Michael Ruse (and many others) contend that science is constrained by methodological naturalism, which is the thesis that that neither the data, for a scientific investigation, nor a scientific theory nor the background beliefs, against which a theory is assessed, can properly refer to or contain supernatural beings or propositions based on revelation. In Darwinism Defended Michael Ruse seems to think science, by the very definition of science, is constrained by methodological naturalism. He writes,
Furthermore, even if Scientific Creationism were totally successful in making its case as science, it would not yield a scientific explanation of origins. Rather, at most, it could prove that science shows that there can be no scientific explanation of origins. The Creationists believe that the world started miraculously. But miracles lie outside of science, which by definition deals only with the natural, the repeatable, that which is governed by law.
Ruse’s specific target here are creationists who typically contend that the world was created around 6-10 thousand years ago, in 6×24 hour days and that the fossil record is the result of a world-wide flood. However, the definition he offers excludes far more than this specific position. Ruse’s definition entails that any reference to God’s activity is unacceptable in scientific theorising. Any claims such as that the universe was created (in some way or another), that God created the universe ex nihlo, that God sustains the universe, upholds laws of nature God or even theological interpretations of the big bang and the advocacy of theistic evolution would be ruled out as non scientific.
Moreover, this ruling out is a prori. It is not that scientists have examined whether God exists, that they have gathered evidence showing he does not exist and this has become a settled, peer-reviewed, consensus; science has, in fact, done no such thing. Further, Ruse is clear that his definition would hold even if God does exist and even if there is compelling evidence for his existence. Science would not consider such facts in its theorising; the very rules governing scientific inquiry would rule it out of consideration from the outset. This is because, according to Ruse, science by definition deals only with what is:
Elsewhere in the same article Ruse defines in more detail what he means by (iii). He states,
[A]n approach to the empirical world that demands understanding in terms of unbroken law. That is to say, understanding in terms of regularities, which in some way or an other we feel are more than mere contingencies, but rather part of the necessary succession of the empirical world.[Emphasis added]
Ruse contends that science only postulates and presupposes objects and properties that are natural, repeatable and governed by laws of nature. He understands these as regularities grounded in some form of necessary succession.
Alvin Plantinga argues that Ruse’s definition of science is mistaken,
What about the Big Bang: if it turns out to be unrepeatable, must we conclude that it can’t be studied scientifically? And consider the claim that science, by definition, deals only with that which is governed by law—natural law, one supposes. Some empiricists (in particular, Bas van Fraassen) argue that there aren’t any natural laws (but only regularities): if they are right, would it follow that there is nothing at all for science to study?
Plantinga here suggests that Ruse’s conditions (ii) and (iii) are subject to straightforward counter-examples and that, as such, his definition is mistaken. In Methodological Naturalism Under Fire Ruse responds to both these criticisms. Below I will examine Ruse’s response and argue that it is unsuccessful.
The Repeatability Requirement
Turning to (ii), Plantinga notes that on at least one possible cosmological model the big bang is unrepeatable. Despite this studies into the first instant of the big bang are clearly parts of science and would continue to be so even if this model is true and the big bang is unrepeatable. It follows from this that science can study unrepeatable events which renders (ii) false.
Ruse’s response is two-fold; first Ruse suggests that Plantinga is repeating a common line of argument,
As a matter of fact, Plantinga here is raising an objection which has often been raised by critics of the claim that scientific understanding involves reference to law. His point, as was theirs, is that there are many unique events that science must surely try to cover and under stand, but that given the uniqueness of these events, in some sense this precludes lawful understanding.
Ruse then goes on to address this common line of argument,
But, as many critics of the critics have countered, there surely has to be some thing wrong with this argument. Take for in stance the demise of the dinosaurs at the end of the Cretaceous. This was in it self a unique phenomenon and un repeat able; but, uniqueness not with standing, the demise was made up of many factors which can individually be brought beneath lawful under standing. To day, it seems most probable that an asteroid or a comet or some such thing hit the earth. This was no unique phenomenon, nor was the hit ting of the earth by the asteroid or comet such that the normal laws of nature – that is to say Galileo’s laws of motion – could not be applied.
