes, and effects—are not identical over deep
geological time.33
The two central remaining elements of the uniformity prin-
ciple are uniformity of law and uniformity of process. The mod-
ern theory of actualism, governing the day-to-day work of the
geologist, is based on these elements. One can, therefore, say
that in order to employ the geological-evolutionary worldview
(evolutionism) current among modern geologists, modern geol-
ogy uses the uniformity principle as a methodological principle
encompassing two major elements—uniformity of law and uni-
formity of process. Although these elements are actually a priori
assumptions (metaphysical in a sense), and cannot be subjected
to empirical or logical proof, they enable geologists to realize
their realistic belief concerning the past of Earth, in an artificial
way. In this sense, these assumptions make a geohistorical expla-
nation possible by means of logical-causal arguments—retroduc-
tive and abductive inferences.34
THE ROLE OF THE UNIFORMITY PRINCIPLE IN
THE GEOHISTORICAL EXPLANATION
The Uniformity Principle as a Principle of Simplicity
The practice of geology as a historical science is character-
ized by three major attributes:
1. Geology as a historical science deals with specific (unique)
events in a certain time and place and usually does not con-
cern itself with universal laws, but it accepts them as given.35
2. Geology as a historical science deals mainly with past
events.
3. Geology as a natural science deals mainly with active causes
(efficient causes) and not with functional causes (final
causes).
Items 1 and 2 distinguish geology from the other natural
sciences, such as physics and chemistry, and categorize it as a
historical science similar to conventional history.36
On the other
hand, item 3 distinguishes geology from conventional histori-
cal sciences and places it in the realm of natural sciences.37
The
uniformity principle connects between these attributes, or rather,
artificially unites unique events within a context of causal laws,
characterized by active causes, making it possible to reconstruct
the geological past of Earth. We may, therefore, conclude that
the characterization we are dealing with is a methodological
simplicity principle38
of a certain kind that geologists are obliged
to assume because the past is inaccessible to them.39
They are
obliged to make use of this principle because of their inabil-
ity to examine all geological events that happened in the past
and will happen in the future and must, therefore, content them-
selves with a partial examination of the present, which serves
as a foundation for universal generalizations about events that
are not observed directly.40
By applying the uniformity principle
(serving as the principle of simplicity), geologists can predict
the future and reconstruct the geological past. On the basis of
single geological observations in the present, they construct a
33
Actually, the component of uniformity of state is strongly connected to the
component of uniformity of rate, and therefore refuting the uniformity of state
also means refuting the uniformity of rate, in a certain sense. For empirical evi-
dence on refuting uniformity of state and uniformity of rate, see, for instance,
Austin (1979, p. 39–40) and Gould (1965, p. 226).
34
The uniformity principle is an accepted principle in science and is not con-
fined to geology. In most scientific disciplines, its function is to enable pre-
dictions. In geology, as we will see herein, its main function is to enable the
reconstruction of the geological past, and, therefore, in this paper, I will deal
mainly with abductive inferences—enabling geologists to make inductions of
the past (retrodiction)—and not with deduction. (Here, it should be noted that
in this chapter, contrary to the view as presented and expressed by Peirce and
others, the term “abductive inferences” is introduced in a simplest manner as a
kind of inductive inference. In order to simplify, I define here as “inductive”
all inferences that are not “deductive.”) However, we should bear in mind that
all types of inferences are used in geology (such as induction, deduction, ab-
duction), as in other natural sciences. In this context, see Engelhardt and Zim-
mermann (1988, p. 230, 233, 80–82) and Baker (2013). Generally speaking,
geologists as scientists are particularly interested in researching causes, effects,
and geological laws. Causes and laws allow them to predict effects (deduction).
Joining causes and effects allows them to predict laws and generalizations (in-
duction) and the knowledge of effects and laws enables them to formulate hy-
potheses concerning causes (abduction). This last kind of inference (abduction)
is unique for geology, making it, in a certain sense, a unique science.
35
Certain scientists argue that there is no difference between generalizations
based on singular events and universal laws, and, therefore, there is no substan-
tial difference between a science such as physics and a historical science like
geology. Limitations of space prevent me from addressing this argument in this
paper. In this context, see Şengör (2001, p. 7).
36
About differences between historical science and experimental science, see
Cleland (2001, 2002) and Dodick et al. (2009).
37
This difference results from the fact that conventional history is concerned
mainly with historical processes focused on humans. The engagement with hu-
mans, by its very nature, requires it to focus on functional causes (final causes)
and other human processes (such as sociological, anthropological, economic,
psychological, geographical, etc., processes). Geology, in contrast, deals with
natural processes based on the laws of physics and chemistry, and therefore, as
a rule, does not deal with functional causes but with active natural causes. Geo-
logical reconstruction is not possible thanks to psychology and sociology, but
thanks to the physics, chemistry, and physiology of the world of life (Hooykaas,
1959, p. 149).
38
Defining or describing the simplicity principle accurately is a difficult task,
and still there are many philosophers who engage in it. It is not my intention
to deal with it in detail in the present paper, but only to provide a general ex-
planation in order to understand its connection with the uniformity principle.
What I am interested in is to understand the methodological function that this
principle performs in geological explanation without starting a discussion on
its definition or structure. It is not necessary to understand the simplicity prin-
ciple thoroughly and to know whether it really reflects the simplicity of nature,
but rather to understand its role in geological explanation. For more detailed
understanding of the simplicity principle and its use in science and geology, see
Sober (1975, 1988), Anderson (1963), Goodman (1967, 1964), Baker (2010),
and Zellner et al. (2001).
39
In this context see, for instance, Simpson (1975, p. 275–276), Shea (1982,
p. 458), and Peters (1996, p. 70). Historically, the first to connect uniformi-
tarianism to the simplicity principle was the philosopher Francis Hutcheson
(1694–1746) (Şengör, 2001, p. 38). In addition, Lyell too regarded uniformitari-
anism as a kind of simplicity principle for the purpose of geological research on
the past of Earth. Some claim that what began as a methodological assumption
by Lyell gradually became a geohistorical theory of Earth (Dott, 1998, p. 16).
