But A and B don’t have to pass slabs to each other. Probably if they are building something they would pass slabs. But what if A is a Philosopher and B is a Chemist? What kind of language-game would they play? Maybe philosopher can say “Truth Serum”, and the Chemist might hand out a bottle labeled “Truth Serum” to the Philosopher. But why would the Philosopher need a truth serum for? Maybe to play another language game with The Prisoner? After injecting the serum in the Prisoner, we can imagine following language-game:
The Philosopher: Tell me… what is your name?
The Prisoner: My name is XYZ (any name would do)
The Philosopher: Did you see ABC (some other name) yesterday at the party?
The Prisoner: Yes… yes I did.
The Chemist can there express satisfaction by saying “Aha! Told you this serum would work!”, or maybe just scream “AYEEE!”, which would mean “told you this serum would work”. But maybe the Philosopher has something else on mind. A philosophical language-game!
The Philosopher:Did you see him, or do you just *think* that you saw him? Maybe it just seemed to you that you see him!
The Prisoner: I, I,….
The Philosopher: (to the Chemist) “Told you that this serum won’t work!” (Which means “AYEEE!” with an indexical?)
EDIT:I guess for a random visitor a short explanation is in order. There is a book by Wittgenstein called “Philosophical Investigations”. So, basically I chose to play a little with the title (philosopher investigating someone, how about skeptical philosopher?) and the style of the book.
A brood comb 
Nice!
But self-conscious game-playing such as this — as opposed to serious work such as building — seems to generate needless, if entertaining, complexity. Could that be considered typical of self-consciousness generally?
Robin, thanks for the comment.
If it is entertaining maybe it is not needless?
It is an interesting issue you point to re. possible complexity of speech acts/language games, but I’m not sure I understand the relation to complexity you have in mind. Can you please explain more?
It seems obvious to me that the sort of communication involved in your post with its numerous references to issues in philosophy and other areas is much, much more complex than the communication required between two people building a house. I think much of that complexity is associated with self-consciousness, which such philosophical games-playing requires, but building does not (or not to the same extent). And I assume that philosophical games-playing, while fun, like many and perhaps all actives that are intrinsically self-conscious, is dispensable, in a way that building is not.
I basically go along with Douglas Hofstadter who has a new book out called I Am A Strange Loop, and it’s probably because I’m reading it just now that I was stimulated to respond to your post in that way. I highly recommend getting hold of that book.