Ruse’s response misses its target. Ruse construes Plantinga’s objection to be aimed at (iii), “the claim that scientific understanding involves reference to law.” This, however, is false. The appeal to the big bang was actually proposed as a counter example to (ii), Ruse’s contention that science deals only with repeatable events. The common line of argument Ruse responds to is not the line of argument Plantinga actually offers.
Moreover, Ruse’s response fails to address Plantinga’s counter example completely. Plantinga’s counter example was based on big bang cosmology. Instead of showing that his definition can accommodate the big bang, Ruse instead notes that other people (not Plantinga) have offered a different counter-example, the extinction of the dinosaurs, and that this different counter example is unsuccessful. Ruse may well be correct; the extinction of the dinosaurs is not a valid counter-example to (iii) however, Plantinga never said it was. What he said was that the possibility that the big bang is unrepeatable is a counter-example to (ii) and to this line of argument Ruse says nothing.
Requirement of Being Law-Governed
Of course Plantinga does offer a response to (iii), the idea that science, by definition, deals only with what is governed by law but his argument against this is very different to an appeal to the extinction of the dinosaurs. Plantinga turns to the issue of being law-governed in the next paragraph and raises quite a different objection to this,
Consider next the property of being governed by law. The first point, here, would be that the very existence of natural law is controversial; Bas van Fraassen, for example, has given an extended and formidable argument for the conclusion that there are no natural laws. There are regularities, of course, but a regularity is not yet a law; a law is what is supposed to explain and ground a regularity. Furthermore, a law is supposed to hold with some kind of necessity, typically thought to be less stringent than broadly logical necessity, but necessity nonetheless. … So suppose van Fraassen is right and there are no natural laws: would it follow by definition that there isn’t any science? That seems a bit strong.
Plantinga’s point is that some empiricists (in particular, Bas van Fraassen) argue that there are not any natural laws, there are only regularities. Regardless of whether one agrees with van Frassen or not, even if he is correct it clearly would not follow that science does not exist. This entails that the existence of science does not depend on the existence of laws of nature; hence it is a mistake to define the former in terms of the latter.
Ruse’s response is as follows,
Now, whilst I am the last per son to belittle the formidable philosophical powers of Bas van Fraassen – as eminent in the field of the philosophy of quantum mechanics as Plantinga is in the field of the philosophy of religion – what is being extrapolated here is far stronger than van Fraassen or any one else would want (should want) to claim. Certainly there are questions about how one might interpret the necessity of laws: I myself have al lowed that already. But neither van Fraassen, nor any one else is going to deny that there are certain sorts of regularities of some kind and that these are pre -supposed in the activity of science.
Here Ruse states the existence of science does not presuppose the existence of natural laws, it merely presupposes regularities in nature and this is compatible with the empiricist critiques of laws of nature. The problem is that this explicitly contradicts Ruse’s definition. Ruse states that science deals only with the natural, the repeatable and that which is governed by law. In elucidating this Ruse states that science is “an approach to the empirical world that demands understanding in terms of unbroken law. That is to say, understanding in terms of regularities, which in some way or another we feel are more than mere contingencies, but rather part of the necessary succession of the empirical world.” As Ruse defines science then it presupposes more than mere regularities. This position requires that these be necessary in some sense and it is precisely this understanding of laws of nature that empiricists, such as van Fraassen, do criticise.
Ruse appears to be in a dilemma; if he accepts natural laws as necessary in some sense then his argument is subject to the objection Plantinga raises. Some empiricists reject the existence of laws so understood but even if they are correct it would be erroneous to claim that science did not exist. If Ruse contends that science need only presuppose regularities then his definition is false because his definition states science demands an understanding in terms of a necessity over and above mere regularity. It seems then that Ruse’s definition of science is problematic; if this is the case, attempts to argue for methodological naturalism on the basis of such a definition are unsound.
 Michael Ruse Darwinism Defended (Reading, MA: Addison -Wesley, 1982) 322.
 Alvin Plantinga “Religion and Science” Stanford Encyclopedia of Philosophy accessed 8 December 2009.
 Michael Ruse “Methodological Naturalism Under Fire” South African Journal of Philosophy 24 (1) 2005 47.
 Alvin Plantinga “Methodological Naturalism” Perspectives on Science and the Christian Faith 49 (September 1997).
 Ruse, above n4, 48.