242 ideas
| 19250 | Everything interesting should be recorded, with records that can be rearranged [Peirce] |
| 9218 | Maybe what distinguishes philosophy from science is its pursuit of necessary truths [Sider] |
| 19228 | Sciences concern existence, but philosophy also concerns potential existence [Peirce] |
| 19241 | An idea on its own isn't an idea, because they are continuous systems [Peirce] |
| 19227 | Philosophy is a search for real truth [Peirce] |
| 19218 | Metaphysics is pointless without exact modern logic [Peirce] |
| 15010 | Your metaphysics is 'cheating' if your ontology won't support the beliefs you accept [Sider] |
| 14721 | Metaphysical enquiry can survive if its conclusions are tentative [Sider] |
| 21489 | Super-ordinate disciplines give laws or principles; subordinate disciplines give concrete cases [Peirce, by Atkin] |
| 6947 | Metaphysics does not rest on facts, but on what we are inclined to believe [Peirce] |
| 14799 | Metaphysics rests on observations, but ones so common we hardly notice them [Peirce] |
| 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] |
| 19229 | Metaphysics is the science of both experience, and its general laws and types [Peirce] |
| 15003 | It seems unlikely that the way we speak will give insights into the universe [Sider] |
| 19219 | Metaphysical reasoning is simple enough, but the concepts are very hard [Peirce] |
| 14767 | The demonstrations of the metaphysicians are all moonshine [Peirce] |
| 14986 | Conceptual analysts trust particular intuitions much more than general ones [Sider] |
| 19231 | Metaphysics is turning into logic, and logic is becoming mathematics [Peirce] |
| 14764 | I am saturated with the spirit of physical science [Peirce] |
| 14782 | Philosophy is an experimental science, resting on common experience [Peirce] |
| 6937 | Reason aims to discover the unknown by thinking about the known [Peirce] |
| 14779 | I reason in order to avoid disappointment and surprise [Peirce] |
| 14787 | Self-contradiction doesn't reveal impossibility; it is inductive impossibility which reveals self-contradiction [Peirce] |
| 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] |
| 19247 | The one unpardonable offence in reasoning is to block the route to further truth [Peirce] |
| 15012 | Orthodox truthmaker theories make entities fundamental, but that is poor for explanation [Sider] |
| 7661 | Truth is the opinion fated to be ultimately agreed by all investigators [Peirce] |
| 19095 | Pragmatic 'truth' is a term to cover the many varied aims of enquiry [Peirce, by Misak] |
| 19097 | Peirce did not think a belief was true if it was useful [Peirce, by Misak] |
| 21494 | If truth is the end of enquiry, what if it never ends, or ends prematurely? [Atkin on Peirce] |
| 19246 | 'Holding for true' is either practical commitment, or provisional theory [Peirce] |
| 15335 | Peirce's theory offers anti-realist verificationism, but surely how things are is independent of us? [Horsten on Peirce] |
| 14796 | Independent truth (if there is any) is the ultimate result of sufficient enquiry [Peirce] |
| 14777 | That a judgement is true and that we judge it true are quite different things [Peirce] |
| 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] |
| 14780 | Only study logic if you think your own reasoning is deficient [Peirce] |
| 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] |
| 19237 | Deduction is true when the premises facts necessarily make the conclusion fact true [Peirce] |
| 19256 | Our research always hopes that reality embodies the logic we are employing [Peirce] |
| 21493 | Pure mathematics deals only with hypotheses, of which the reality does not matter [Peirce] |
| 14783 | Logic, unlike mathematics, is not hypothetical; it asserts categorical ends from hypothetical means [Peirce] |
| 19102 | Bivalence is a regulative assumption of enquiry - not a law of logic [Peirce, by Misak] |
| 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] |
| 19238 | The logic of relatives relies on objects built of any relations (rather than on classes) [Peirce] |
| 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] |
| 14775 | Numbers are just names devised for counting [Peirce] |
| 13701 | A single second-order sentence validates all of arithmetic - but this can't be proved axiomatically [Sider] |
| 14776 | That two two-eyed people must have four eyes is a statement about numbers, not a fact [Peirce] |
| 14788 | Mathematics is close to logic, but is even more abstract [Peirce] |
| 19226 | We now know that mathematics only studies hypotheses, not facts [Peirce] |
| 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] |
| 21492 | Realism is basic to the scientific method [Peirce] |
| 19240 | Realism is the belief that there is something in the being of things corresponding to our reasoning [Peirce] |
