20 ideas
| 23269 | Philosophy must start from clearly observed facts [Galen] |
| 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] |
| 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] |
| 17627 | It seems absurd to prove 2+2=4, where the conclusion is more certain than premises [Russell] |
| 17628 | Arithmetic was probably inferred from relationships between physical objects [Russell] |
| 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] |
| 23266 | The spirit in the soul wants freedom, power and honour [Galen] |
| 23219 | Stopping the heart doesn't terminate activity; pressing the brain does that [Galen, by Cobb] |
| 23264 | Philosophers think faculties are in substances, and invent a faculty for every activity [Galen] |
| 23220 | The brain contains memory and reason, and is the source of sensation and decision [Galen] |
| 23265 | The rational part of the soul is the desire for truth, understanding and recollection [Galen] |
| 19087 | The meaning or purport of a symbol is all the rational conduct it would lead to [Peirce] |
| 23268 | We execute irredeemable people, to protect ourselves, as a deterrent, and ending a bad life [Galen] |
| 17633 | The law of gravity has many consequences beyond its grounding observations [Russell] |