On Science, Religion and Naturalism




On Naturalism

Naturalism is the worldview that the physical universe is all there is. No gods, spirits or souls. Nature is the only reality, there is nothing super-natural.

It’s helpful to distinguish between naturalism as a worldview (nature is all there is, God doesn’t exist), and naturalism as a method for scientific investigation. The former is called metaphysical or ontological or philosophical naturalism, and the latter is called methodological naturalism. Methodological naturalism is not concerned with claims about whether God exists, it simply describes the framework through which scientific investigation takes place – observation, hypothesis, testing and evidence. Any scientist following the scientific method is a methodological naturalist, but that has no bearing on whether they agree with philosophical naturalism – naturalism as a worldview. It is exactly how you can be both a scientist and a Christian.

Plantinga unpacks the link between philosophical naturalism and science:


‘Some people claim that science, taken as a whole, somehow supports or underwrites a naturalistic view of the universe, one in which there is no such person as God or any other supernatural beings. Indeed, this way of looking at the world is sometimes called the scientific worldview, or, following Peter Unger, “scientiphicalism” ‘.

Plantinga argues that the core tenets of science – quantum mechanics, general relativity or evolution – have no special connection to (philosophical) naturalism. Science is equally at home with theism.

Plantinga goes even further and concludes his book with an argument for how (philosophical) naturalism and evolution conflict, an argument that explores the reliability of our cognitive faculties.

On Evolution

Much of the apparent conflict between science and religion centers on evolution. Evolution is commonly defined as the following:

  1. Ancient earth thesis. ‘The claim that the earth is very old, around 4.5 billion years.’
  2. Progress thesis. ‘The claim that life has progressed from relatively simple to relatively complex forms.’
  3. Descent with modification thesis. The claim that offspring differ in small and subtle ways from their parents.
  4. Common ancestry thesis. The claim that ‘life originated at only one place on earth, and all subsequent life being related by descent to those original living creatures.’
  5. Naturalistic mechanism. ‘The claim that there is a naturalistic mechanism driving this process of descent with modification.’
  6. Naturalistic origins thesis. The claim that ‘life itself developed from non-living matter without any special creative activity of God by just by virtue of processes described by the ordinary laws of physics and chemistry.’

Plantinga points out that evolution is properly defined as 1-4, that 5 is best labeled Darwinism, and that 6 isn’t part of a scientific theory of evolution. 1-4 don’t in and of themselves conflict with the Christian doctrine of creation – that human beings were created in God’s image, and that God intended to create creatures of a certain kind. Charles Hodge back in 1871:

‘If God made them, it makes no difference how He made them, as far as the question of design is concerned, whether at once or by a process of evolution.’

Plantinga emphasizes that incompatibility with religion arises only with 6, with the assertion that evolution is unguided.


Plantinga takes a closer look at Darwinism and the claim that science shows evolution to be unguided in a couple chapters that examine Dawkins’ and Dennett’s arguments. Plantinga disagrees with Dawkins’ assertion that ‘the evidence of evolution reveals a universe without design’. He similarly refutes Dennett’s claim that ‘the theory of natural selection shows how every feature of the world can be the product of a blind, unforesightful, non teleological, ultimately mechanical process of differential reproduction’. Science, he argues, shows no such thing.

On Evidence

It is commonly held that to be scientific you must set aside theological belief. Scientific investigation requires a disassociation from theology. This is methodological naturalism. The scientific method excludes the metaphysical out of the gate. So far so good. However, the logical consequence is that the evidence base for scientific inquiry is different from the Christian evidence base. Science constrains itself to the physical world, theology does not. And so if science comes to conclusions that seem to conflict with religion it does not automatically provide a defeater for religion, precisely because the evidence base is different.

‘The evidence base for Simonian science is part of the Christian evidence base, but only part of it. Hence the fact that Simonian science comes to conclusions incompatible with Christian belief doesn’t provide the believer with a defeater for her belief. For the Christian, Simonian science is like truncated physics.’

Science defined this way cannot properly answer the great human questions – why does the world exist, why are we here, what is the meaning of life. In contrast, the theist has an expanded evidence base from which to explore these important questions.

‘The Christian can think of Simonian science as specifying how things look from a given perspective, how they look given a particular evidence base, an evidence base that includes only a part of the Christian evidence base… The Christian’s evidence base includes a belief in God as well as belief in the main lines of the Christian faith; the former doesn’t include these things.’

