You have chosen 'Theory of Knowledge (2nd edn)' by Keith Lehrer, 'Presidential Address of Am. Math. Soc' by Oswald Veblen and 'On the General Idea of Proof Theory' by Dag Prawitz
start again | choose another area for these texts | all the ideas for this combination of texts| All the ideas for Modality, or select a subheading: |
| A. | Necessity | |
| B. | Possibility | |
| C. | Sources of Modality | |
| D. | Knowledge of Modality | |
| E. | Possible worlds |