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Re: Extensional modals?

Avi, thanks, but doesn't the major premise in your temporal syllogism assume something that wasn't given?


Anyone who studies hard (S1) always gets a headache (H1)


The proposition said only that when Alex studies hard, he gets a headache, not anyone who studies hard gets a headache.

Re: Extensional modals?

Of course. That was intentional - to show you the kind of major premise you'd need to form a temporal syllogism. The major premise was not given by you, nor considered as true by me! Just intended as an example. If you want to limit the argument to Alex, then the apodosis format (the 2nd) is the correct one - but that's not, to repeat, a temporal syllogism.

Something about you (optional) logician-philosopher

Re: Extensional modals?

Thanks Avi. This modal stuff is quite tricky and will take time to understand because some of the ideas are subtle. There are so many ways of expressing propositions in English that it's sometimes hard to see whether some proposition is natural, temporal, or neither. Your writing is clear but I wish there were more concrete examples because it would make the distinctions easier to grasp. Maybe I'm just not smart enough.

Re: Extensional modals?

algojack, don't blame yourself. Even I, before I replied to your questions, had to think twice, before I could sort them out. Logic studies involve being careful and precise in language and in thought - that's what's good about it. And you are right in saying that people use modal qualifiers in somewhat mixed-up ways. E.g. we might say "People are sometimes very foolish," when we rather mean "some people are very foolish" or maybe both "some people are sometimes very foolish." Logic raises our awareness of the different possibilities of meaning and the possible errors. So, it is worth studying and practicing.

Something about you (optional) logician-philosopher

Re: Extensional modals?

Thanks for the encouragement. I'll keep reading a few pages everyday and if there's something I'm struggling with I'll post my queries and hopefully you'll be able to clarify, as you already have. Cheers,
Jack.