I'd intended this as a comment on another answer, but apparently I'm too new for comments? So if this is the wrong spot hopefully they'll move this.
I have some experience with metaphysics, less with philosophy of mind, but this has always seemed unclear to me -- you see discussions of mental states that contrast unconscious processes like breathing with conscious process like, for example deliberation.
I just read on another post that surprise and anger are described as mental states, sometimes in the literature it seems like these are things that mental states are, but sometimes they seem like properties that mental states have. So, for example, deliberation might be angry, but it couldn't be anger. So are deliberation and anger thought to be just different kinds of mental states, or is there some other relation between them?
I've read that representational content is 'fundamental' to mental states, but they never go all the way to differentiate between the content on your mental sketchboard, and the content in your view (for example the sandwich on the table that's working it's way into my mind as I try to figure out what to type). So are these also mental states?
I've been reading a thing about mental states supervening on other states, but realised I've never been sure just what a mental state exactly is, so I'd appreciate any wisdom on this, thanks.