31 ideas
| 17641 | Discoveries in mathematics can challenge philosophy, and offer it a new foundation [Russell] |
| 17638 | If one proposition is deduced from another, they are more certain together than alone [Russell] |
| 17632 | Non-contradiction was learned from instances, and then found to be indubitable [Russell] |
| 9821 | A definition need not capture the sense of an expression - just get the reference right [Frege, by Dummett] |
| 9585 | Since every definition is an equation, one cannot define equality itself [Frege] |
| 11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
| 11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
| 11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
| 17629 | Which premises are ultimate varies with context [Russell] |
| 17630 | The sources of a proof are the reasons why we believe its conclusion [Russell] |
| 17640 | Finding the axioms may be the only route to some new results [Russell] |
| 17446 | Counting rests on one-one correspondence, of numerals to objects [Frege] |
| 9582 | Husserl rests sameness of number on one-one correlation, forgetting the correlation with numbers themselves [Frege] |
| 17627 | It seems absurd to prove 2+2=4, where the conclusion is more certain than premises [Russell] |
| 9586 | In a number-statement, something is predicated of a concept [Frege] |
| 9580 | Our concepts recognise existing relations, they don't change them [Frege] |
| 9589 | Numbers are not real like the sea, but (crucially) they are still objective [Frege] |
| 17628 | Arithmetic was probably inferred from relationships between physical objects [Russell] |
| 9577 | The naïve view of number is that it is like a heap of things, or maybe a property of a heap [Frege] |
| 9578 | If objects are just presentation, we get increasing abstraction by ignoring their properties [Frege] |
| 17637 | The most obvious beliefs are not infallible, as other obvious beliefs may conflict [Russell] |
| 17639 | Believing a whole science is more than believing each of its propositions [Russell] |
| 17631 | Induction is inferring premises from consequences [Russell] |
| 9581 | Many people have the same thought, which is the component, not the private presentation [Frege] |
| 9579 | Disregarding properties of two cats still leaves different objects, but what is now the difference? [Frege] |
| 9587 | How do you find the right level of inattention; you eliminate too many or too few characteristics [Frege] |
| 9588 | Number-abstraction somehow makes things identical without changing them! [Frege] |
| 9583 | Psychological logicians are concerned with sense of words, but mathematicians study the reference [Frege] |
| 9584 | Identity baffles psychologists, since A and B must be presented differently to identify them [Frege] |
| 11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
| 17633 | The law of gravity has many consequences beyond its grounding observations [Russell] |