Plantinga concludes that while there may arise conflict between science defined this way – science based on methodological naturalism – and religion (in areas like evolutionary psychology and historical biblical criticism), it is an unimportant type of conflict.

‘The conclusion to draw is that there is indeed conflict between science and Christian belief in this area, but that the conflict is merely superficial, of no deep significance. There is conflict, of a sort, but it shouldn’t occasion any concern for Christians.’

On Knowledge

In his writings Dennett claims that believing in an anthropomorphic God is childish or irrational. My atheist friends would certainly agree. Plantinga writes:

‘Why does Dennett think such belief is childish or irrational (for informed adults)? As far as I can see, he proceeds as follows. First, he claims that the traditional theistic arguments – the ontological argument, the cosmological arguments, the argument from (or better, to) design – don’t work. Next, he assumes that rational belief in God would require broadly scientific evidence and proposes or rather just assumes that there isn’t any other source of warrant or rationality for belief in God or for religious beliefs generally.’

Mildly offended at the professional discourtesy, Plantinga points out a double standard:


History of philosophy asserted, Plantinga proceeds:

‘What we have here is really a special case of a topic long discussed in the history of Christian thought: the so-called problem of faith and reason. According to classical Christian belief, there are two sources of knowledge or rational opinion: faith and reason. Reason includes such faculties as perception, a priori intuition (whereby one knows truths of mathematics and truths of logic), memory, testimony (whereby one can learn from others), induction (whereby one can learn from experience) and perhaps others, such as Thomas Reid’s sympathy, whereby we know of the thoughts and feeling of other people.’

Faith, on the other hand, is a wholly different kettle of fish: according to the Christian tradition, faith is a special gift from God, not part of our ordinary epistemic equipment. Faith is a source of belief, a source that goes beyond the faculties included in reason. Its not that faith is to be contrasted with knowledge; according to John Calvin, faith “is a firm and certain knowledge of God’s benevolence towards us”. So a proposition I believe by faith can (at least according to followers of Calvin) nonetheless be something I know.’

‘…the mere fact that the deliverances of faith include propositions not among the deliverances of reason doesn’t show that there is such a conflict.’

If faith is another source of knowledge, the question becomes whether one source of knowledge (reason, or something in science based on reason) provides a defeater for another (faith). This is possible, but the evidence must be strong. Consider how perception (I saw a dog in the field) is defeated by testimony (the farmer told me that it was a sheep, he doesn’t have a dog).

For something in science to provide a defeater for faith, it must include the idea ‘that the mechanisms that produce religious belief in us are not truth aimed; they are not aimed at the production of beliefs that are true, but rather at the production of beliefs that conduce to some other end, such as securing the benefits of cooperation’. Faith results in beliefs about the world; if we are to reject faith as a reliable source of knowledge, we must show that it tends not to produce true beliefs. Plantinga claims he is aware of no such defeater. While some areas of science product conflict (like historical biblical criticism or evolutionary psychology), they begin with an evidence base that excludes the possibility that God created human beings in his image. And because the evidence base is different it ‘does not, just as such, offer a defeater for Christian belief… The conflict in question is superficial’.

On Cognition

In the final section of the book, Plantinga flips the script and outlines the evolutionary argument against naturalism. This argument has its roots in C.S. Lewis Miracles (1947) and Richard Taylor Metaphysics (1963).

‘What I will argue is that naturalism is in conflict with evolution, a main pillar of contemporary science… that one can’t sensibly accept them both… My argument will center on our cognitive faculties: those faculties, or powers, or processes that produce beliefs or knowledge in us… My argument will concern the reliability of these cognitive faculties.’

Its important to point out that Plantinga is not arguing against evolution and/or science, he is arguing that evolution + naturalism is contradictory, and that there is therefore conflict between science and naturalism.

‘… suppose you are a naturalist: you think there is no such person as God, and that we and our cognitive faculties have been cobbled together by natural selection. Can you then sensibly think that our cognitive faculties are for the most part reliable? I say you can’t. The basic idea of my argument could be put (a bit crudely) as follows. First, the probability of our cognitive faculties being reliable, given naturalism and evolution, is low… But then according to the second premise of my argument, if I believe both naturalism and evolution, I have a defeater for my intuitive assumption that my cognitive faculties are reliable. If I have a defeater for that belief, however, then I have a defeater for any belief I take to be produced by my cognitive faculties. That means that I have a defeater for my belief that naturalism and evolution are true. So my belief that naturalism and evolution are true gives me a defeater for that very belief; that belief shoots itself in the foot and is self-referentially incoherent; therefore I cannot rationally accept it. And if one can’t accept both naturalism and evolution, that pillar of current science, then there is serious conflict between naturalism and science.

