On the discussion related to the question here, there seemed to be many disagreements between users in regards to identity theory and its implications on whether psychophysical harmony needs explanation.
As a refresher,
Psychophysical harmony consists in the fact that experiences are correlated with physical states and with one another in strikingly fortunate ways.
For example,
C fibers firing cause pain. However, the intrinsic probability of this is super low. It’s just as intrinsically likely that C fibers firing would cause pleasure, or the taste of hummus. But the vast majority of possible psychophysical laws would involve disharmony between the mental and the physical.
One of the top comments in that question argued that this is not surprising under reductive materialism which seemed to link to an article about identity theory. So what exactly is identity theory?
From the SEP,
The identity theory of mind holds that states and processes of the mind are identical to states and processes of the brain.
What does identical mean here? Does it mean that it reduces to physical processes of the brain or that they are literally the same? If the latter, I’m having trouble making sense of this.
Secondly, a user by the name of @Dcleve in a discussion with @NotThatGuy argued that many test cases have shown this to be false: for example, a lot of our brain processes are unconscious. Would he be correct? In the article on SEP regarding the subject,
Some philosophers hold that though experiences are brain processes they nevertheless have fundamentally non-physical, psychical, properties, sometimes called ‘qualia’. Here I shall take the identity theory as denying the existence of such irreducible non-physical properties
So this denies that there are such thing as non physical properties. So what do identity theorists classify their qualia as? Do they just assert that these experiences are physical? But isn’t consciousness already defined as non physical? Any clarity would be appreciated.