40 ideas
14027 | If we are to use words in enquiry, we need their main, unambiguous and uncontested meanings [Epicurus] |
13838 | A decent modern definition should always imply a semantics [Hacking] |
14040 | Observation and applied thought are always true [Epicurus] |
13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
18812 | Split out the logical vocabulary, make an assignment to the rest. It's logical if premises and conclusion match [Tarski, by Rumfitt] |
13344 | X follows from sentences K iff every model of K also models X [Tarski] |
13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
13343 | A 'model' is a sequence of objects which satisfies a complete set of sentential functions [Tarski] |
13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
14028 | Nothing comes to be from what doesn't exist [Epicurus] |
14029 | If disappearing things went to nothingness, nothing could return, and it would all be gone by now [Epicurus] |
14030 | The totality is complete, so there is no room for it to change, and nothing extraneous to change it [Epicurus] |
14048 | Astronomical movements are blessed, but they don't need the help of the gods [Epicurus] |
14044 | The perceived accidental properties of bodies cannot be conceived of as independent natures [Epicurus] |
14045 | Accidental properties give a body its nature, but are not themselves bodies or parts of bodies [Epicurus] |
14046 | A 'body' is a conception of an aggregate, with properties defined by application conditions [Epicurus] |
14047 | Bodies have impermanent properties, and permanent ones which define its conceived nature [Epicurus] |
14039 | Above and below us will never appear to be the same, because it is inconceivable [Epicurus] |
14050 | We aim to dissolve our fears, by understanding their causes [Epicurus] |
14037 | Atoms only have shape, weight and size, and the properties which accompany shape [Epicurus] |
6010 | Illusions are not false perceptions, as we accurately perceive the pattern of atoms [Epicurus, by Modrak] |
14041 | The soul is fine parts distributed through the body, resembling hot breath [Epicurus] |
14042 | The soul cannot be incorporeal, because then it could neither act nor be acted upon [Epicurus] |
13345 | Sentences are 'analytical' if every sequence of objects models them [Tarski] |
14032 | Totality has no edge; an edge implies a contrast beyond the edge, and there can't be one [Epicurus] |
14033 | Bodies are unlimited as well as void, since the two necessarily go together [Epicurus] |
14034 | There exists an infinity of each shape of atom, but the number of shapes is beyond our knowledge [Epicurus] |
14035 | Atoms just have shape, size and weight; colour results from their arrangement [Epicurus] |
14038 | There cannot be unlimited division, because it would reduce things to non-existence [Epicurus] |
14049 | We aim to know the natures which are observed in natural phenomena [Epicurus] |
14043 | The void cannot interact, but just gives the possibility of motion [Epicurus] |
14031 | Space must exist, since movement is obvious, and there must be somewhere to move in [Epicurus] |
14036 | There are endless cosmoi, some like and some unlike this one [Epicurus] |