40
From here, it is clear that the simplicity principle is related to the induction
and curve-fitting problems. For further discussion of these problems, see, for
example, Sober (1988, p. 45–46) and Baker (2010, p. 21).
24 G. Kravitz
9. kind of timeless function enabling them to predict the future and
reconstruct the past.41
This function is continuous and connects
the single observations, and in this sense constitutes a simplifica-
tion enabling geologists to predict the geological state between
observations, before and after them, i.e., it bridges between ob-
servations and theoretical hypotheses concerning the geological
state of Earth at different times (Sober, 1988, p. 45), or, on the
basis of single observations and the uniformity principle, geolo-
gists interpret and artificially imagine reality with the help of
analogies,42
extrapolations, abductive and inductive inferences.
We are actually referring to an artificial principle not necessarily
reflecting reality as it is—it does not necessarily describe na-
ture, but rather it describes what we think about nature and what
we think about the methodology we wish to apply in order to
study it (Goodman, 1967, p. 94–95). Although it serves as an
instrument of realism in relation to the past, it is itself a method-
ological-artificial principle based on the antirealistic uniformity
principle, imagining reality and not necessarily presenting it as
it is in reality.43
Usually science is concerned with an effort to simplify theo-
ries in order to describe them simply and elegantly. Indeed, it is
easier to assume that all the factors, processes, and geological
phenomena seen today are similar to those that happened in the
past and are bound to happen in the future. Geologists are look-
ing for theories to explain a large gamut (as large as possible) of
geological phenomena by means of the smallest possible number
of assumptions (Anderson, 1963, p. 177). This goal is attained by
incorporating empirical data into a broad theoretical framework,
which is what geologists are trying to do when they adopt the
uniformity principle.44
They incorporate observations in the pres-
ent in a timeless system, enabling them to make inferences about
the geological past or future of Earth.45
In other words, this prin-
ciple simplifies reality by artificially integrating empirical find-
ings and observations into a larger system of laws (Hooykaas,
1959, p. 163–164).46
Thus, the uniformity principle can be re-
garded as a pragmatic ahistorical abstraction serving as an inter-
pretative tool (hermeneutic to a certain extent)47
used to decipher
historical phenomena.Any kind of understanding that recognizes
relevant connections involves the capacity to make abstractions
(Lorand, 2010, p. 93). Connections between objects and infer-
ences from findings, i.e., between what is given and known and
what is not given and unknown, cannot be made without a certain
degree of abstraction, enabling orderly connections between ob-
jects. Abstraction essentially means paying attention to a certain
collection of attributes of the object (Lorand, 2010, p. 93–97).
The uniformity principle as a historical abstraction (in contrast to
individuality) assumes similarities between objects and ignores
the differences between them. By means of this principle, geolo-
gists abstract the object of its unique attributes and turn it into
something similar, in certain respects, to other objects.48
From the previous discussion, we understand that inductive
thinking is based on the uniformity principle, and that it is com-
mon in all natural sciences. Its contribution is vital, and without
it, as I will show later herein, the modern geological explanation
breaks down. Geology is concerned mainly with the past, and,
therefore, its explanations rely on abductive inferences49
and on
observations carried out in the present. Unless based on the uni-
formity principle, these inferences cannot be made, and the his-
tory of Earth cannot be reconstructed. Although not exclusive to
geology, it has many practical advantages in the context of the
method of actualism. Its greatest advantage lies in the fact that it
establishes the actualist methodology as a basis for observations
of geological phenomena conducted in the present, and it makes
inferences concerning geological phenomena that occurred
in the past. What are the advantages of geological observations
41
Geology, as a historical science, deals with events that occurred in different
periods and, therefore, had to be united within a timeless system of laws, in
order to derive them logically from each other. Without this—geological expla-
nation would be impossible. In this respect, the uniformity principle is actually
an ahistorical principle, supporting historical explanations of events that oc-
curred in the course of the geological history of Earth.
42
Research methodology by analogy is common, not only in geology and his-
torical sciences, but also in the experimental natural sciences. For instance, the
laws of physics are based on an analogy between causes and effects in several
cases. Gravity (the cause) produces the pull (effect) of one body, just as it pro-
duces the same effect on another body in a different place and time. Therefore,
it is possible to make an analogy from one body to another (a specific analogy
in sense and context to gravity). In geology, we are dealing with similar but not
identical phenomena, and therefore the geologist is obliged to choose the at-
tributes he wants to include in the analogy, which could be causes, processes, or
geological effects. Since we are dealing with similar processes and phenomena,
the act of choosing is prone to be very difficult and subject to errors. The dif-
ficulty lies particularly in the fact that there are no clear-cut rules, subject to em-
pirical testing, for the legitimacy of analogies. Some geologists even maintain
that analogy is inappropriate in geology and suggest using homology instead
(Schumm, 1998, p. 19). For lack of space, I will not address this argument and
not go into any more details than those already mentioned with regard to the
analogical research methodology. For additional details, see Hooykaas (1959,
p. 154–162) and Baker (2013).
43
This is my opinion and it does not necessarily reflect the opinion of other geol-
ogists. As stated, most geologists are realists in relation to the past, and, there-
fore, I assume that they believe that their work methods are adjusted to their
ontological conception concerning the true structure of the world. Apparently,
they believe that their methodology reflects the real world and is, therefore, able
to expose the true geological structure of Earth. In other words, they actually
believe that this method cannot be artificial, but must reflect the real world.
44
In this respect, geologists behave just like most scientists, who search for law-
fulness and simplicity in theory. However, some maintain that nature is much
more complex than the abstractions that we make (Baker, 2000, p. 6). Accord-
ing to them, nature is so complex that it cannot be explained by the simplicity
principle. This is also the reason that it cannot be explained solely by physics
but requires theories from a variety of scientific disciplines. See in this context
Cartwright (1999) and Dupré (1993). I agree with this attitude in certain re-
spects and will discuss it later herein.
45
In a certain sense, this principle provides methodological justification for the
use of inductive and abductive inferences. Naturally, this justification is not
meant to be a logical justification of the induction process.