| 19239 | There may be no reality; it's just our one desperate hope of knowing anything [Peirce] |
| 10352 | The real is the idea in which the community ultimately settles down [Peirce] |
| 6949 | If someone doubted reality, they would not actually feel dissatisfaction [Peirce] |
| 14778 | Facts are hard unmoved things, unaffected by what people may think of them [Peirce] |
| 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] |
| 13498 | Peirce and others began the mapping out of relations [Peirce, by Hart,WD] |
| 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] |
| 21491 | Peirce's later realism about possibilities and generalities went beyond logical positivism [Peirce, by Atkin] |
| 14745 | If sortal terms fix the kind and the persistence conditions, we need to know what kinds there are [Sider] |
| 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] |
| 14798 | All communication is vague, and is outside the principle of non-contradiction [Peirce] |
| 14797 | Vagueness is a neglected but important part of mathematical thought [Peirce] |
| 14747 | 'Composition as identity' says that an object just is the objects which compose it [Sider] |
| 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] |
| 14786 | Some logical possibility concerns single propositions, but there is also compatibility between propositions [Peirce] |
| 14804 | Is chance just unknown laws? But the laws operate the same, whatever chance occurs [Peirce] |
| 19252 | Objective chance is the property of a distribution [Peirce] |
| 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] |
| 14303 | Truth-functional conditionals have a simple falsification, when A is true and B is false [Peirce] |
| 19232 | In ordinary language a conditional statement assumes that the antecedent is true [Peirce] |
| 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] |
| 16376 | The possible can only be general, and the force of actuality is needed to produce a particular [Peirce] |
| 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] |
| 19089 | Our whole conception of an object is its possible practical consequences [Peirce] |
| 7660 | We are aware of beliefs, they appease our doubts, and they are rules of action, or habits [Peirce] |
| 6940 | The feeling of belief shows a habit which will determine our actions [Peirce] |
| 6941 | We are entirely satisfied with a firm belief, even if it is false [Peirce] |
| 6942 | We want true beliefs, but obviously we think our beliefs are true [Peirce] |
| 6943 | A mere question does not stimulate a struggle for belief; there must be a real doubt [Peirce] |
| 14781 | A 'belief' is a habit which determines how our imagination and actions proceed [Peirce] |
| 19223 | We act on 'full belief' in a crisis, but 'opinion' only operates for trivial actions [Peirce] |
| 19107 | Inquiry is not standing on bedrock facts, but standing in hope on a shifting bog [Peirce] |
| 14770 | Reasoning is based on statistical induction, so it can't achieve certainty or precision [Peirce] |
| 14768 | Infallibility in science is just a joke [Peirce] |
| 14774 | Innate truths are very uncertain and full of error, so they certainly have exceptions [Peirce] |
| 14789 | Experience is indeed our only source of knowledge, provided we include inner experience [Peirce] |
| 19253 | We talk of 'association by resemblance' but that is wrong: the association constitutes the resemblance [Peirce] |
| 14765 | Association of ideas is the best philosophical idea of the prescientific age [Peirce] |
| 14794 | Instead of seeking Truth, we should seek belief that is beyond doubt [Peirce] |
| 14795 | Pragmatism is a way of establishing meanings, not a theory of metaphysics or a set of truths [Peirce] |
| 14785 | The world is one of experience, but experiences are always located among our ideas [Peirce] |
| 14773 | A truth is hard for us to understand if it rests on nothing but inspiration [Peirce] |
| 14772 | If we decide an idea is inspired, we still can't be sure we have got the idea right [Peirce] |
| 14771 | Only reason can establish whether some deliverance of revelation really is inspired [Peirce] |
| 6598 | We need our beliefs to be determined by some external inhuman permanency [Peirce] |
| 19224 | Scientists will give up any conclusion, if experience opposes it [Peirce] |
| 6944 | Demonstration does not rest on first principles of reason or sensation, but on freedom from actual doubt [Peirce] |
| 6948 | Doubts should be satisfied by some external permanency upon which thinking has no effect [Peirce] |
| 6945 | Once doubt ceases, there is no point in continuing to argue [Peirce] |
| 19243 | If each inference slightly reduced our certainty, science would soon be in trouble [Peirce] |
