Recap What is interactionist dualism? Does PD have the same problem as SD in relation to Elisabeth’s criticism? How does Chalmers respond to the objection that we can’t give an account of how mental properties would cause physical effects? How would Chalmers respond to the empirical issues with ID?

In two minutes, list as many things as you can that are causally related. Highlight the ones where the causes and effect are nothing alike.

Learning objective: To understand why Broad and Hume defend interactionism, and to evaluate whether their defences succeed.

C. D. Broad (1887 – 1971) “If the unlikeness of draughts and colds in the head does not prevent one from admitting a causal connexion between the two, why should the unlikeness of volitions and voluntary movements prevent one from holding that they are causally connected?’ What is he saying? Objectors to interactionism assume that for 2 things to interact they must have common properties or be similar in some way. Broad disagrees.

In support of SD The dissimilarity between mind and body does not mean that we must claim that they cannot be causally related. How convincing is this defence? Would it work as a defence against interactionist property dualism?

David Hume Defends/objects to interactionism. What do you know about Hume? Based on the fact he is an empiricist/rationalist, what might he say about interactionism? We cannot/can make a priori judgements about what can or cannot be causally related. Causal relations can only be discovered by empirical investigation. If we encounter an object for the first time we can’t work out from reasoning alone what its causal powers are – we need experience of it to discover its cause. Relation between cause and effect is therefore contingent/necessary. One event has no necessary relation to the idea of its effect – it is arbitrary. But where experience provides us with repeated occasion where 2 things are connected, we can say they are causally related.

So, there can be nothing in principle that prevents us supposing that ________events can cause __________events. If we have a conjunction between acts of will and actions, we have a basis of establishing a causal connection – and this is all we have. It is by experience that we learn which parts of the body we can move by volition. Some we can’t. So empirical evidence supports causal interaction. This is all we need. So no a priori reasoning to the contrary can carry any weight. How far do you agree with Hume? How does this work with PD? Is it a better/worse defence for interactionism when applied to PD or SD?

Orange book pp Remind yourself of the objections to interactionism that we looked at in relation to SD. Are they more /less convincing when applied to PD? Can the PD respond more convincingly to the objections?