A topic of continued interest (primarily by(?) Geoff Pullum) is linguification, or the expression of a particular idea or argument in terms of language. A couple years ago I wrote about one particular type of linguification that often takes the form of
You rarely hear X and Y in the same sentence
and which expresses, basically, X and Y are really different and totally unrelated. In case X is a modifier of Y, then it means Y is anything but properly described by X (e.g., you never hear “politician” and “honest” within three words of each other).
In the June 2008 issue of Language, Frederick (Fritz) Newmeyer writes, in a footnote:
The late Jim McCawley wrote somewhere that he can always pick out theoretical linguists at academic cocktail parties. We are the ones who talk about the Fibonacci sequence, the laws of thermodynamics, and Romance clitic climbing, all in the same sentence.
This reflects what I guessed was a folk theory of discourse, one part of which is the idea that sentences have only a single topic, and that nothing is present in the scope of negation (e.g., “studying Romance clitic climbing clearly has nothing to do with the laws of thermodynamics, which is just as well considering that I know nothing about the latter”). This particular form of linguification relies on the idea that if any concepts are mentioned in the same sentence, this indicates at least that the speaker is interested in all three topics, and perhaps even that the speaker is somehow arguing for a significant relation between them. (Or perhaps just that they are concept-dropping in order to impress their colleagues).