46
A similar argument can be seen in Goodman (1967, p. 96–97).
47
About natural science as hermeneutic of instrumentation, see Heelan (1983).
48
This artificial procedure eliminates the individuality of the object and thus,
apparently, enables connection between objects. In other words, this abstrac-
tion enables a verbal explanation connecting the individual case to a general
principle, a pattern or a theory. It affords significance to the singular case at the
expense of relinquishing its individuality.
49
As mentioned in footnote 34, the abductive inference is a particular type of
inductive thinking, enabling geologists to make inductions of the past—infer-
ence from knowledge of effects and laws to the hypotheses concerning causes.
The logical structure of this inference will be displayed later herein.
Thermodynamics time arrow and the logical function of the uniformity principle in geohistorical explanation 25
10. in the present? The most obvious advantages are the following
(Frantsuzova and Pavlinov, 1968, p. 9):
1. Geological processes and phenomena in the present are
directly accessible to the geologist. This enables the researcher
to study all the details, taking the dynamics and all the factors
and products into consideration. This enables the geologists to
introduce models and quantitative methods into their research.
2. Processes and phenomena can be continuously studied in
the present and their interrelations identified. This is not always
easy when the sources from the geological past are based on in-
consistent “remnants” and pieces of information concerning geo-
logical processes and phenomena that occurred in the past.
3. The study of geological processes and phenomena in the
present can, to a certain extent, serve as laboratory experiments.
4. Products of processes that occurred in the past should not
be compared to products of processes occurring in the present
only if they happen to be completely identical, but also if cer-
tain differences exist between them. This enables the geologist to
learn about specific geological conditions existing at the time in
the past in which the processes or phenomena occurred.
In spite of these advantages, actualism (based on the unifor-
mity principle) should not be regarded as a universal method pro-
viding complete knowledge about the geological past of Earth.
Actualism is based on inductive (abductive) and analogic infer-
ences enabling geologists to make extrapolations concerning the
geological past and future of Earth. Assuming that the geological
state is changing constantly (a progressive process), we can say
that the longer the time that has elapsed between the geological
phenomenon in the present and the one that occurred in the past,
the less is the chance of similarity between them. When compar-
ing relatively young periods of time, we assume that similarity
between the geological phenomena exists from the point of view
of their causes, processes, and effects, whereas in comparing an-
cient periods with the present, similarity is usually retained only
in the mechanism, or, under the most favorable circumstances,
between causes as well. In other words, reliability of inductive
inferences is reduced for longer elapsed time periods. In some
radical cases, it is impossible to make any inductive inferences
from geological events in the present about those that occurred in
the past (Şengör, 2001, p. 5).
Another problem lies in the fact that the present is only a
small window to the past and does not provide geologists with
a full set of analogies (Frodeman, 1995, p. 965). This is true in
two respects:
1. Sometimes geological events that occurred in the past are
not seen in the present. This may result from the rarity of these
events (perhaps even uniqueness) and from the fact that we have
not had the opportunity to see them again, or that they still occur
today but are hidden from us.
2. The geological processes that form the face of Earth are
usually very slow and take a long time. Sometimes the “life span”
of these periods exceeds that of humans. Therefore, in these
cases, it is difficult to identify the geological effects (outcomes)
and make inferences about their causes.
It should also be mentioned that the uniformity principle is
manifest in qualitative similarity (not in identity) of a rudimen-
tary and general nature. Since geologists do not have direct ac-
cess, they must content themselves with a partial and imprecise
reconstruction, based on similarity between events in the present
and events in the past by means of abstractions and analogic in-
ferences. Unless geologists consider the possibility that similar
outcomes could result from different causes,50
analogic inferences
could lead to mistaken conclusions,51
for instance, geological re-
search of processes occurring in the present in deserts, teaches us
that in hot and dry environmental conditions, there is no vegeta-
tion. However, it is possible that in the remote geological past,
the lack of vegetation resulted from the different chemical com-
position of the atmosphere and not necessarily from hot and dry
environmental conditions.
Geologists should, therefore, be aware of the limitations of
the uniformity principle and the actualist method, and make use
of alternative geological methods according to their needs. In
this situation, some modern philosophers who support actualism
suggest that geological research should be conducted, on prin-
ciple, according to the following four phases (Frantsuzova and
Pavlinov, 1968, p. 11):52
1. They should look for signs (evidence) of geological phe-
nomena from the past. They should study such signs and evi-
dence and describe them from the morphological aspect, their
chemical composition, and stratigraphic structures.
2. The evidence mentioned in item 1 requires a primary
theoretical explanation supported by models based on up-to-date
geological theories.
3. The actualist method (the uniformity and simplicity prin-
ciple) should be used for comparing causes, processes, and ef-
fects in the present, and causes, processes, and effects in the past.
4. On the basis of comparison in items 1 and 3, reconstruc-
tion of the past should be conducted on the basis of similar causes,
processes, and outcomes observed in the present. In this stage,
the geologist actually improves his/her primary explanation (as
he/she did in item 2) on the basis of an empirical comparison car-
ried out in item 3 (by means of the actualist method).
The Uniformity Principle and the Second Law
of Thermodynamics
As mentioned already, modern geologists have adopted, on
the one hand, the geological worldview of evolutionism. On the
other hand, they use the actualist method based on the uniformity
principle, consisting of two main elements, uniformity of process
and uniformity of law. Uniformity of law refers mainly to the
50
Further discussion about the connection between causality and uniformity
principle will come later.
51
With regard to errors in the process of geological interpretation, see Schumm
(1998).
52
In principle, I also support this method, and therefore the description of the
stages includes my interpretations and amplifications that I consider to be rel-
evant for contemporary research methodology. For more in-depth discussion
regarding this issue, see Engelhardt and Zimmermann (1988, p. 233–331).
