I have just published a piece in the Institute of Art and Ideas, raising some objections to Bernardo’s Kastrup’s analytic idealism. One aspect of the disagreement between Bernardo and I is whether the following conditional is true: if physicalism is true, conscious states are epiphenomenal (i.e. have no causal effect on the physical world). Bernardo thinks it’s true; I think it’s false. I gave my reasons for thinking this in the IAI piece, but I would also like to counter-respond to some responses Bernardo raised in this blog post. I thought it better not to include this in the IAI piece, as it’s a somewhat peripheral concern. But I would recommend reading the IAI piece before reading the discussion below.
Bernardo argues for the claim <if physicalism is true, conscious states are epiphenomenal> by appealing to the work of David Chalmers on this topic, which is generally taken as canonical. Bernardo said:
“David Chalmers recapitulates the mainstream physicalist argument that, because the physical world is putatively causally-closed, phenomenal states must be physical states. In other words, because they have no causal efficacy, phenomenal states cannot exist as phenomenal states; instead, all the qualities they entail must be reducible to the quantities of physics.”
The first sentence above is correct. The second sentence, however, is not only not a correct interpretation of the first, but it contradicts the first. Again, we’re back to the logic of identity (see the IAI article). If phenomenal states are – are identical with – physical states, it follows – from Leibniz’s law – that, if physical states have causal efficacy, then phenomenal states have causal efficacy. I suspect from what he says elsewhere in the post that Bernardo will think I’m playing academic games. But the laws of logic don’t play games for anyone.
I think Bernardo may be confusing identity with elimination. Some physicalist hold that phenomenal qualities should be eliminated, in which case they don’t have causal efficacy but only because they don’t exist. The more common physicalist position is that conscious states are identical with, or wholly constituted of, physical states, in which case they have causal efficacy because they are identical with/wholly constituted of physical states. Bernardo seems to be trying to get to a middle way option for the physicalist: phenomenal states exist, but they don’t exist ‘as phenomenal states’ because they’ve been ‘reduced’. But what on earth would it mean for a phenomenal state to exist but not to exist as a phenomenal state? When physicalists say that they’ve reduced phenomenal states, they mean that phenomenal states really exist (as phenomenal states, how else would a phenomenal state exist?), but that they’re either identical with or wholly constituted of physical states.
In any case, the mainstream argument for physicalism that Chalmers is discussing claims that if dualism is true, then phenomenal states have no causal efficacy (because the physical world is causally closed), and hence that the only way we can ensure that phenomenal states have causal efficacy is if physicalism is true. I don’t buy that argument as panpsychism also gives us a way of ensuring that phenomenal states have causal efficacy (Chalmers agrees with this, which is one of the main points of the article). But the point is that Bernardo is misunderstanding what the causal closure argument is trying to show. If you don’t believe me, I recommend asking Chalmers, or any other academic philosopher working in this area, on either side of the debate. This is not a point of controversy.