What is LOT?

Same idea as Classical AI post. So what is the Language of Thought Hypothesis?

There is a mental language that we all tap into to produce thoughts. The lowest level of processing going on is at an atomic or symbolic level (probably lower level stuff than words and letters). But the number of little symbols we have access to are finite. The symbols however are able to combine according to certain mentalese rules (syntax) forming more complex symbols out of the ‘primatives’. It is the relation one has with a particular complex symbol or proposition that determines its meaning. For instance, the proposition ‘It will rain tomorrow’ alone has syntax and semantics (content) but no meaning in the world. It is only when you realise a token (represent content in your brain) of the symbol/proposition in a certain way that it has meaning directed back in or towards the world in which it exists, eg. ‘I believe it will rain tomorrow.’ This is a propositional attitude which has intentionality or ‘aboutness’. Further, not only do these propositional attitudes combine to form more complex ones, eg. PA ‘P’ combines with PA ‘Q’ to form PA ‘P & Q’, but LOT maintains that the mental states of complex PAs have constituent structure. Of course, the final feature of LOT (a feature that any theory of the mental should have) is that mental states have causal properties. A certain PA will either be the cause of a particular physical event, or another mental state, or both.

This all sounds quite abstract but I think the credibility of LOT comes from empirical evidence. The main argument is from the productivity and systematicity of thought. LOT explains this nicely. Productivity is that there are endless sentences capable of being formulated by thought from only a finite set of primitives. This is accounted for by treating thought as a language. Systematicity is the feature that fills in any gaps in your ability to think thoughts related to other thoughts. That is, systematicity ensures that to be able to think ‘A likes B’ is to be able to think ‘B likes A’ regardless of truth value. This corresponds with empirical evidence and again, indicates that thought is a language. Thus, mental states are generally constitutive or compisite.