26 G. Kravitz
11. basic laws of physics and chemistry, while uniformity of process
refers to various geological processes.53
Which law of physics can explain developmental geological
phenomena on a macroscopic level? Actually, there is only one
such law, the second law of thermodynamics.54
Naturally, in geol-
ogy, various physical laws are assumed and applied, but there is
only one historical law that defines geology as a historical sci-
ence. Geologists rely on this law and use it consciously or uncon-
sciously in all their geohistorical explanations. In other words, if
geology, as a historical science, assumes the uniformity of law, it
must rely, among others, on the second law of thermodynamics,
the only one that enables a historical explanation. Since geology
deals mostly with the past (Kitts, 1978, p. 218), reliance on the
second law of thermodynamics is an essential condition for any
geohistorical thinking.55
As already mentioned, the first scientist who explicitly
used the second law of thermodynamics to explain geological
phenomena and to renounce the uniformitarianism of Lyell and
Hutton, was Kelvin, who applied it in his theory of the reduc-
tion of the temperature of Earth and its loss of energy (Hubbert,
1967, p. 25). In contrast to Lyell and Hutton, Kelvin maintained
that Earth was a developing system that loses energy and, there-
fore, cools over time. He rejected the theories of Lyell and Hut-
ton concerning the uniformity of rate and the uniformity of state,
because they conflict with the second law of thermodynamics
(Dott, 1998, p. 17).56
In this sense, Kelvin assumed the thermo-
dynamic, one-directional and irreversible time arrow, and laid the
foundations for the geological developmental orientation that is
accepted by most geologists until today.57
Most modern geologists assume, like Kelvin, that the uni-
formity principle applies according to the second law of thermo-
dynamics, which, by its very nature, promises the rejection of
the uniformity of rate and the uniformity of state. Moreover, this
uniformity principle based on the second law of thermodynam-
ics, by encompassing the uniformity of law and the uniformity of
process, is not just an inductive principle (the principle of sim-
plicity) but a geohistorical principle without which geology can-
not exist as a historical science.
What distinguishes the second law of thermodynamics and
why is it so important for the geohistorical explanation? Most
basic theories in physics do not distinguish between past and fu-
ture, i.e., they are symmetrical with regard to time—they have
no clear preferred direction of the time flow. The equations rep-
resenting these laws are symmetrical in relation to the reversal
of the direction of time. As for the description of the physical
process, the reversal of the sign of the variable time in these equa-
tions makes no difference; for instance, we can sense this process
if we make a film photograph of the process of elastic clashing
between two billiard balls in a table lacking friction, and then run
the film from the end to the beginning. We will not notice the dif-
ferences between the real state of clash and that appearing in the
reversed film, nor will we be able to define the “correct” direction
of the movement of the billiard balls.
In contrast to the other laws of physics, the second law of
thermodynamics describes the macroscopic world of nature as a
world governed by an asymmetric and irreversible time arrow—
in other words, it describes a series of unique events, joined to
each other and developing in one direction (law of historical
succession). Therefore, the majority of physical phenomena, ir-
reversible in the time dimension, are explained by this law. In sta-
tistical mechanics, the second law of thermodynamics is a law of
probability based on a basic concept in physics, that of entropy.
Entropy is a measure of disorder in physical systems. The second
law of thermodynamics states that in closed isolated physical sys-
tems, entropy can be maintained or can even grow in the course
of time up to a point of thermodynamic equilibrium, which is the
most probable final state from a statistical point of view (as an as-
pect of microscopic dispersion of states) in which the system can
exist (a state of maximal entropy and disorder). The law enables
the inference that every closed and isolated physical system has a
time arrow with a clear direction, from a state of low entropy (in
the past) to a state of thermodynamic equilibrium (in the future),
in which the system receives the highest value that it can sustain.
To state it differently, any isolated system is bound to de-
velop over time—from past to future—from a state of low en-
tropy (a certain degree of order) to a state of greater entropy
(disorder in relation to the primary state of the system). This is
the reason that it is impossible to avoid making use of the sec-
ond law of thermodynamics in geohistorical explanation, since it
is the only historical law in physics. Therefore, if geologists are
anxious to rely on physical laws58
and provide geohistorical ex-
planations as well, they cannot refrain from accepting the second
53
We should bear in mind that the uniformity of law is a generic principle rel-
evant for all the natural sciences and not exclusively for geology. Uniformity
of process, on the other hand, is a unique principle for geology. In the past,
geologists distinguished between these variables, by calling the laws of nature
“primary causes” and the geological processes “secondary causes.” They as-
sumed that the secondary causes derive, in certain respects, from the primary
causes. In this context, see, for instance, Simpson (1975).
54
It should be noted that the application of the second law of thermodynam-
ics advocated in this chapter is not affected by the strict limitation to closed
systems. This means that even if we assume that Earth is an open system, it is
still subject to the second law of thermodynamics. (Actually, as a part of the
entire universe, it cannot be really an open system.)
55
It is generally assumed that a good historical narrative contains two kinds of
connections: a causal connection between events described in the narrative, and
the connection of a part to the whole, uniting all the singular events into one
complete narrative (Hull, 1975, p. 260). In this respect, a historical narrative
based on the uniformity principle and on the second law of thermodynamics
meets the criteria of a good historical narrative.
56
Although Kelvin erred in his calculations concerning the age of Earth, he was
the first to assume the evolution of Earth on the basis of the second law of ther-
modynamics. He did not err in that he based his theory on the laws of thermo-
dynamics, but rather because in his days, the phenomenon of the decomposition
of radioactive material (radioactive decay) inside Earth was not known. With
regard to Kelvin’s calculation of the age of Earth, see Burchfield (1975, 1998).
57
In his calculations of the age of Earth, Kelvin wanted to reevaluate Darwin’s
theory of evolution, and particularly of the dominance of physics over geology.
He calculated the age of Earth on the basis of the second law of thermodynam-
ics and thus cast doubt on Darwin’s simplistic and inaccurate calculation in the
Weald valley (Dodick and Orion, 2003, p. 198–199).
58
Apparently they are interested; otherwise, they would not have assumed the
uniformity of law as a basic assumption.
