Property dualism and mental causation Michael Lacewing

Substance and properties A substance is an entity, a thing, that does not depend on another entity for its continued existence. –It has ‘ontological independence’. Substances are what possess properties. Properties can’t exist without substances –They depend on substances to exist. Substances persist through changes in properties.

Substance and property dualism Substance dualism: there are two sorts of substance, mind (or soul) and matter –Minds can exist independent of bodies –Mental properties are properties of a mental substance Property dualism: there is just one sort of substance, physical substance –Mental properties are properties of a material substance

Property dualism But mental properties are fundamentally distinct from physical properties –Esp. phenomenal properties of consciousness They are not ontologically dependent on physical properties –E.g. philosophical zombies: it is possible (in different possible worlds) for mental properties to be different without differences in physical properties –E.g. Jackson’s Mary: it is possible to know everything physical about the world without knowing everything about the world

Mental causation Do mental properties have ‘causal powers’? –E.g. Do thoughts cause bodily movements and other thoughts? Property dualism doesn’t face the problem of substance dualism, because mental properties are properties of physical substance But how do thoughts etc. cause physical effects? –This is no objection: any fundamental causal relationship can’t be further explained

Property dualism and science Obj: if mental properties cause physical effects, this is incompatible with science –We don’t have good evidence of this –Some interpretations of quantum mechanics support the idea that consciousness has effects

Epiphenomenalism But it is appealing to think that every physical event has a sufficient physical cause –This is compatible with property dualism if mental properties make no causal difference to the world – epiphenomenalism The claim is very counterintuitive

Epiphenomenalism Reply: it seems like mental states (e.g. pain) cause physical effects (e.g. crying) because a brain process causes both –So the mental state is correlated with the effect, but doesn’t cause it Obj: how and why would epiphenomenal properties evolve? –Reply: they are by-products of traits (brain processes) that make a difference to survival

Introspection I know I am in pain, because my belief that I am in pain is caused by my pain –If epiphenomenalism is true, my pain causes nothing I will believe that I am in pain if my brain processes are the same, even if I am not in pain –So if epiphenomenalism is true, my belief is unreliable, and not knowledge

Reply Knowledge doesn’t require direct causation –Suppose the brain state that causes pain also causes the belief that I am in pain –Then I wouldn’t (normally) have the belief without the pain – so my belief is reliable –So I know when I’m in pain

Free will and responsibility Epiphenomenalism threatens to undermine choice and responsibility for our actions –My choice is simply an effect of brain processes – how is this my choice? Choice is not mere consciousness of choosing –Choice is the brain state that causes my awareness of choosing and my awareness Other physicalist theories will have to agree that there is a physical component to choice

Compatibilism Free will is not opposed to physical causation –To have free will is for one’s choices to cause one’s actions –To choose to act is to act voluntarily –When you don’t act voluntarily, you are forced to act –But your brain is not ‘forcing you’ to act – it is you choosing to act