106 ideas
7001 | If you begin philosophy with language, you find yourself trapped in it [Heil] |
7037 | Parsimony does not imply the world is simple, but that our theories should try to be [Heil] |
7038 | A theory with few fundamental principles might still posit a lot of entities [Heil] |
7004 | The view that truth making is entailment is misguided and misleading [Heil] |
13689 | 'Theorems' are formulas provable from no premises at all [Sider] |
13705 | Truth tables assume truth functionality, and are just pictures of truth functions [Sider] |
13706 | Intuitively, deontic accessibility seems not to be reflexive, but to be serial [Sider] |
13710 | In D we add that 'what is necessary is possible'; then tautologies are possible, and contradictions not necessary [Sider] |
13711 | System B introduces iterated modalities [Sider] |
13708 | S5 is the strongest system, since it has the most valid formulas, because it is easy to be S5-valid [Sider] |
13712 | Epistemic accessibility is reflexive, and allows positive and negative introspection (KK and K¬K) [Sider] |
13714 | We can treat modal worlds as different times [Sider] |
13720 | Converse Barcan Formula: □∀αφ→∀α□φ [Sider] |
13718 | The Barcan Formula ∀x□Fx→□∀xFx may be a defect in modal logic [Sider] |
13723 | System B is needed to prove the Barcan Formula [Sider] |
13715 | You can employ intuitionist logic without intuitionism about mathematics [Sider] |
7035 | God does not create the world, and then add the classes [Heil] |
13678 | The most popular account of logical consequence is the semantic or model-theoretic one [Sider] |
13682 | Maybe logical consequence is impossibility of the premises being true and the consequent false [Sider] |
13680 | Maybe logical consequence is a primitive notion [Sider] |
13679 | Maybe logical consequence is more a matter of provability than of truth-preservation [Sider] |
13722 | A 'theorem' is an axiom, or the last line of a legitimate proof [Sider] |
13696 | When a variable is 'free' of the quantifier, the result seems incapable of truth or falsity [Sider] |
13700 | A 'total' function must always produce an output for a given domain [Sider] |
13703 | λ can treat 'is cold and hungry' as a single predicate [Sider] |
13688 | Good axioms should be indisputable logical truths [Sider] |
13687 | No assumptions in axiomatic proofs, so no conditional proof or reductio [Sider] |
13691 | Induction has a 'base case', then an 'inductive hypothesis', and then the 'inductive step' [Sider] |
13690 | Proof by induction 'on the length of the formula' deconstructs a formula into its accepted atoms [Sider] |
13685 | Natural deduction helpfully allows reasoning with assumptions [Sider] |
13686 | We can build proofs just from conclusions, rather than from plain formulae [Sider] |
13697 | Valuations in PC assign truth values to formulas relative to variable assignments [Sider] |
13684 | The semantical notion of a logical truth is validity, being true in all interpretations [Sider] |
13704 | It is hard to say which are the logical truths in modal logic, especially for iterated modal operators [Sider] |
13724 | In model theory, first define truth, then validity as truth in all models, and consequence as truth-preservation [Sider] |
13698 | In a complete logic you can avoid axiomatic proofs, by using models to show consequences [Sider] |
13699 | Compactness surprisingly says that no contradictions can emerge when the set goes infinite [Sider] |
13701 | A single second-order sentence validates all of arithmetic - but this can't be proved axiomatically [Sider] |
7017 | The reductionist programme dispenses with levels of reality [Heil] |
7003 | There are levels of organisation, complexity, description and explanation, but not of reality [Heil] |
7045 | Realism says some of our concepts 'cut nature at the joints' [Heil] |
7065 | Anti-realists who reduce reality to language must explain the existence of language [Heil] |
13692 | A 'precisification' of a trivalent interpretation reduces it to a bivalent interpretation [Sider] |
13693 | A 'supervaluation' assigns further Ts and Fs, if they have been assigned in every precisification [Sider] |
13695 | Supervaluational logic is classical, except when it adds the 'Definitely' operator [Sider] |
13694 | We can 'sharpen' vague terms, and then define truth as true-on-all-sharpenings [Sider] |
7020 | Concepts don't carve up the world, which has endless overlooked or ignored divisions [Heil] |
13683 | A relation is a feature of multiple objects taken together [Sider] |
7007 | I think of properties as simultaneously dispositional and qualitative [Heil] |
7015 | A predicate applies truly if it picks out a real property of objects [Heil] |
7042 | A theory of universals says similarity is identity of parts; for modes, similarity is primitive [Heil] |
7023 | Powers or dispositions are usually seen as caused by lower-level qualities [Heil] |
7025 | Are a property's dispositions built in, or contingently added? [Heil] |
7034 | Universals explain one-over-many relations, and similar qualities, and similar behaviour [Heil] |
