176 ideas
17016 | Philosophy must abstract from the senses [Newton] |
9218 | Maybe what distinguishes philosophy from science is its pursuit of necessary truths [Sider] |
14721 | Metaphysical enquiry can survive if its conclusions are tentative [Sider] |
15010 | Your metaphysics is 'cheating' if your ontology won't support the beliefs you accept [Sider] |
14977 | Metaphysics is not about what exists or is true or essential; it is about the structure of reality [Sider] |
14994 | Extreme doubts about metaphysics also threaten to undermine the science of unobservables [Sider] |
15003 | It seems unlikely that the way we speak will give insights into the universe [Sider] |
14986 | Conceptual analysts trust particular intuitions much more than general ones [Sider] |
15015 | It seems possible for a correct definition to be factually incorrect, as in defining 'contact' [Sider] |
14981 | Philosophical concepts are rarely defined, and are not understood by means of definitions [Sider] |
14992 | We don't care about plain truth, but truth in joint-carving terms [Sider] |
15012 | Orthodox truthmaker theories make entities fundamental, but that is poor for explanation [Sider] |
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] |
15023 | The Barcan schema implies if X might have fathered something, there is something X might have fathered [Sider] |
13715 | You can employ intuitionist logic without intuitionism about mathematics [Sider] |
15004 | 'Gunk' is an object in which proper parts all endlessly have further proper parts [Sider] |
14984 | Which should be primitive in mereology - part, or overlap? [Sider] |
14980 | There is a real issue over what is the 'correct' logic [Sider] |
15000 | 'It is raining' and 'it is not raining' can't be legislated, so we can't legislate 'p or ¬p' [Sider] |
15020 | Classical logic is good for mathematics and science, but less good for natural language [Sider] |
13678 | The most popular account of logical consequence is the semantic or model-theoretic one [Sider] |
13679 | Maybe logical consequence is more a matter of provability than of truth-preservation [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] |
15029 | Modal accounts of logical consequence are simple necessity, or essential use of logical words [Sider] |
13722 | A 'theorem' is an axiom, or the last line of a legitimate proof [Sider] |
15019 | Define logical constants by role in proofs, or as fixed in meaning, or as topic-neutral [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] |
13690 | Proof by induction 'on the length of the formula' deconstructs a formula into its accepted atoms [Sider] |
13691 | Induction has a 'base case', then an 'inductive hypothesis', and then the 'inductive step' [Sider] |
15001 | 'Tonk' is supposed to follow the elimination and introduction rules, but it can't be so interpreted [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] |
18079 | Newton developed a kinematic approach to geometry [Newton, by Kitcher] |
13152 | We can talk of 'innumerable number', about the infinite points on a line [Newton] |
13151 | Not all infinites are equal [Newton] |
18082 | Quantities and ratios which continually converge will eventually become equal [Newton] |
13701 | A single second-order sentence validates all of arithmetic - but this can't be proved axiomatically [Sider] |
17783 | A number is not a multitude, but a unified ratio between quantities [Newton] |
14760 | Four-dimensionalism sees things and processes as belonging in the same category [Sider] |
15017 | Supervenience is a modal connection [Sider] |
15008 | Is fundamentality in whole propositions (and holistic), or in concepts (and atomic)? [Sider] |
15013 | Tables and chairs have fundamental existence, but not fundamental natures [Sider] |
15014 | Unlike things, stuff obeys unrestricted composition and mereological essentialism [Sider] |
15009 | We must distinguish 'concrete' from 'abstract' and necessary states of affairs. [Sider] |
13692 | A 'precisification' of a trivalent interpretation reduces it to a bivalent interpretation [Sider] |
13695 | Supervaluational logic is classical, except when it adds the 'Definitely' operator [Sider] |
13693 | A 'supervaluation' assigns further Ts and Fs, if they have been assigned in every precisification [Sider] |
13694 | We can 'sharpen' vague terms, and then define truth as true-on-all-sharpenings [Sider] |
14983 | Accept the ontology of your best theory - and also that it carves nature at the joints [Sider] |
13683 | A relation is a feature of multiple objects taken together [Sider] |
14978 | A property is intrinsic if an object alone in the world can instantiate it [Sider] |
14194 | Proper ontology should only use categorical (actual) properties, not hypothetical ones [Sider] |
