Download IS THE PRINCIPLE OF THE UNIFORMITY OF NATURE A

IS THE PRINCIPLE OF THE UNIFORMITY OF NATURE
A SCIENTIFIC HYPOTHESIS?
Ayhan Sol
Introduction
Wesley Salmon (1953) distinguishes three different formulations of the
principle of the uniformity of nature (hereafter UP): first, as an empirical truth, due to
J. S. Mill; secondly, as a truth established a priori, proposed by Kant; thirdly, as a
necessary postulate of science, truth of which cannot be demonstrated, defended by
John Venn and Bertrand Russell.
In this paper, I defend the thesis that UP is metaphysical (the third formulation
above) against the claim that UP is a confirmable or falsifiable general scientific
hypothesis (the first above). The proponents of the claim that UP is a confirmable or
falsifiable scientific hypothesis conceive UP as a scientific hypothesis that is implied
by the laws of nature. I will endeavor to show that the arguments offered to support
these formulations cannot be defended against the idea that UP is metaphysical.
Confirmability of UP
Hans-Jürgen Treder (1971), in a similar spirit with J. S. Mill, makes the
following claim:
Astronomic observations directed beyond the Milky Way Galaxy directly
scan a 104 million-year time slice of the universe. These observations have
proved the truth of natural laws as asserted by the general theory of relativity.
According to Einstein‟s general theory of relativity, the laws of relativistic
quantum theory are true for all space and time. This is the most certain
statement of the actualism principle i.e. UP given so far, and therefore this
principle should be used in cosmogony and geogony without any restriction
(this is true especially for the values of universal constants). … For this
reason, historical geology can start from the fact that natural laws have been
the same in the past as in the present. (p. 204, my translation)
This paragraph suggests that since the laws of physics are confirmed, so is UP.
Treder‟s argument is also supported by Wolfgang Blei (1981).
Relying on Treder‟s argument, Celal _engör (1993) asserts that “the actualism
hypothesis as one of the most fundamental presuppositions of historical sciences is
not metaphysical as having been believed up to the recent times, but rather a
[falsifiable] scientific hypothesis.” (p. 19, my translation)
Such claims require a strict connection between UP and the laws of nature in the
sense that the latter are more fundamental than, thus implies, the former. For instance,
J. P. Day (1975) asserts that “the Principle of Uniformity … is secondary to the
Principle of Determinism [„Nature is regular‟, i.e. there are laws of nature], since the
former presupposes the latter. For unless there are laws of nature, the question
whether they are constant or not cannot arise.” (p. 3) Here UP is defined in terms of
the constancy of laws of nature that can be formulated in the following way: if the
laws of nature are spatio-temporally constant (unchanging) nature is uniform. The
rationale behind the definition of the uniformity in terms only of the constancy of the
laws of nature rather than the constancy of all properties of things is that the latter
would lead to a conception of unchanging universe. (In fact, such a view of UP was
proposed in geology by Charles Lyell, a leading geologist of the nineteenth century
and the founder of the doctrine of uniformitarianism. According to Lyell, all main
geological features of the earth, e.g. mountain ranges, continents, oceans, and even
their extension, quantities, etc., as well as the laws of physics and chemistry have not
changed. Of course, Lyell did not deny change, but he insisted that where any thing
ever changed it changed uniformly.) The former, on the other hand, suggests merely
that space and time irrelevant with regard to the laws of nature. That is, the relations
described by the laws hold irrespective of space and time.
However, instead of using the language of „laws of nature,‟ which is loaded with
its own philosophical problems this claim can also be formulated in terms of general
scientific hypotheses (i.e. scientific laws) in the following way: if there is at least one
general scientific hypothesis which is true for all space and time positions then UP is
true (i.e. nature is uniform). In terms of confirmability, this claim can be restated as
follows: if there is, at least, one general scientific hypothesis which is confirmable for
all space and time positions then UP is also confirmable.
It is evident from the above formulations that UP is conceived as a general
scientific hypothesis truth (or confirmability) of which is determined by the truth (or
confirmability) of general scientific hypotheses, and that UP is secondary relative to
other general scientific hypotheses.