Thermodynamics time arrow and the logical function of the uniformity principle in geohistorical explanation 27
12. law of thermodynamics as a basic assumption.59
This enables
them to distinguish between geological events that occurred in
the past and those occurring in the present, and to join them in a
framework of cause and effect, the cause always being situated
in the past, and the effect always being situated in the present,
and not the other way round.60
As we have seen, this is the most
basic assumption on which the geologist bases his belief in real-
ism in relation to the past. This means that the second law of
thermodynamics and Ludwig Boltzmann (1844–1906)’s “past
hypothesis” (from which the thermodynamic time arrow derives)
play a central role in geohistorical explanation, without which the
modern explanation would break down.61
Their role is especially
evident in the context of the uniformity principle, an ahistorical
principle that enables a historical explanation of events that oc-
curred in the course of the geohistory of Earth. On the face of
it, there is a contradiction here (how is it possible that the same
principle is ahistorical, on the one hand, and contains a historical
law, on the other?), but in reality, such an explanation is possible
by assuming the second law of thermodynamics—a physical law,
ahistorical in nature—and the thermodynamic time arrow, which
makes it historical in this sense.
Nevertheless, it should be mentioned that the second law of
thermodynamics is not without difficulties and disagreements.
On the macroscopic level, the law explains the irreversible phe-
nomena and the asymmetry of the time arrow, as perceived in-
tuitively by us, but this is not the picture obtained if we want to
explain macroscopic events based on physical laws on the micro-
scopic level.
As already mentioned, most of the theories in physics do not
distinguish between past and present or, rather, are symmetrical
with regard to the reversal of the direction of time. Equations rep-
resenting these laws are symmetrical with regard to the descrip-
tion of the physical process; the reversal of the sign of the time
variable in these equations makes no difference, and, therefore, if
you assume that the world is composed of microscopic particles
(atoms), the reduction of the second law of thermodynamics to
Newton’s mechanic laws is impossible. For example, if we fol-
low the reaction of gas on the microscopic level, we will find
that the motion of the gas molecules is governed by Newton’s
laws and equations of motion, which are symmetrical with re-
gard to the direction of time. If we place t+ and t– in these equa-
tions, we will obtain identical descriptions of the process from
the physical point of view in both cases. On the other hand, if we
examine the same gas on the macroscopic level, we will notice
that the gas reacts according to the second law of thermodynam-
ics—the gas spontaneously aspires to achieve a state of thermo-
dynamic equilibrium. In other words, when we examine the gas
on the macroscopic level, we identify an asymmetrical and ir-
reversible direction of time, and when we do so on the micro-
scopic level, the process is neutral (symmetrical) with regard to
the direction of time. Therefore, the main difficulty lies in the
fact that the second law of thermodynamics is irreversible and
asymmetrical with regard to the direction of time and cannot be
derived fully from the laws of motion of Newton’s mechanics (or
from the laws of motion of quantum mechanics), which are sym-
metric and reversible in time.62
If the world of atoms described by Newton’s laws of mo-
tion is symmetrical and reversible in the aspect of the time arrow,
then it is difficult to explain why, in our daily observations, we
encounter processes occurring in one direction (i.e., governed by
the second law of thermodynamics). Physicists and philosophers
attempted to solve this difficulty in the nineteenth century, and the
subject is still open to discussion and disputes. The outstanding
physicists who have tackled these problems are Boltzmann and
James Clerk Maxwell (1831–1879). Both of them reached the
conclusion that the second law of thermodynamics is a statistical
law, very plausible, but not mandatory, i.e., under certain excep-
tional conditions, it can be renounced without its universality
suffering severe harm. In order to explain the irreversibility of
the time arrow in reality, Boltzmann argued that natural phe-
nomena are not explained solely by laws but also by initial con-
ditions. Such states can occur in initial conditions of phenomena
occurring in the direction of time, as observed today, but also
in initial conditions in the opposite direction of time, which is
possible but has never been observed in reality. Thus, Boltzmann
attempted to solve the problem of reduction between Newton’s
laws of mechanics and the second law of thermodynamics by
59
Actually the second law of thermodynamics is well adapted to common sense
and to the physical world in which we live our everyday lives (on the macro-
scopic level). The assumption of an asymmetrical and one-directional time
arrow is an intuitive assumption. In everyday macroscopic processes, we iden-
tify a one-directional flow of physical processes in time. We are present in our
ageing process and always remember the past and never the future. Even simple
processes like that of ice cubes melting into water are subject to the second law
of thermodynamics. Ice always melts in water, and we have never seen an op-
posite process, in which ice is produced in a glass of warm water. Heat always
flows from a hot to a cold body until their temperature reaches an equilibrium
(the stage of thermodynamic equilibrium). This flow is a spontaneous process,
and we have never witnessed an opposite process of the flow of heat from a cold
body to a hot body. All these are spontaneous processes testifying to a clear and
irreversible direction of the time arrow. Nevertheless, geology as a scientific
discipline cannot rely only on human intuitions and must obtain support for its
assumptions from other scientific disciplines, i.e., as a discipline belonging to
the natural sciences, it must also explain the assumption concerning the one-
directional nature and irreversibility of the time arrow by means of the laws of
physics; otherwise, the geohistorical explanation will be scientifically incom-
plete. As already mentioned, the most appropriate physical law for a geohistori-
cal explanation is the second law of thermodynamics, which is a law of physics
on the one hand and a kind of historical law on the other.
60
As mentioned, the second law of thermodynamics describes a system develop-
ing in time from a state of low entropy (in the past) to a state of thermodynamic
equilibrium (in the future), in which the state of entropy of the system reaches
the highest value it is capable of. These thermodynamic states change in a con-
tinuum, and, therefore, we can speak only of similar states and certainly not of
identical states. Besides, one state is causally affected by another, and this is
the basis of the causal arrow, which I will discuss in the following. The thermo-
dynamic and causal arrows enable us to discover the geological causes in the
past on the basis of the effects observed by geologists in the present.
61
I will discuss later herein the special status of the second law of thermodynam-
ics and Boltzmann’s past hypothesis in the geohistorical explanation.
62
In other words, there is a fundamental difficulty in reducing the second law
of thermodynamics, which is irreversible and asymmetrical in the aspect of
the direction of time, to the laws of motion in Newton’s mechanics, which are
symmetrical and reversible in time. For a detailed discussion, see Sklar (1993),
Price (1996), Callender (2001), and Albert (2000).
