4 ideas
15927 | Definition just needs negation, known variables, conjunction, disjunction, substitution and quantification [Weyl, by Lavine] |
20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
9567 | Maths deals with quantities of physical significance, ignoring irrelevant features [Geroch] |
10246 | The limit of science is isomorphism of theories, with essences a matter of indifference [Weyl] |