7039 | How could you tell if the universals were missing from a world of instances? [Heil] |
7009 | Similarity among modes will explain everthing universals were for [Heil] |
7041 | Similar objects have similar properties; properties are directly similar [Heil] |
7032 | Objects join sets because of properties; the property is not bestowed by set membership [Heil] |
7008 | Trope theorists usually see objects as 'bundles' of tropes [Heil] |
7018 | Objects are substances, which are objects considered as the bearer of properties [Heil] |
7019 | Maybe there is only one substance, space-time or a quantum field [Heil] |
7046 | Rather than 'substance' I use 'objects', which have properties [Heil] |
7047 | Statues and bronze lumps have discernible differences, so can't be identical [Heil] |
7048 | Do we reduce statues to bronze, or eliminate statues, or allow statues and bronze? [Heil] |
11976 | Aristotelian essentialism says essences are not relative to specification [Lewis] |
13702 | The identity of indiscernibles is necessarily true, if being a member of some set counts as a property [Sider] |
13721 | 'Strong' necessity in all possible worlds; 'weak' necessity in the worlds where the relevant objects exist [Sider] |
13707 | Maybe metaphysical accessibility is intransitive, if a world in which I am a frog is impossible [Sider] |
13709 | Logical truths must be necessary if anything is [Sider] |
11978 | Causal necessities hold in all worlds compatible with the laws of nature [Lewis] |
13716 | 'If B hadn't shot L someone else would have' if false; 'If B didn't shoot L, someone else did' is true [Sider] |
13717 | Transworld identity is not a problem in de dicto sentences, which needn't identify an individual [Sider] |
11979 | It doesn't take the whole of a possible Humphrey to win the election [Lewis] |
16994 | Counterpart theory is bizarre, as no one cares what happens to a mere counterpart [Kripke on Lewis] |
11974 | Counterparts are not the original thing, but resemble it more than other things do [Lewis] |
11975 | If the closest resembler to you is in fact quite unlike you, then you have no counterpart [Lewis] |
11977 | Essential attributes are those shared with all the counterparts [Lewis] |
13719 | Barcan Formula problem: there might have been a ghost, despite nothing existing which could be a ghost [Sider] |
7028 | If properties were qualities without dispositions, they would be undetectable [Heil] |
7029 | Can we distinguish the way a property is from the property? [Heil] |
7030 | Properties don't possess ways they are, because that just is the property [Heil] |
7051 | Objects only have secondary qualities because they have primary qualities [Heil] |
7044 | Secondary qualities are just primary qualities considered in the light of their effect on us [Heil] |
7052 | Colours aren't surface properties, because of radiant sources and the colour of the sky [Heil] |
7053 | Treating colour as light radiation has the implausible result that tomatoes are not red [Heil] |
7066 | If the world is just texts or social constructs, what are texts and social constructs? [Heil] |
7021 | If the world is theory-dependent, the theories themselves can't be theory-dependent [Heil] |
7026 | Science is sometimes said to classify powers, neglecting qualities [Heil] |
7060 | One form of explanation is by decomposition [Heil] |
7010 | Dispositionality provides the grounding for intentionality [Heil] |
7054 | Intentionality now has internalist (intrinsic to thinkers) and externalist (environment or community) views [Heil] |
7011 | Qualia are not extra appendages, but intrinsic ingredients of material states and processes [Heil] |
7061 | Philosophers' zombies aim to show consciousness is over and above the physical world [Heil] |
7063 | Zombies are based on the idea that consciousness relates contingently to the physical [Heil] |
7064 | Functionalists deny zombies, since identity of functional state means identity of mental state [Heil] |
7027 | Functionalists say objects can be the same in disposition but differ in quality [Heil] |
7062 | Functionalism cannot explain consciousness just by functional organisation [Heil] |
7059 | The 'explanatory gap' is used to say consciousness is inexplicable, at least with current concepts [Heil] |
7012 | If a car is a higher-level entity, distinct from its parts, how could it ever do anything? [Heil] |
7043 | Multiple realisability is actually one predicate applying to a diverse range of properties [Heil] |
7058 | Externalism is causal-historical, or social, or biological [Heil] |
7057 | Intentionality is based in dispositions, which are intrinsic to agents, suggesting internalism [Heil] |
7013 | The Picture Theory claims we can read reality from our ways of speaking about it [Heil] |
7002 | If propositions are states of affairs or sets of possible worlds, these lack truth values [Heil] |
7016 | The standard view is that causal sequences are backed by laws, and between particular events [Heil] |
7036 | The real natural properties are sparse, but there are many complex properties [Heil] |