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The Table Video

Keith Ward

On Scientific Evidence for Mental-Physical Causation

Regius Professor of Divinity, University of Oxford / Fellow of the British Academy / Priest of the Church of England
July 24, 2013

Keith Ward sat down with the Biola University Center for Christian Thought in San Diego, California in July of 2013. In this clip, Ward considers whether we are in a position, scientifically, to claim that the physical domain is causally closed from mental causes.


The maturest philosophers that I know tend to say that if your conscious events are correlated with your brain events, and if your brain events are parts of a causal chain which is physically determined, how could there be any nonphysical influences on those physical processes? So, they don’t see how you could have a causal chain which included nonphysical events.

And I think my response to that would be that I don’t think they should have as much confidence in the view that there is such a thing as a closed, physical, causal chain. I don’t see that there’s much evidence that there is such a closed, causal chain. And I don’t want you to rely here simply on what happens at the subatomic level but even at the ordinary level of physical laws. It doesn’t seem to be the case that physical law our statement of laws of physics gives a complete description of all the causal factors there are involved.

Let me give you one example. Which is that it’s pretty wildly thought by physicists that there are non-local, causal factors at work in the universe so that you could have, well, John Polkinghorne puts it like this, you could have a photon coming in to existence at the other side of the universe. That would have some effect on everything in the universe. I mean, it would be an infinitesimal effect but it would be some sort of effect.

So, it isn’t possible to, I’m saying it isn’t physically possible or even logically possible given the finite nature of the human mind for us to get enough information to know every causal factor there is at work in any one point of the universe. Some philosophers used to put it like this: to know anything, you’d have to know everything.

Right? So, to fully know everything about something, you’d have to know about the total context in which it existed and we never could do that, it’s too complicated to do. So that’s one thought. That you just couldn’t ever get such information as to say, I know it’s a closed, causal framework operating here because I know every cause that’s operating in this case. I’m making an empirical claim, which I’m getting from physicists saying no, we can prove the Bell Theorem reasons that why we can prove that you couldn’t possibly know every causal.

Even the fact that we don’t know much about dark energy and dark matter and that we admit we don’t much about it, says that we can’t be sure that we know everything that’s happening. All that does is open the door to causal influences that we haven’t taken into account. And it seems to me, obvious, that there are things in empty space or in controlled conditions in laboratories where we keep as close a control on causal factors as we can, so we eliminate all personal factors in those situations and we say, well, so they’re not operating, I’ve got no trouble with that. But what about cases like the brain where we say, actually, as well as physical influences, we sometimes decide to do things.

Suppose, the best example that appeals to me is doing mathematics. Suppose you’re doing a very complicated mathematical problem and you’re solving Fermat’s Last Theorem, right? And while you’re doing that, if somebody said to you, all that’s happening is certain laws of physics like the law of gravity and shredding, as equations, and things like that are working and they’re producing you trying to solve Fermat’s Last Theorem and I think the response would be, I don’t care what the laws of physics are, what I’m trying to do is solve this theorem.

I’m trying to perform a logical operation. And it strikes me as fantastically implausible that a logical operation should correlate with laws of physics which are not operations in logic at all. Laws of physics are just regularities that happen in accordance with certain mathematical principles. They’re not laws of logic. So how on earth could you say that when you’re trying to think intelligently, that is actually just laws of physics producing these effects.

And that seems to be totally implausible. So my first point would be, we don’t know enough about laws of nature to really say there’s a closed, causal chain. There’s a lot of evidence against this being true, and we certainly know we couldn’t show that it was true. Then my second point is, it’s vastly implausible to think that performing rational or mathematical operations is something that could be totally explained just by physical laws. I think those are powerful arguments, they do seem to me to be.

And so I think there’s a very plausible case to be made that there are nonphysical, causal influences operating in the brain which are not physical. So the brain is not purely physical. The nonphysical part does have, in my dual aspect view, there are causal influences between the physical and the mental, obviously. But there are also causal influences between the mental and the physical and that seems a common sensical view and a plausible view.

And a view which I don’t think science is committed against. Perhaps I can put that point very simply by saying when somebody says that nature consists of a closed set of purely physical laws, which it could in principle be totally enumerated by human minds, I think the evidence in science is against that. [soft piano music]