55 ideas
15413 | With four tense operators, all complex tenses reduce to fourteen basic cases [Burgess] |
15415 | The temporal Barcan formulas fix what exists, which seems absurd [Burgess] |
15430 | Is classical logic a part of intuitionist logic, or vice versa? [Burgess] |
15431 | It is still unsettled whether standard intuitionist logic is complete [Burgess] |
15429 | Relevance logic's → is perhaps expressible by 'if A, then B, for that reason' [Burgess] |
15404 | Technical people see logic as any formal system that can be studied, not a study of argument validity [Burgess] |
15405 | Classical logic neglects the non-mathematical, such as temporality or modality [Burgess] |
15421 | Classical logic neglects counterfactuals, temporality and modality, because maths doesn't use them [Burgess] |
15427 | The Cut Rule expresses the classical idea that entailment is transitive [Burgess] |
15403 | Philosophical logic is a branch of logic, and is now centred in computer science [Burgess] |
15407 | Formalising arguments favours lots of connectives; proving things favours having very few [Burgess] |
15424 | Asserting a disjunction from one disjunct seems odd, but can be sensible, and needed in maths [Burgess] |
15409 | All occurrences of variables in atomic formulas are free [Burgess] |
15414 | The denotation of a definite description is flexible, rather than rigid [Burgess] |
15406 | 'Induction' and 'recursion' on complexity prove by connecting a formula to its atomic components [Burgess] |
15425 | The sequent calculus makes it possible to have proof without transitivity of entailment [Burgess] |
15426 | We can build one expanding sequence, instead of a chain of deductions [Burgess] |
15408 | 'Tautologies' are valid formulas of classical sentential logic - or substitution instances in other logics [Burgess] |
15418 | Validity (for truth) and demonstrability (for proof) have correlates in satisfiability and consistency [Burgess] |
15411 | We only need to study mathematical models, since all other models are isomorphic to these [Burgess] |
15412 | Models leave out meaning, and just focus on truth values [Burgess] |
15416 | We aim to get the technical notion of truth in all models matching intuitive truth in all instances [Burgess] |
15428 | The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut' [Burgess] |
10185 | Set theory is the standard background for modern mathematics [Burgess] |
10184 | Structuralists take the name 'R' of the reals to be a variable ranging over structures, not a structure [Burgess] |
10189 | There is no one relation for the real number 2, as relations differ in different models [Burgess] |
10186 | If set theory is used to define 'structure', we can't define set theory structurally [Burgess] |
10187 | Abstract algebra concerns relations between models, not common features of all the models [Burgess] |
10188 | How can mathematical relations be either internal, or external, or intrinsic? [Burgess] |
21812 | Being is the product of pure intellect [Plotinus] |
21817 | The One does not exist, but is the source of all existence [Plotinus] |
21824 | The One is a principle which transcends Being [Plotinus] |
21813 | Number determines individual being [Plotinus] |
15420 | De re modality seems to apply to objects a concept intended for sentences [Burgess] |
15419 | General consensus is S5 for logical modality of validity, and S4 for proof [Burgess] |
15417 | Logical necessity has two sides - validity and demonstrability - which coincide in classical logic [Burgess] |
15422 | Three conditionals theories: Materialism (material conditional), Idealism (true=assertable), Nihilism (no truth) [Burgess] |
15423 | It is doubtful whether the negation of a conditional has any clear meaning [Burgess] |
5506 | If soul was like body, its parts would be separate, without communication [Plotinus] |
21827 | The movement of Soul is continuous, but we are only aware of the parts of it that are sensed [Plotinus] |
21828 | A person is the whole of their soul [Plotinus] |
21809 | Our soul has the same ideal nature as the oldest god, and is honourable above the body [Plotinus] |
21825 | The soul is outside of all of space, and has no connection to the bodily order [Plotinus] |
4988 | Folk psychology may not be reducible, but that doesn't make it false [Kirk,R on Churchland,PM] |
4987 | Eliminative materialism says folk psychology will be replaced, not reduced [Churchland,PM] |
7518 | If folk psychology gives a network of causal laws, that fits neatly with functionalism [Churchland,PM] |
7519 | Many mental phenomena are totally unexplained by folk psychology [Churchland,PM] |
7520 | Folk psychology never makes any progress, and is marginalised by modern science [Churchland,PM] |
21826 | The Soul reasons about the Right, so there must be some permanent Right about which it reasons [Plotinus] |
6922 | Ecstasy is for the neo-Platonist the highest psychological state of man [Plotinus, by Feuerbach] |
21814 | How can multiple existence arise from the unified One? [Plotinus] |
21815 | Because the One is immobile, it must create by radiation, light the sun producing light [Plotinus] |
21816 | Soul is the logos of Nous, just as Nous is the logos of the One [Plotinus] |
21808 | Soul is author of all of life, and of the stars, and it gives them law and movement [Plotinus] |
21811 | Even the soul is secondary to the Intellectual-Principle [Nous], of which soul is an utterance [Plotinus] |