28 G. Kravitz
13. assumptions about the initial conditions of the system and not
necessarily about the laws themselves. In his opinion, initial con-
ditions are usually asymmetrical and irreversible from the time
perspective. The rare state that appears to refute the second law
of thermodynamics, Boltzmann explained by means of his defini-
tion of entropy. He claimed to have succeeded in proving that any
macroscopic state can be described by means of a large number
of microscopic states equaling it. Boltzmann defined entropy as
a physical size measuring several existing possible microscopic
states for the purpose of describing a certain macroscopic state.
He showed that the macroscopic state with the highest degree
of entropy (thermodynamic equilibrium) is identical to the state
describing the greatest number of possible arranged microscopic
states. Moreover, a state of thermodynamic equilibrium is the
most probable state in which a system will exist, and it, therefore,
spontaneously aspires to achieve it. This is the reason that we
observe the asymmetrical and irreversible processes that occur
according to the second law of thermodynamics.
The problem is that the statistical mechanics of Boltzmann,
as presented here, are based on Newton’s laws of mechanics,
which are symmetrical with regard to time direction. Therefore,
one may argue that, as Boltzmann considered that entropy could
grow in the direction of the future, it could also grow the other
way round—in the direction of the past. Everybody can agree
that entropy is bound to grow, but why should we assume that
it grows only toward the future, and not toward the past? If the
increase in entropy does not have a clearly defined direction from
the past toward the future, it might just as well flow from the fu-
ture to the past. In this way, one could argue that, as energy flows
from a warm body to a cold body, it could just as well flow from
a cold body to a warm body.
This embarrassing problem was raised by the physicist
Joseph Loschmidt (1821–1895). Boltzmann suggested a solution
to Loschmidt’s problem by posing his famous “past hypothesis,”
thereby providing an answer to the question why entropy grows
in the direction of the future, or rather, why we witness asymmet-
rical and one-directional physical processes of the time arrow. By
means of this hypothesis, Boltzmann placed the responsibility for
asymmetry of the time, as observed nowadays, on the initial con-
dition of the universe. At the starting point, the universe was in
a state of low entropy, which grew continuously in the direction
identified by us at present. This hypothesis enables us to maintain
the symmetry of Newton’s laws of motion on the microscopic
level while also explaining why, in spite of this symmetry, we
observe asymmetrical and irreversible thermodynamic processes
from the point of view of the direction of time. Nevertheless, it
should be remembered that Boltzmann’s “past hypothesis” is no
more than a hypothesis. Boltzmann never managed to prove it,
and it remains a metaphysical assumption to this very day. The
controversy concerning this hypothesis has not ceased, and many
physical and philosophic questions still remain unsolved. Most
of them are concerned with the initial state of the universe. Why
was it in a state of disequilibrium? If the state of low entropy is so
unreasonable, why should the universe be in such a state? These
questions and many others are still discussed by physicists and
philosophers, and I do not intend to deal with them or to resolve
the subject of the time arrow in this paper but only to emphasize
that the problem of reduction between the second law of thermo-
dynamics and Newton’s laws of motion is still not solved.63
This state of affairs has implications for geology as a sci-
ence dealing with the past in general, and with realism in re-
lation to the geological past in particular. Realism in relation
to the geological past of Earth is based on the assumption of
the one-directional and irreversible thermodynamic time arrow.
This is based on Boltzmann’s past hypothesis, which cannot be
derived from the motion equations of mechanics, as these are
invariant with regard to the reversal of the direction of time. In
a certain sense, this important fact exposes the metaphysical
nature of geology as a historical science, and its methodologi-
cal principle—the uniformity principle. In the last resort, as I
showed previously herein, this principle is based on the second
law of thermodynamics, which determines the direction of the
time arrow on the basis of Boltzmann’s metaphysical hypothesis
concerning the initial state of the universe. Until the problem
of Boltzmann’s “past hypothesis” is solved, the geohistorical
explanations will not be conclusive; however, it should be men-
tioned that this reservation does not destroy the legitimacy of
geology as a science. Physics serves as a scientific support for
geology, and, therefore, the fate of geology will be the same as
that of physics.
The Uniformity Principle, Causality, and
Geohistorical Inferences
As we have seen, the uniformity principle is, in a certain
sense, a principle of simplicity, the main function of which is
to serve as a logical-methodological “tool” for coping with the
time arrows and the historical-evolutionary view of the world.
To be more specific, its main role and goal are to enable geolo-
gists to provide geohistorical explanations by means of logical-
causal explanations (such as: retrodiction, abduction) in order
to overcome the difficulty inherent in relying on a geological-
evolutionary worldview, based on the assumption of the second
law of thermodynamics, or the thermodynamic time arrow. In
practice, this principle makes it possible to bridge between em-
pirical observations in the present and theoretical hypotheses
concerning the past and future of Earth, and this is its function.
It is made possible by means of logical-causal arguments used
by geologists to explain geological phenomena. The structure
of these arguments resembles Hempel’s famous model—the
covering-law model.64
As in Hempel’s model, these arguments
contain an explanans part and an explanandum part. The ex-
planandum part is the conclusion of the argument and describes
events that occurred in the past. The explanans part contains two
63
For more in-depth discussion regarding time arrow and Boltzmann’s past hy-
pothesis, see Albert (2000, p. 1–21, 71–96).
64
About the covering-law model and its role in historical explanation, see
Weinryb (1987, p. 77–121) and Kitts (1977, p. 6–12).
Thermodynamics time arrow and the logical function of the uniformity principle in geohistorical explanation 29
14. kinds of introductions—those describing events in the present
(initial conditions) and those concerned with timeless universal
generalizations. Timeless universal generalizations are based on
the uniformity principle, and without them, no arguments con-
cerning the past are possible.65
They provide a kind of logical
coverage to the introductions describing events in the present
and enabling them to make logical inferences concerning events
that occurred in the past. As in physics and other natural sci-
ences, bridges by means of general laws and generalizations
contribute to the understanding of the geological explanation.