14995 | Predicates can be 'sparse' if there is a universal, or if there is a natural property or relation [Sider] |
17011 | I suspect that each particle of bodies has attractive or repelling forces [Newton] |
14745 | If sortal terms fix the kind and the persistence conditions, we need to know what kinds there are [Sider] |
17028 | Particles mutually attract, and cohere at short distances [Newton] |
14740 | If Tib is all of Tibbles bar her tail, when Tibbles loses her tail, two different things become one [Sider] |
14752 | Artists 'create' statues because they are essentially statues, and so lack identity with the lump of clay [Sider] |
14743 | The stage view of objects is best for dealing with coincident entities [Sider] |
14747 | 'Composition as identity' says that an object just is the objects which compose it [Sider] |
17014 | The place of a thing is the sum of the places of its parts [Newton] |
14757 | Mereological essentialism says an object's parts are necessary for its existence [Sider] |
15026 | Essence (even if nonmodal) is not fundamental in metaphysics [Sider] |
14727 | Three-dimensionalists assert 'enduring', being wholly present at each moment, and deny 'temporal parts' [Sider] |
14738 | Some might say that its inconsistency with time travel is a reason to favour three-dimensionalism [Sider] |
14726 | Four-dimensionalists assert 'temporal parts', 'perduring', and being spread out over time [Sider] |
14728 | 4D says intrinsic change is difference between successive parts [Sider] |
14729 | 4D says each spatiotemporal object must have a temporal part at every moment at which it exists [Sider] |
14730 | Temporal parts exist, but are not prior building blocks for objects [Sider] |
14731 | Temporal parts are instantaneous [Sider] |
14758 | How can an instantaneous stage believe anything, if beliefs take time? [Sider] |
14762 | Four-dimensionalism says temporal parts are caused (through laws of motion) by previous temporal parts [Sider] |
14741 | The ship undergoes 'asymmetric' fission, where one candidate is seen as stronger [Sider] |
13702 | The identity of indiscernibles is necessarily true, if being a member of some set counts as a property [Sider] |
14754 | If you say Leibniz's Law doesn't apply to 'timebound' properties, you are no longer discussing identity [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] |
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] |
15030 | Humeans say that we decide what is necessary [Sider] |
15031 | Modal terms in English are entirely contextual, with no modality outside the language [Sider] |
15027 | If truths are necessary 'by convention', that seems to make them contingent [Sider] |
15028 | Conventionalism doesn't seem to apply to examples of the necessary a posteriori [Sider] |
15033 | Humeans says mathematics and logic are necessary because that is how our concept of necessity works [Sider] |
15025 | The world does not contain necessity and possibility - merely how things are [Sider] |
13717 | Transworld identity is not a problem in de dicto sentences, which needn't identify an individual [Sider] |
14763 | Counterparts rest on similarity, so there are many such relations in different contexts [Sider] |
13719 | Barcan Formula problem: there might have been a ghost, despite nothing existing which could be a ghost [Sider] |
14988 | A theory which doesn't fit nature is unexplanatory, even if it is true [Sider] |
17546 | If you changed one of Newton's concepts you would destroy his whole system [Heisenberg on Newton] |
14982 | If I used Ramsey sentences to eliminate fundamentality from my theory, that would be a real loss [Sider] |
17027 | Science deduces propositions from phenomena, and generalises them by induction [Newton] |
14989 | Problem predicates in induction don't reflect the structure of nature [Sider] |
14997 | Two applications of 'grue' do not guarantee a similarity between two things [Sider] |
14990 | Bayes produces weird results if the prior probabilities are bizarre [Sider] |
15005 | Explanations must cite generalisations [Sider] |
17022 | We should admit only enough causes to explain a phenomenon, and no more [Newton] |
17021 | Natural effects of the same kind should be assumed to have the same causes [Newton] |
17026 | From the phenomena, I can't deduce the reason for the properties of gravity [Newton] |
15011 | If the ultimate explanation is a list of entities, no laws, patterns or mechanisms can be cited [Sider] |
15018 | Intentionality is too superficial to appear in the catalogue of ultimate physics [Sider] |
14999 | Prior to conventions, not all green things were green? [Sider] |
14998 | Conventions are contingent and analytic truths are necessary, so that isn't their explanation [Sider] |
15016 | Analyticity has lost its traditional role, which relied on truth by convention [Sider] |
