Fodor developed his idea of language of thought (representational account of propositional attitudes) from Brentano's ideas of intentionality. At the same time Daniel Dennett criticised the Fodor's idea of "representationalism". His most damaging criticism was the tacit beliefs objection. So my question is here how did Fodor defend his idea against Daniel Dennett criticism?
First of all Dennett's objection is to the plausibility of the LoT, not its possibility. But I think he has overlooked other instances of language in our world: in computing and in genetic processing.
He complains that we attribute belief to people based on observation and modeling, and that we are equally likely to attribute them to objects like computers. Our attribution of those things to computers is obviously false, so there is no good reason to believe that these things exist when we attribute them to other humans.
They might very well exist only for observers, and not in the observed thinker. We attribute beliefs to ourselves when we observe our own behavior or our own thinking and work backward to what must have caused it. So a belief might only exist, really, once it has caused something to happen, either a linguistic trace in the thinker, or an action that demonstrates his decisions, which we then analyze and trace to a belief.
But the LoT insists that the thought should come first and that the belief itself must be made of something linguistic.
Fodor himself directly attacks the idea that something severely different than a language could fit into place so well. That seems circular without some deeper basis. For instance, it is clear that at a certain level of detail, this good fit arises from a very dissimilar representation. At some level those rules are recorded in a way that contains no element of language. Nerve potentials reach a given bias threshold and fire, nothing discrete or grammatical going on. But I don't think that immediate contradiction to Fodor's argument is very meaningful.
In Dennet's world, beliefs, like quantum particles, really do not exist until observed, except as mere tendencies of potentials. But what determines those tendencies of potentials?
Unlike with quantum particles, we presume that human behavior is caused. It arises out of the matrix of the brain and body by bringing together information. Almost nothing we observe in human activity is the result of a single neural firing. The potentials that result in an act come together according to rules.
Stepping back, claiming that no language was involved in setting those thresholds is like insisting that one can load a functioning program into a computer by controlling the individual electrical potentials at gates, without using any machine language, programming or compiling mechanism.
That is not very tractable. In fact, for humans it proved impossible very early in the history of computing. Even Dennett's metaphor for how the negotiation process for establishing a usable pattern of information, the human bodies equivalent of compiling a program, involves 'drafts' of 'messages'. He intends for this to be highly metaphorical, but I don't think that it has to be. The rules that allow those ideas to negotiate themselves into a narrative are probably mediated by some mechanical process involving code markers and deduction rules.
As motivation, the component executing this process, involving protein construction and other molecular processes, is guided by encoded messages, written in RNA. This is not a metaphor, amino-acid markers are quite obviously letters in a language and they are transformed via rules encoded into the pieces of RNA that construct the proteins that read and write them. So even evolution seems to have decided that at some level of complexity, coordinating this volume of information requires encoding and rule-following.
To then see the notion that a language is involved in coordinating the process of thought as implausible seems biased. However indirectly constructed the working of that language is, it can be seen as the 'language in which thought is done'.
So, from that position Fodor is oversimplifying grossly, but he is not absolutely wrong. There should be some kind of real, non-metaphorical, language representation that guides the development of new thoughts in some way. Because nature and humans both, when faced with other equally complex situations did, in fact decide to address them with codes and rules.
In INTENTIONALITY AND PROPOSITIONAL ATTITUDES Lycan gives a nice summary of Fodor's representational theory and Dennett's objection, with rebuttals and follow-ups.
"What the representational says is only this: Propositional attitudes are like sentences in that (i) they have conceptual parts, (ii) they have semantical properties such as truth values and entailments, (iii) they have a grammar or syntax by which their conceptual parts are compounded into whole propositional contents, and (iv) they are physically realized in the brain...
(Dennett): Tacit propositional attitudes (the belief that New York is not on the moon, the desire that one not be beaten to death by angry insurance adjusters from northern Tibet, the hope that one will be alive 30 seconds from now).
Reply: The Representational theory applies only to “occurrent” states, not to tacit attitudes.
Rejoinder: But what about the tacit attitudes? You said the Representational theory is a theory of the propositional attitudes, but now you’re saying it’s a theory of only a few of them.
Standard move: Tacit attitudes are only dispositions to be in the corresponding occurrent states (...you tacitly believe that I am less than 35 feet tall because you have judged that I am only about so tall, which entails that I am less than 35 feet tall)...
Suggestion: We may not need to solve that problem. How about letting the tacit beliefs be those logical consequences of “occurrent beliefs” or judgements, that are not themselves occurrent? ...The tacit beliefs are implicit in judgements, by being logically contained in them.
That’s as good an idea as I know. But it faces two difficulties.
First difficulty: Intuitively, we don’t want to count every proposition that’s entailed by one of my judgements as a tacit belief of mine. To take the most extreme case, every logical tautology is entailed by every judgement I make, but it seems wrong to say that I even tacitly believe that blah-blah, where blah-blah abbreviates a gigantic tautology...
Second difficulty: It would not always be easy to identify the particular judgement of which a given tacit belief is supposed to be a logical consequence..."