The explanation of specific events in accordance with a general
law or generalization places it as part of a larger general system
behaving in accordance to a known system of laws. This system
of laws provides the general system with the order and cohesive-
ness that make them understandable. When an event occurs ac-
cording to a certain law, it is not extraordinary but expected and
understood as a detail in a larger system.
Geologists show that a geological event was bound to occur,
not only on account of their familiarity with the specific facts,
but also as a result of their knowledge of general laws that can
be put to test in other cases and in other times as well. Such ex-
planations are used in all natural sciences and not just in geology.
The special contribution of the uniformity principle to the geo-
historical explanation based on abductive inference (abduction)
is unique for geology. Peirce claimed that explanations in the
earth sciences differ substantively from explanations in other ex-
perimental sciences, such as physics and chemistry. Peirce, like
Whewell, attacked Lyell’s induction.66
In contrast to this induc-
tion based on a search for findings (facts) that could support his a
priori conceived theory, Peirce suggested a thinking process that
used data (facts) in order to create a theory. He called this process
“retroduction” and based it on abductive inference, from a his-
torical outcome, of the causes and states that caused this outcome
to occur (Dott, 1998, p. 16).67
Usually, in the empirical natural
sciences, explanations are based on logical inferences of the de-
duction/induction type. In contrast, the earth sciences naturally
deal with the history of Earth, and therefore most of their expla-
nations are based on an inference of the abduction type, inferring
the causes that occurred in the past from the outcomes (geologi-
cal effects) in the present (Engelhardt and Zimmermann, 1988,
p. 82, 210).68
The uniformity principle plays a decisive logical role in
inferences of the abductive type, allowing geologists to apply
realism in relation to the past. In order to understand how the
uniformity principle integrates in the abductive inference, and its
logical role, one must first understand its logical structure. This
logical structure is usually defined as follows:
If H, then I
I ________
H
where H represents the geological causes that occurred in the
past, and I represents the geological results observed in
the present.69
It is obvious that the argument is not logically
valid, and therefore result I cannot be assumed to be caused
with certainty by the cause H. One of the greatest difficulties
in retrodiction70
in geology derives from the fact that the same
outcome can result from different causes (Kitts, 1978, p. 222).71
Finding the exact cause (as far as possible) in the remote past
requires massive interpretative work, and even then we are not
sure to find the true cause of the outcome (that we observe in
the present).72
In order to overcome the problem and increase
the validity of the argument presented here, geologists assume
65
About this point, see Kitts (1977, p. 5).
66
For further discussion of Lyell’s geological principles, see Lyell (1830, 1832,
1833) and Rudwick (1998).
67
Of course, this explanation of Peirce’s logic is too simplistic, but it meets the
requirements of this paper. Peirce considered logic to be an ideal for productive
inquiry. According to Peirce, abduction is not concerned with results caused
with certainty by the causes; abduction is concerned with a continuing process
of fruitful inquiry, not with an explanation that can be immediately justified
with certainty. For further discussion of Peirce’s logic and abduction inference,
see Fann (1970), Josephson and Josephson (1994), Magnani (2001), Flach and
Kakas (2000), Kruijff (1998), Bird (1959), and Burch (2009).
68
This argument is valid for all historical sciences and not only for geology.
About this point, see Simpson (1963, p. 45).
69
There is a substantial difference between logical derivation and causal deriva-
tion. In contrast to logical arguments, causal arguments are concerned with facts
pertaining to the state of affairs in the world, and their examination requires an
examination of things in the world. In our case, we engage in logical arguments,
but these contain causal (factual) arguments concerning the geological state of
Earth in the present and the past. Geologists use logical arguments on the one
hand, whereas on the other, their explanations are causal explanations based on
factual arguments.
70
For further discussion about retrodiction process, see Engelhardt and Zim-
mermann (1988, p. 212–218) and Kitts (1977, p. 39–47).
71
In this respect, an asymmetry exists between the process of prediction and the
process of retrodiction. The difficulty in making predictions is that the same
cause can have several different effects. On the other hand, the difficulty in
retrodiction is that the same effect can have many causes.
72
Sometimes the work of the geologist is likened to the work of a detective
(Frodeman, 2000, p. viii; Baker, 2000, p. 7) or a physician. The detective ar-
rives at the scene of the crime and finds the effect (the body of the victim, a
house broken into, etc.). On the basis of signs in the area and evidence, the
detective attempts to construct the event and find the cause of the crime. Simi-
larly, the physician searches for the illness in the symptoms manifesting in the
patient. The geologist, like the detective and the physician, looks for the causes
of geological events and phenomena. As a matter of fact, such a type of re-
search first offers a variety of possible hypotheses (the possible causes for the
appearance of a certain effect) that explain the effect, out of which the geolo-
gist tries to find the inference to the best explanation or, in other words, to the
one that is most confirmed (since one effect can have many causes, there might
be several hypotheses that explain the same effect). The hypothesis chosen is
sometimes called the ruling hypothesis, as it offers the best explanation for a
certain phenomenon. Such a hypothesis can be chosen by eliminative induc-
tion—the less promising hypotheses are discarded, and the best is retained—or
by the combination method (in light of the complexity of geological processes,
sometimes several hypotheses are required to explain a certain phenomenon).
This hypothesis guides the geologist in his daily work up to the stage when he
obtains data that refute it. As soon as the hypothesis is refuted, the geologist
begins to look for another hypothesis (using the same method). This process
is extremely complex and sometimes termed “the method of multiple working
hypotheses.” (See the development of the process in Chamberlin [1897] and
Kitts [1977, p. 102–114].) I do not intend to discuss the matter further in this
chapter. What is important to understand is that this complex process is based
on an abductive inference, as described earlier. For further details concerning
the process of choosing, confirming, or refuting hypotheses in geology, see
Schumm (1998, p. 10–34).
