In a nutshell, Professor Farkas argues that meaning is in the head after all. That’s the “internalist” position that most academic philosophers have rejected in favor of a newer position called “externalism”. That’s the idea that, in Hilary Putnam’s well-known phrase, “meaning ain’t in the head”.
Putnam argued for his position by describing a thought experiment in which two guys named Oscar are exactly the same in every way and live on two Earth’s that seem to be the same in every way too. They both call the clear, tasteless liquid around them “water”, but it’s years before anyone on either planet has figured out what water is made of. The thing is that, without anyone knowing it yet, the water on Earth is H2O (as we now know) but on Twin Earth it’s XYZ (i.e. not H2O). The question is: “What do Oscar and his twin mean by the word “water”?” Putnam and the other externalists think that they mean different things when they each use that word. (You can read more about the thought experiment here.)
Farkas, on the other hand, thinks that the great 17th century philosopher René Descartes was basically right. Meaning is a psychological phenomenon. If Oscar and his twin on that other Earth have the exact same conscious thoughts about what they both call “water”, the word has the same meaning for both of them, regardless of what water’s (unknown) molecular composition happens to be.
Here’s the last paragraph of the book:
I have defended a certain conception of the mental, one I regard as developing Descartes’s fundamental insight about the mind: that the mind is essentially revealed from the subject’s point of view. I have shown that this conception lies at the heart of contemporary internalist theories. I have considered an objection against the notion of internally individuated content [or meaning] and found it wanting. Hopefully, we can now give back the subject and her point of view the proper place they deserve.
I also accept the internalist position, which is probably the main reason I enjoyed the book. The author’s discussion of sense and reference was especially helpful, but it’s not a book for anyone unfamiliar with the topic.