The question of the reliability of our cognitive faculties has bothered philosophers for some time. Nietzsche, Nagel and others make the point that evolution optimizes for ‘the four F’s: feeding, fleeing, fighting and reproducing… Truth, whatever that is, definitely takes the hindmost.

‘What evolution underwrites is only that our behavior is reasonably adaptive to the circumstances in which our ancestors found themselves; hence it does not guarantee mostly true beliefs. Our beliefs might be mostly true, but there is no particular reason to think they would be: natural selection is interested, not in truth, but in appropriate behavior… naturalistic evolution gives us reason to doubt two things: (a) that a purpose of our cognitive systems is that of serving us with true beliefs, and (b) that they do, in fact, furnish us with mostly true beliefs.’

Darwin himself shared these concerns, what Plantinga labels “Darwin’s doubt”.


From a materialist perspective, a belief is just a physical structure in your brain, neurons connected to each other in some way. Plantinga introduces a distinction between these electro-chemical or neuro-physiological properties of a belief, and the content of the belief itself. ‘It is in virtue of having content that a belief is true or false’.

‘Given materialism, therefore, beliefs are (ordinarily) long-standing neural events. As such, the have neuro-physiological properties, but also content properties: each belief will have the property of having such and such a proposition as its content. Neuro-physiological properties are physical properties; on the other hand content properties… are mental properties.’

According to materialism, content (mental) properties are reducible to or at least determined by neuro-physiological (physical) properties.

From an evolutionary perspective there is a scale from simple organisms with simple neural structures (and presumably no beliefs) to human beings with complex neural structures and a ‘rich and varied store of beliefs… And the idea is that as you rise in the evolutionary scale, as you go through more and more complex neural structures, at a certain point there arises something we can properly call a belief, something that is true or false‘. The question Plantinga poses is ‘what is the likelihood, given evolution and naturalism (construed as including materialism), that the content thus arising is in fact true?’

From an evolutionary perspective our neurology causes adaptive behavior (survival and fitness). It so happens that this same neurology determines belief, but if our neurology evolved for a different purpose (adaptive behavior) what are the chances that the beliefs that arise are true? If the content of a given belief may equally be true or false (and given evolution we have no reason to favor one or the other), its probability is roughly 0.5. Given this probability for a particular belief, what is the probability that our cognitive faculties are reliable – that the majority of beliefs are true rather than false. If we say that 3/4 of beliefs must be true for our cognitive faculties to be reliable and we have 1000 beliefs, then the probability of this outcome is 10 -58, a very very low probability.

And with this very low probability, given evolution and naturalism, we have a defeater for the proposition that our cognitive faculties are reliable. Plantinga concludes:

‘If you have a defeater for (the proposition that our cognitive faculties are reliable), you will also have a defeater for any belief you take to be produced by your cognitive faculties, any belief that is a deliverance of your cognitive faculties. But all of your beliefs, as I’m sure you have discovered, are produced by your cognitive faculties. Therefore you have a defeater for any belief you have.’

‘…one can’t rationally accept both naturalism and current evolutionary theory; that combination of beliefs is self-defeating… Given naturalism is at least a quasi-religion, there is indeed a science religion conflict all right, but it is not between science and theistic religion: it is between science and naturalism. That’s where the conflict really lies.’

In Summary

These days, popular culture assumes that science and religion conflict. Science says ‘prove it’, religion says ‘believe’. Influential atheist thinkers and writers like Richard Dawkins and Daniel Dennett proclaim their disdain for religion loudly.

‘First, they attribute most of the ills of the world to religion: they point to the Crusades, to witch hunts, to religious wars, to intolerance, to current terrorism, and much else besides.’ ‘…[they] also claim that religious belief is unreasonable and irrational, as silly as believing in the Spaghetti Monster or Superman, or maybe even the Green Lantern. Their claims are loud and strident. They propose to deal with their opponents not by way of reasoned argument and discussion, but by way of ridicule and naked contempt.’

Christians in turn are unsure about what science means for their faith.

‘Many Christians have at least the vague impression that modern science is somehow unfriendly to religious belief; for other believers it is less a vague impression than a settled conclusion’.

Plantinga’s work offers a valuable  counter-weight to the prevailing narrative. Science, absent unscientific add-ons, is comfortably compatible with religion. Furthermore, naturalism and evolution appear to make awkward bedfellows.



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