When to use would and when to use could

Jim wrote: Do you seriously not know the difference between "X means Y" and "X sometimes contains the meaning of Y within it"?

That was the point of my posting, Jim. I believe that this has been misanalysed. I believe that has no connection to , none at all. Normally, because double modals are not allowed in English, when one chooses to use or , with modal meanings that are decidedly different from , a change has to be made to a periphrastic modal, which in this case is .

We disagree. It isn't the end of the world. I can live with it and I think you can too.

I'm not sure anyone has actually compiled a set of "rules"

There are many good books (and not so good books) on modal logic. Works by David Lewis such as On the plurality of worlds and a general search on "modal logic" would yield decent results.

eq

Hi, eq,

My reference to rules was to rules found in elementary textbooks of English as a foreign language. You know the sort of thing: Subjects and verbs must agree in number. How to use apostrophe-S. I wasn't expecting students to study mathematics or anything quite so rigorous as you are suggesting!

I see a distinct difference between "modal logic" with its P(x) = ~N(~x), etc. and a "rule" which helps a student decide how to fill in the blank below.

I thought I _______ go to the party with Tim. (could, would, may, might, will, can, ...)

Even if there is a relationship between the formulas and the practical choices, it's not clear to me that a mastery of one would result in a mastery of the other.

Jim

Eq: modals can be inflected for tense but only syntactic tense.

Excellent point, Eq, and it feeds well into the discussion, but I'm not sure every one here is familiar with the term syntactic tense.