If pressed, I refer to myself as a physicalist, rather than a naturalist or a materialist. All three words refer to the same view, but the words naturalism and materialism now have misleading associations.


The words nature and natural refer to the universe or cosmos, consisting of things and events describable by the natural sciences. Nature is the reality that we use our reason to try to understand and about which we try to express the truth.  I use the words nature and reality as synonyms.


Physicalists believe there are only natural things and events; there is no supernatural reality within, behind or beyond the physical universe; there are no supernatural things, such as fairies, souls, ghosts, spirits, devils, angels or gods; and supernatural events do not occur.


Physicalists do not think scientific concerns are the only ones that matter. After all, a physical description is only one of the many we use. For example, a description of chemical secretions and electrical firing in the brain would not exhaust what we want to know and say about falling in love. And such things as faith, hope, beauty and truth matter to us in ways that a scientific description would not seek to capture.


What physicalists deny is that there is any other kind of stuff in the universe apart from energy and matter, some of which constitute us: primates capable of faith, hope and love, of appreciating beauty, expressing the truth, explaining the universe, and so on. Whatever dark energy and dark matter may be, physicalists believe they are natural.


Physicalism is a theory, an explanation, based on evidence of the universality of the laws of physics. The denial that there are supernatural things and events comes directly from the evidence that things in the universe seem to conform to physical regularities, and from the absence of evidence for supernatural things and events.


Evidence from the physical sciences means we no longer need supernatural explanations for the development of the universe, the earth and life on earth, including human life. Complete understanding of origins has eluded us so far, but physicalists believe the processes were natural.


Physicalism is not a religion with communal rituals and a creed. Most of us do not call ourselves physicalists or materialists or naturalists, or even use the words at all. Most of the time we do not have to declare an identity, because we do not have to make a leap of faith in the absence of evidence. We are open to being proved wrong at any time if evidence for the supernatural appears. We see no reason to believe it will, but it is rational to be open-minded.


Factual proof involves providing evidence to justify a factual assertion, such as there is a god. And to make a factual assertion (a claim) is to accept a burden of proof. But to reject a claim is not to accept the responsibility for proving it is false. To reject a claim is not to make another claim.


For example, atheists need not claim, and do not have to prove, that there is no god. They simply reject the claim that there is. Theists who demand that atheists prove there is no god are trying to shift the burden of proof. But that burden is entirely with those who assert that there is a god. Atheism is just the absence of a belief.


In the same way, it is possible to reject claims about the supernatural without accepting the burden of proving that there are no supernatural things. And this position is called methodological naturalism or physicalism.


Of course, the physicalism I am describing goes further by asserting that there are no supernatural things, which accepts a seemingly impossible burden of proof – because how can anyone prove there are no supernatural things? And this is a strong argument against what is called philosophical naturalism or physicalism.


But this objection may arise from a misunderstanding of the nature of factual proof. To prove a factual assertion is to test it against the evidence. And a factual proof provides a sound reason for believing an assertion is true, not that it must be true.


So we can indeed prove (test the assertion) that there are no supernatural things. And it is rational to believe that things for the existence of which there is no evidence do not exist, because the absence of evidence justifies the belief. In other words, the reason for being a methodological naturalist is exactly the same as the reason for being a philosophical naturalist: the absence of evidence for the supernatural.


But of course, as always, we could be wrong, as we were about the assertion there are no black swans.


Peter Holmes

31 January 2017