more from Theodore Sider

Single Idea 13712

[catalogued under 4. Formal Logic / D. Modal Logic ML / 5. Epistemic Logic]

Full Idea

Epistemic accessibility should be required to be reflexive (allowing Kφ→φ). S4 allows the 'KK principle', or 'positive introspection' (Kφ→KKφ), and S5 allows 'negative introspection' (ČKφ→KČKφ).


KK is knowing that you know (or that you don't know)

Gist of Idea

Epistemic accessibility is reflexive, and allows positive and negative introspection (KK and KČK)


Theodore Sider (Logic for Philosophy [2010], 7.2)

Book Reference

Sider,Theodore: 'Logic for Philosophy' [OUP 2010], p.185