Scientific Naturalism and the Argument from Reason

by Saints and Sceptics

This article outlines the “argument from reason” against scientific naturalism and for theism.

1 What is Scientific Naturalism?

Scientific naturalism, or strict naturalism, is the view that the spatio-temporal universe of entities postulated by our best current (or ideal) sciences, particularly physics, is all there is (Moreland, 2012, p.284) This world-view aims to provide an event-causal, scientific account of how everything has come to be and a general ontology in which the only entities which exist are those which bear a relevant similarity to those which would characterise a completed form of physics (Moreland, 2012, pp.282-285).

If naturalism is true, all of reality can be accounted for by physics, cosmology, and the processes of evolution. The two core theories of scientific naturalism are the atomic theory of matter and evolutionary theory (Moreland, 2012, p. 285)  These scientific theories use combinatorial modes of explanation. Wholes at each level above the ground level of elementary microphysics are explained by the composition of the separable parts at lower levels. So living organisms are composed of cells; cells are composed of molecules, which in turn are composed of atoms, which are composed of subatomic parts, which are composed of microphysical entities.

Every physical event has physical causes which are sufficient to produce it; therefore, scientific naturalism subscribes to “the causal closure of the physical domain” (Goetz, 2011; Reppert,2003, p.52). Whenever we seek to explain an event or entity we need appeal only to physical laws and physical objects. This entails that we need never appeal to subjective consciousness, thoughts, plans, intentions or desires to explain the properties of any organism. The scientific naturalist can either attempt to reduce mental properties, like “intentions” and “beliefs”, to physical properties ( for example, the neuro-phsyiological states of organisms); or, the scientific naturalist might argue that mental properties supervene on, or are emergent from, physical properties. In this case mental properties would be determined by physical properties.

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2 How does Naturalism account for Rationality?

Why would a naturalist believe that our cognitive mechanisms reliably produce true beliefs? Darwinian evolution offers an explanation. Organisms with mechanisms which reliably produce true beliefs are better adapted to their environments; therefore natural selection ‘favours’ these organisms. Garvey (2007) suggests that “it is not too controversial to state that it is something about the world that determines which beliefs are true. Different ways of expressing this might include ‘true beliefs describe the world accurately, ‘true beliefs correspond to the world and so on” (Garvey, 2007, p.181).

A trait is adaptive if it helps a creature which has it survive and reproduce given the way its environment is (Garvey, 2007, p.182). If an environment contains a dangerous predator, then traits which keep organisms away from that predator are adaptive. So traits which provide animals with true beliefs will be adaptive; of course, the trait must also give the animal an appropriate propositional attitude towards that belief. So, the belief “there is a dangerous predator in the vicinity” will not be adaptive if the animal also has a desire to play with dangerous predators.

Darwinian evolution also guarantees the reliability of our inductive practices. We regularly make generalisations because we cannot treat every situation as if it is entirely new. To make generalisations we must be able to group things into categories or classes. “Only if we recognise lions as forming a class are we able to have the useful belief ‘lions are not safe to approach’” (Garvey, 2007, p.182). But there are many different ways in which we could classify things. Our inductive practices will only be reliable if we have the ability to pick out the relevant similarities between things…


Scientific Naturalism and the Argument from Reason – Saints and Sceptics