42 ideas
| 1597 | Thales was the first western thinker to believe the arché was intelligible [Roochnik on Thales] |
| 22338 | An unexamined life can be virtuous [Murdoch] |
| 22337 | Philosophy must keep returning to the beginning [Murdoch] |
| 23563 | Philosophy moves continually between elaborate theories and the obvious facts [Murdoch] |
| 7786 | Propositional logic handles negation, disjunction, conjunction; predicate logic adds quantifiers, predicates, relations [Girle] |
| 7798 | There are three axiom schemas for propositional logic [Girle] |
| 7799 | Proposition logic has definitions for its three operators: or, and, and identical [Girle] |
| 7797 | Axiom systems of logic contain axioms, inference rules, and definitions of proof and theorems [Girle] |
| 7794 | There are seven modalities in S4, each with its negation [Girle] |
| 7793 | ◊p → □◊p is the hallmark of S5 [Girle] |
| 7795 | S5 has just six modalities, and all strings can be reduced to those [Girle] |
| 7787 | Possible worlds logics use true-in-a-world rather than true [Girle] |
| 7788 | Modal logic has four basic modal negation equivalences [Girle] |
| 7796 | Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle] |
| 7789 | Necessary implication is called 'strict implication'; if successful, it is called 'entailment' [Girle] |
| 7790 | If an argument is invalid, a truth tree will indicate a counter-example [Girle] |
| 7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
| 7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
| 3013 | Nothing is stronger than necessity, which rules everything [Thales, by Diog. Laertius] |
| 7792 | A world has 'access' to a world it generates, which is important in possible worlds semantics [Girle] |
| 22591 | We know perfection when we see what is imperfect [Murdoch] |
| 22709 | We should first decide what are the great works of art, with aesthetic theory following from that [Murdoch] |
| 22341 | Literature is the most important aspect of culture, because it teaches understanding of living [Murdoch] |
| 22715 | Great art proves the absurdity of art for art's sake [Murdoch] |
| 22714 | Because art is love, it improves us morally [Murdoch] |
| 22347 | Appreciating beauty in art or nature opens up the good life, by restricting selfishness [Murdoch] |
| 22712 | Art and morals are essentially the same, and are both identical with love [Murdoch] |
| 22339 | Love is a central concept in morals [Murdoch] |
| 22348 | Ordinary human love is good evidence of transcendent goodness [Murdoch] |
| 22713 | Love is realising something other than oneself is real [Murdoch] |
| 22343 | If I attend properly I will have no choices [Murdoch] |
| 22349 | Art trains us in the love of virtue [Murdoch] |
| 22340 | It is hard to learn goodness from others, because their virtues are part of their personal history [Murdoch] |
| 22350 | Only trivial virtues can be possessed on their own [Murdoch] |
| 22346 | Moral reflection and experience gradually reveals unity in the moral world [Murdoch] |
| 20765 | Man is a brave naked will, separate from a background of values and realities [Murdoch] |
| 22342 | Kantian existentialists care greatly for reasons for action, whereas Surrealists care nothing [Murdoch] |
| 22351 | Only a philosopher might think choices create values [Murdoch] |
| 1494 | Thales said water is the first principle, perhaps from observing that food is moist [Thales, by Aristotle] |
| 1713 | Thales must have thought soul causes movement, since he thought magnets have soul [Thales, by Aristotle] |
| 22345 | Moral philosophy needs a central concept with all the traditional attributes of God [Murdoch] |
| 1742 | Thales said the gods know our wrong thoughts as well as our evil actions [Thales, by Diog. Laertius] |