Axiom talk:Condensation ↔ Protraction

I think I can see where you're coming from on this — it seems like metalogic of a kind. Is it an order of abstraction further back than the concept of semantics and models in propositional logic?

JA: Exactly. From what I can tell, one of the routes by which Peirce arrived at this point of view was through his consideration of "operator variables". For example, you write an operator equation like:

$a\ O_1\ (b\ O_2\ c) = (a\ O_1\ b)\ O_2\ (a\ O_1\ c)$

Then you ask for what pairs of operators $O_1$ and $O_2$ is the equation an identity, that is, true for all the relevant values of $a, b, c$. Jon Awbrey 23:56, 10 October 2008 (UTC)