6421 | Newton's four fundamentals are: space, time, matter and force [Newton, by Russell] |
22745 | Pherecydes said the first principle and element is earth [Pherecydes, by Sext.Empiricus] |
13470 | Mass is central to matter [Newton, by Hart,WD] |
17020 | An attraction of a body is the sum of the forces of their particles [Newton] |
23012 | Newtonian causation is changes of motion resulting from collisions [Newton, by Baron/Miller] |
15863 | The principles of my treatise are designed to fit with a belief in God [Newton] |
16746 | Principles of things are not hidden features of forms, but the laws by which they were formed [Newton] |
8340 | I do not pretend to know the cause of gravity [Newton] |
17008 | You have discovered that elliptical orbits result just from gravitation and planetary movement [Newton, by Leibniz] |
17010 | We have given up substantial forms, and now aim for mathematical laws [Newton] |
17023 | I am not saying gravity is essential to bodies [Newton] |
17009 | I won't object if someone shows that gravity consistently arises from the action of matter [Newton] |
13150 | The motions of the planets could only derive from an intelligent agent [Newton] |
12178 | That gravity should be innate and essential to matter is absurd [Newton] |
14985 | The notion of law doesn't seem to enhance physical theories [Sider] |
14987 | Many of the key theories of modern physics do not appear to be 'laws' [Sider] |
15866 | Newton reclassified vertical motion as violent, and unconstrained horizontal motion as natural [Newton, by Harré] |
14725 | Maybe motion is a dynamical quantity intrinsic to a thing at a particular time [Sider] |
15958 | Inertia rejects the Aristotelian idea of things having natural states, to which they return [Newton, by Alexander,P] |
17017 | 1: Bodies rest, or move in straight lines, unless acted on by forces [Newton] |
17018 | 2: Change of motion is proportional to the force [Newton] |
17019 | 3: All actions of bodies have an equal and opposite reaction [Newton] |
20968 | Newton's Third Law implies the conservation of momentum [Newton, by Papineau] |
17547 | Newton's idea of force acting over a long distance was very strange [Heisenberg on Newton] |
20966 | Newton introduced forces other than by contact [Newton, by Papineau] |
20967 | Newton's laws cover the effects of forces, but not their causes [Newton, by Papineau] |
16708 | Newton's forces were accused of being the scholastics' real qualities [Pasnau on Newton] |
13153 | I am studying the quantities and mathematics of forces, not their species or qualities [Newton] |
12724 | The aim is to discover forces from motions, and use forces to demonstrate other phenomena [Newton] |
13593 | Newton showed that falling to earth and orbiting the sun are essentially the same [Newton, by Ellis] |
20969 | Early Newtonians could not formulate conservation of energy, having no concept of potential energy [Newton, by Papineau] |
17013 | Absolute space is independent, homogeneous and immovable [Newton] |
14991 | Space has real betweenness and congruence structure (though it is not the Euclidean concepts) [Sider] |
14735 | Space is 3D and lacks a direction; time seems connected to causation [Sider] |
15021 | The central question in the philosophy of time is: How alike are time and space? [Sider] |
22915 | Newton needs intervals of time, to define velocity and acceleration [Newton, by Le Poidevin] |
22893 | Newton thought his laws of motion needed absolute time [Newton, by Bardon] |
17012 | Time exists independently, and flows uniformly [Newton] |
14012 | Absolute time, from its own nature, flows equably, without relation to anything external [Newton] |
15024 | The spotlight theorists accepts eternal time, but with a spotlight of the present moving across it [Sider] |
14722 | Between presentism and eternalism is the 'growing block' view - the past is real, the future is not [Sider] |
14756 | For Presentists there must always be a temporal vantage point for any description [Sider] |
14724 | Presentists must deny truths about multiple times [Sider] |
14723 | Talk using tenses can be eliminated, by reducing it to indexical connections for an utterance [Sider] |
14736 | The B-theory is adequate, except that it omits to say which time is present [Sider] |
14734 | The B-series involves eternalism, and the reduction of tense [Sider] |
22954 | Newtonian mechanics does not distinguish negative from positive values of time [Newton, by Coveney/Highfield] |
17015 | If there is no uniform motion, we cannot exactly measure time [Newton] |
17025 | If a perfect being does not rule the cosmos, it is not God [Newton] |
17024 | The elegance of the solar system requires a powerful intellect as designer [Newton] |
5883 | Pherecydes was the first to say that the soul is eternal [Pherecydes, by Cicero] |