Combining Philosophers

Ideas for Oswald Veblen, Barbara Vetter and J.L. Mackie

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3 ideas

4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / c. System D
Deontic modalities are 'ought-to-be', for sentences, and 'ought-to-do' for predicates [Vetter]
     Full Idea: Deontic modality can be divided into sentence-modifying 'ought-to-be' modals, and predicate-modifying 'ought-to-do' modals.
     From: Barbara Vetter (Potentiality [2015], 6.9.2)
     A reaction: [She cites Brennan 1993] These two seem to correspond to what is 'good' (ought to be), and what is 'right' (ought to do). Since I like that distinction, I also like this one.
4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / h. System S5
S5 is undesirable, as it prevents necessities from having contingent grounds [Vetter]
     Full Idea: Wedgwood (2007:220) argues that S5 is undesirable because it excludes that necessary truths may have contingent grounds.
     From: Barbara Vetter (Potentiality [2015], 6.4 n5)
     A reaction: Cameron defends the possibility of necessity grounded in contingency, against Blackburn's denial of it. It's interesting that we choose the logic on the basis of the metaphysics. Shouldn't there be internal reasons for a logic's correctness?
4. Formal Logic / D. Modal Logic ML / 7. Barcan Formula
The Barcan formula endorses either merely possible things, or makes the unactualised impossible [Vetter]
     Full Idea: Subscribers to the Barcan formula must either be committed to the existence of mere possibilia (such as possible unicorns), or deny many unactualised possibilities of existence.
     From: Barbara Vetter (Potentiality [2015], 7.5)
     A reaction: It increasingly strikes me that the implications of the Barcan formula are ridiculous. Williamson is its champion, but I'm blowed if I can see why. What could a possible unicorn be like? Without them, must we say unicorns are impossible?