| 14766 | Duns Scotus offers perhaps the best logic and metaphysics for modern physical science [Peirce] |
| 19225 | I classify science by level of abstraction; principles derive from above, and data from below [Peirce] |
| 14988 | A theory which doesn't fit nature is unexplanatory, even if it is true [Sider] |
| 14982 | If I used Ramsey sentences to eliminate fundamentality from my theory, that would be a real loss [Sider] |
| 19234 | 'Induction' doesn't capture Greek 'epagoge', which is singulars in a mass producing the general [Peirce] |
| 19235 | How does induction get started? [Peirce] |
| 19236 | Induction can never prove that laws have no exceptions [Peirce] |
| 19251 | The worst fallacy in induction is generalising one recondite property from a sample [Peirce] |
| 14997 | Two applications of 'grue' do not guarantee a similarity between two things [Sider] |
| 14989 | Problem predicates in induction don't reflect the structure of nature [Sider] |
| 14990 | Bayes produces weird results if the prior probabilities are bizarre [Sider] |
| 15005 | Explanations must cite generalisations [Sider] |
| 14790 | 'Abduction' is beginning a hypothesis, particularly if it includes preference of one explanation over others [Peirce] |
| 14791 | Abduction involves original suggestions, and not just the testing involved in induction [Peirce] |
| 15011 | If the ultimate explanation is a list of entities, no laws, patterns or mechanisms can be cited [Sider] |
| 19222 | Men often answer inner 'whys' by treating unconscious instincts as if they were reasons [Peirce] |
| 19220 | We may think animals reason very little, but they hardly ever make mistakes! [Peirce] |
| 15018 | Intentionality is too superficial to appear in the catalogue of ultimate physics [Sider] |
| 14769 | Only imagination can connect phenomena together in a rational way [Peirce] |
| 19255 | Generalisation is the great law of mind [Peirce] |
| 19242 | Generalization is the true end of life [Peirce] |
| 19249 | 'Know yourself' is not introspection; it is grasping how others see you [Peirce] |
| 14802 | Physical and psychical laws of mind are either independent, or derived in one or other direction [Peirce] |
| 19257 | Whatever is First must be sentient [Peirce] |
| 19248 | Reasoning involves observation, experiment, and habituation [Peirce] |
| 19221 | Everybody overrates their own reasoning, so it is clearly superficial [Peirce] |
| 14792 | A 'conception', the rational implication of a word, lies in its bearing upon the conduct of life [Peirce] |
| 14793 | The definition of a concept is just its experimental implications [Peirce] |
| 19087 | The meaning or purport of a symbol is all the rational conduct it would lead to [Peirce] |
| 14906 | Non-positivist verificationism says only take a hypothesis seriously if it is scientifically based and testable [Ladyman/Ross on Peirce] |
| 14999 | Prior to conventions, not all green things were green? [Sider] |
| 7634 | Icons resemble their subject, an index is a natural sign, and symbols are conventional [Peirce, by Maund] |
| 19233 | Indexicals are unusual words, because they stimulate the hearer to look around [Peirce] |
| 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] |
| 14784 | Ethics is the science of aims [Peirce] |
| 14805 | Is there any such thing as death among the lower organisms? [Peirce] |
| 20239 | Unlike us, the early Greeks thought envy was a good thing, and hope a bad thing [Hesiod, by Nietzsche] |
| 19230 | People should follow what lies before them, and is within their power [Peirce] |
| 19245 | We are not inspired by other people's knowledge; a sense of our ignorance motivates study [Peirce] |
| 19244 | Chemists rely on a single experiment to establish a fact; repetition is pointless [Peirce] |
| 6939 | What is true of one piece of copper is true of another (unlike brass) [Peirce] |
| 14800 | The world is full of variety, but laws seem to produce uniformity [Peirce] |
| 19254 | Our laws of nature may be the result of evolution [Peirce] |
| 14806 | If the world is just mechanical, its whole specification has no more explanation than mere chance [Peirce] |
| 14803 | The more precise the observations, the less reliable appear to be the laws of nature [Peirce] |
| 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] |
| 14725 | Maybe motion is a dynamical quantity intrinsic to a thing at a particular time [Sider] |
| 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] |
| 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] |
| 6938 | Natural selection might well fill an animal's mind with pleasing thoughts rather than true ones [Peirce] |
| 14801 | Darwinian evolution is chance, with the destruction of bad results [Peirce] |
| 6946 | If death is annihilation, belief in heaven is a cheap pleasure with no disappointment [Peirce] |