I admit that the truth of general scientific hypotheses would guarantee the truth
of the UP on the following condition: if there is, at least, one true (confirmed) general
scientific hypothesis implying UP then UP is also true (confirmed). However, it can
be objected that since it is impossible to confirm general scientific hypotheses in the
absolute sense it is also impossible to confirm UP. Of course it may still be
maintained that scientific laws cannot also be confirmed in the absolute sense but they
are not considered as metaphysical. Against this argument it may be asserted, in
accordance with the Popperian criterion of demarcation, that although scientific
hypotheses are not confirmable they are falsifiable, thus not metaphysical. Before
investigating as to whether UP is also falsifiable I need to examine a possible
objection that even though general scientific hypotheses cannot be confirmed in the
absolute sense they are, at least, relatively confirmable.
Relative confirmation of UP
As for the relative confirmation of UP, it can be claimed that although we
cannot confirm UP in the absolute sense we can confirm it relative to the available
evidence. That is, as a general scientific hypothesis implying UP is confirmed relative
to the tests and observations up to a certain time it can be claimed that UP is also
relatively confirmed. However, historical examples testify against this claim. For
instance, the classical mechanics had been proposed and relatively confirmed up to a
certain time. Accordingly, it may be claimed that UP had also been confirmed up to
that time. But when the classical mechanics was finally disconfirmed should we say
that UP was also disconfirmed? But the quantum mechanics, that replaced the
classical mechanics and is also implying UP, has also been confirmed relatively to the
available evidence. There appears to be a dilemma: UP, once disconfirmed, is again
confirmed. This confirmation-disconfirmation and revival of UP may go on
indefinitely as new general scientific hypotheses are disconfirmed and confirmed. The
fact that UP always keeps its place in scientific theories suggests that UP is a
metaphysical presupposition of science.
Falsifiability of UP
As for the falsifiability of UP, it may be contended that even if UP is not
confirmable it is, at least, falsifiable. We can formulate this in the following way: if a
general scientific hypothesis implying UP is falsified, i.e. it is not true for all space
and time positions, UP is also falsified, i.e. it is not true for all space and time
positions. However, we cannot claim that if a general scientific hypothesis implying
UP is falsified no other general scientific hypotheses implying UP can be formulated.
So in order to falsify UP we should be able to falsify all possible general scientific
hypotheses implying UP, which is impossible.
However, a proponent of the falsifiability thesis may claim that even though we
cannot falsify all possible general scientific hypotheses implying UP we can still
maintain the claim that since all possible general scientific hypotheses are in principle
falsifiable UP is also in principle falsifiable. However, there is a problem with this
account. For even if all possible general scientific hypotheses are in principle
falsifiable, since we will never falsify all of them we will never give up UP. This is
what is generally meant by a principle being metaphysical. Moreover the-in-principlefalsifiability of UP does not necessarily follow from the-in-principle-falsifiability of
general scientific hypotheses. That is, even if H1 implies H2 it does not follow that H1
and H2 must have exactly the same properties, such as the-in-principle-falsifiability.
Furthermore even if we were ever to give up UP it would not be as a result of
the falsification of general scientific hypotheses. Rather, we would give up UP in the
Kuhnian sense, i.e. as a shift from hypotheses implying UP to hypotheses implying
non-UP. However, I think this would not ever be possible because every hypothesis
must presuppose some kind of uniformity, local or universal. Otherwise science, as
we understand it, would not be possible.
Ayhan Sol
Department of Philosophy. Middle East Technical University, 06531 Ankara, Turkey.
[email protected]
REFERENCES CITED
Blei, W. 1981. Erkenntniswege zur Erd- und Lebensgeschichte. Ein Abrib:
Akademie-Verlag, Berlin.
Day, J. P. 1975. The Uniformity of Nature. American Philosophical Quarterly
12/1, 1-16.
Salmon, W. 1953. The Uniformity of Nature. Philosophy and
Phenomenological Research 14, 39-48.
Sengör, A. M. C. 1993. Tarihsel Disiplinlerin Bilimselligi Üzerine. Bilim Tarihi
No: 25, 11-30.
Treder, H. J. 1971. Thesen zur Kosmogonie und Erdstehung. Berichte der
Deutschen Gesellschaft der Geologischen Wissenschaften-A 16, 201-205.