You have chosen 'Theory of Knowledge (2nd edn)' by Keith Lehrer, 'On Sense and Reference' by Gottlob Frege and 'On the Conservation of Force' by Hermann von Helmholtz
start again | choose another area for these texts | all the ideas for this combination of texts| All the ideas for Natural Theory, or select a subheading: |
| A. | Speculations on Nature | |
| B. | Natural Kinds | |
| C. | Causation | |
| D. | Laws of Nature |