30 G. Kravitz
15. the uniformity principle as a kind of “covering law.” To be more
specific, the assumption “if H, then I” is a hypothesis of a kind,
and it appears as a law or a causal generalization. This general-
ization does not assure the one-to-one causal relation between
the cause and the effect, and therefore many possible causes for
the same effect are feasible. In order to strengthen the causal
relation, a law or generalization with a stronger connection is
required. Such a generalization is often called biconditional
law,73
and its role in argument is to assure that the cause (H)
will be a sufficient and necessary cause74
for the occurrence of
the effect (I). Only if the cause (H) occurs will the effect (I)
certainly occur.75
As a matter of fact, geologists assume the uni-
formity principle as a cover law, thus attempting to improve
(artificially) the hypothesis “if H, then I,” bringing it to the fol-
lowing form: If H and only H, then I. On account of this as-
sumption, the argument obtains the following improved form:
If H and only H, then I
I _ _______________
H
Here, one can see that the logical-causal connection between H
and I is stronger, and therefore H can be inferred from I with
greater probability. In a certain sense, the abductive inference
is based on an inductive statistical generalization, and therefore
such a generalization is often called “probabilistic postdictive in-
ference” (Kitts, 1977, p. 14–16). Inductive inference is accepted
in science and is based on a thought process by which, on the ba-
sis of singular cases, generalizations, including all such cases, are
made. In this process, on account of the fact that we have found
a large number of objects with the attribute A, we generalize that
all objects of this kind (with no exception) possess the same attri-
bute. By means of a similar process, the generalization “if H, then
I” was made, and when geologists add the uniformity principle to
it, they artificially “improve” the force of the inductive inference,
as a result of which a stronger causal generalization ensues—if H
and only H, then I.76
Thanks to this generalization, the abductive
inference from the present to the past becomes, so to speak, a
valid deductive inference.77
In this sense, the uniformity principle
bypasses the gap between the present and the past (which, as men-
tioned already, is one of the main problems of realism in relation
to the past), enabling the scientist to present causal arguments,
thus expanding the classical principle of causality, which states
“everything necessarily has a cause.” This argument, to which the
uniformity principle is attached, becomes a more focused argu-
ment: “the same causes necessarily have the same effects.” This
argument formed the bases of the improved argument: “If H and
only H, then I.” If so, the uniformity principle expresses the unity
of nature in terms of orderly and uniform natural laws. These
laws can be applied only if we assume that there is a uniform
principle of causality, namely, that the same causes will neces-
sarily produce the same effects. In this sense, when geologists
use causal explanations, they start from the assumption that the
same causes will necessarily produce the same effects, and hence
the realistic belief that when we observe a phenomenon in the
present, we are able to discover its cause78
; i.e., in geohistorical
explanations, causes are sufficient and necessary conditions for
the occurrence of the effects. It is enough that eventA (the cause)
occurs, for event B (the effect) to occur as well. This is the basis
for the possibility of inferring “backwards” (retrodiction).
Why does the uniformity principle require the obligatory
relation between a certain cause and a certain effect? As shown
earlier herein, the uniformity principle is based on the second law
of thermodynamics. In statistical mechanics, this law describes
an evolutionary process progressing from a state of low entropy
to a state of growing entropy. In this process, the geological phe-
nomena and events are singular events in a certain sense, and
every one of them is influenced by the one that preceded it in
time (Engelhardt and Zimmermann, 1988, p. 323), and, there-
fore, it is possible, on principle, to infer from every state, what
73
See, for example, Engelhardt and Zimmermann (1988, p. 208).
74
I will hereby clarify some of the concepts, such as “sufficient condition” and
“obligatory condition.” Sufficient Condition—Event H is a sufficient condition
for the occurrence of event I only, and only if when event H occurs, event I too
occurs, i.e., it is enough that H occurs for I to occur. Obligatory Condition—
Event H is an obligatory condition for the occurrence of event I, only, and only
if without the occurrence of event H, event I cannot occur, i.e., if H does not
occur, I too cannot occur.
75
Namely, the effect I can occur only as a result of cause H, and effect I cannot
be caused by any other cause. In terms of logic, one could say that geologists
exchange a truth function called material implication (material conditional) for
another truth function called logical equality (biconditional).
76
Here, I should mention Lyell, who also based uniformitarianism on inductive
geology and on vera causa. Some geologists claim that Lyell’s uniformitarian-
ism, like that of Playfair and Herschell, is based on inductive inference for
which the validity and justification are based on vera causa. On the other hand
the catastrophism of Whewell and Sedgwick is based on abductive inference
and retrodiction (in this context see Baker, 1998). The abductive inference, as I
regard it, along with the uniformity principle, integrates abductive and inductive
inference into one whole.
77
We are referring to a kind of transformation that enables us to infer geological
events that occurred in the past from arguments concerning geological events
occurring in the present. However, I must stress that although adding the uni-
formity principle to the argument improves the reliability of the inductive infer-
ence, it does not justify the process of induction from a logical point of view. As
for the justification of the process of induction, see Black (1964).
78
We should remember that I made this inference on the basis of the structure of
the improved abductive argument based in the uniformity principle, which, as
mentioned before, is a methodological and artificial principle, in a certain sense.
This is where the central problem of modern actualism is exposed. Apparently,
geologists are not aware of this philosophical conclusion and are confronted
with a multitude of practical problems concerning geological causality. For
example, they often claim that the same cause can have various effects (diver-
gence) or that various causes could produce the same effect (convergence). In
addition, they claim that a certain effect is sometimes caused by a combination
of various causes (multiplicity). With regard to practical problems pertaining
to geological causality, see Schumm (1998, p. 58–75, 95–119). These argu-
ments are correct from a practical point of view but contradict the philosophical
conclusion deriving from the logical integration of abductive inference and the
uniformity principle (assumed by the geologists themselves). From a pragmatic
point of view, their actions in the practice of their profession are perhaps justi-
fied, but this does not cancel the difficulty rising out of the logical-conceptual
analysis of the uniformity principle. As a matter of fact, since geologists cannot
renounce the uniformity principle as a method of work, since its absence would
preclude the geohistorical explanation, they use it by default. At the same time,
they adopt the multiple working hypotheses (as described earlier), in order to
increase the probability of finding the true reasons for the effects that they are
observing.
Thermodynamics time arrow and the logical function of the uniformity principle in geohistorical explanation 31
