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Single Idea 14607

[filed under theme 4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / d. System T ]

Full Idea

System T is a normal modal system augmented with the reflexivity-generating axiom □p→p, and is, I think, the best modal logic for modeling lawhood.

Gist of Idea

T adds □p→p for reflexivity, and is ideal for modeling lawhood

Source

Jonathan Schaffer (Causation and Laws of Nature [2008], n46)

Book Ref

'Contemporary Debates in Metaphysics', ed/tr. Sider/Hawthorne/Zimmerman [Blackwell 2008], p.104

A Reaction

Schaffer shows in the article why transitivity would not be appropriate for lawhood.

The 4 ideas with the same theme [version imposing one condition on accessibility]:

16960 If possibilitiy is relative, that might make accessibility non-transitive, and T the correct system [Dummett]
14669 For metaphysics, T may be the only correct system of modal logic [Salmon,N]
9744 The system T has the 'reflexive' conditon imposed on its accessibility relation [Fitting/Mendelsohn]
14607 T adds □p→p for reflexivity, and is ideal for modeling lawhood [Schaffer,J]