94 ideas
2797 | As coherence expands its interrelations become steadily tighter, culminating only in necessary truth [Dancy,J] |
8721 | An 'impredicative' definition seems circular, because it uses the term being defined [Friend] |
8680 | Classical definitions attempt to refer, but intuitionist/constructivist definitions actually create objects [Friend] |
3678 | Reductio ad absurdum proves an idea by showing that its denial produces contradiction [Friend] |
8705 | Anti-realists see truth as our servant, and epistemically contrained [Friend] |
2768 | The correspondence theory also has the problem that two sets of propositions might fit the facts equally well [Dancy,J] |
2765 | Rescher says that if coherence requires mutual entailment, this leads to massive logical redundancy [Dancy,J] |
2769 | If one theory is held to be true, all the other theories appear false, because they can't be added to the true one [Dancy,J] |
2766 | Even with a tight account of coherence, there is always the possibility of more than one set of coherent propositions [Dancy,J] |
8713 | In classical/realist logic the connectives are defined by truth-tables [Friend] |
8708 | Double negation elimination is not valid in intuitionist logic [Friend] |
8694 | Free logic was developed for fictional or non-existent objects [Friend] |
8665 | A 'proper subset' of A contains only members of A, but not all of them [Friend] |
8672 | A 'powerset' is all the subsets of a set [Friend] |
8677 | Set theory makes a minimum ontological claim, that the empty set exists [Friend] |
8666 | Infinite sets correspond one-to-one with a subset [Friend] |
8682 | Major set theories differ in their axioms, and also over the additional axioms of choice and infinity [Friend] |
8709 | The law of excluded middle is syntactic; it just says A or not-A, not whether they are true or false [Friend] |
8711 | Intuitionists read the universal quantifier as "we have a procedure for checking every..." [Friend] |
8675 | Paradoxes can be solved by talking more loosely of 'classes' instead of 'sets' [Friend] |
8674 | The Burali-Forti paradox asks whether the set of all ordinals is itself an ordinal [Friend] |
8667 | The 'integers' are the positive and negative natural numbers, plus zero [Friend] |
8668 | The 'rational' numbers are those representable as fractions [Friend] |
8670 | A number is 'irrational' if it cannot be represented as a fraction [Friend] |
8661 | The natural numbers are primitive, and the ordinals are up one level of abstraction [Friend] |
8664 | Cardinal numbers answer 'how many?', with the order being irrelevant [Friend] |
8671 | The 'real' numbers (rationals and irrationals combined) is the Continuum, which has no gaps [Friend] |
8663 | Raising omega to successive powers of omega reveal an infinity of infinities [Friend] |
8662 | The first limit ordinal is omega (greater, but without predecessor), and the second is twice-omega [Friend] |
8669 | Between any two rational numbers there is an infinite number of rational numbers [Friend] |
8676 | Is mathematics based on sets, types, categories, models or topology? [Friend] |
8678 | Most mathematical theories can be translated into the language of set theory [Friend] |
8701 | The number 8 in isolation from the other numbers is of no interest [Friend] |
8702 | In structuralism the number 8 is not quite the same in different structures, only equivalent [Friend] |
8699 | Are structures 'ante rem' (before reality), or are they 'in re' (grounded in physics)? [Friend] |
8696 | Structuralist says maths concerns concepts about base objects, not base objects themselves [Friend] |
8695 | Structuralism focuses on relations, predicates and functions, with objects being inessential [Friend] |
8700 | 'In re' structuralism says that the process of abstraction is pattern-spotting [Friend] |
8681 | The big problem for platonists is epistemic: how do we perceive, intuit, know or detect mathematical facts? [Friend] |
8712 | Mathematics should be treated as true whenever it is indispensable to our best physical theory [Friend] |
8716 | Formalism is unconstrained, so cannot indicate importance, or directions for research [Friend] |
8706 | Constructivism rejects too much mathematics [Friend] |
8707 | Intuitionists typically retain bivalence but reject the law of excluded middle [Friend] |
2781 | Realism says that most perceived objects exist, and have some of their perceived properties [Dancy,J] |
8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
2745 | A pupil who lacks confidence may clearly know something but not be certain of it [Dancy,J] |
2755 | If senses are fallible, then being open to correction is an epistemological virtue [Dancy,J] |
5677 | Naïve direct realists hold that objects retain all of their properties when unperceived [Dancy,J] |
5678 | Scientific direct realism says we know some properties of objects directly [Dancy,J] |
5681 | Maybe we are forced from direct into indirect realism by the need to explain perceptual error [Dancy,J] |
5682 | Internal realism holds that we perceive physical objects via mental objects [Dancy,J] |
5683 | Indirect realism depends on introspection, the time-lag, illusions, and neuroscience [Dancy,J, by PG] |
2778 | Phenomenalism includes possible experiences, but idealism only refers to actual experiences [Dancy,J] |
5684 | Eliminative idealists say there are no objects; reductive idealists say objects exist as complex experiences [Dancy,J] |
2777 | Extreme solipsism only concerns current experience, but it might include past and future [Dancy,J] |
2794 | Knowing that a cow is not a horse seems to be a synthetic a priori truth [Dancy,J] |
2780 | Perception is either direct realism, indirect realism, or phenomenalism [Dancy,J] |
5679 | We can't grasp the separation of quality types, or what a primary-quality world would be like [Dancy,J] |
5680 | For direct realists the secondary and primary qualities seem equally direct [Dancy,J] |
2782 | We can be looking at distant stars which no longer actually exist [Dancy,J] |
2775 | It is not clear from the nature of sense data whether we should accept them as facts [Dancy,J] |
2784 | Appearances don't guarantee reality, unless the appearance is actually caused by the reality [Dancy,J] |
2785 | Perceptual beliefs may be directly caused, but generalisations can't be [Dancy,J] |
2788 | If perception and memory are indirect, then two things stand between mind and reality [Dancy,J] |
2787 | Memories aren't directly about the past, because time-lags and illusions suggest representation [Dancy,J] |
2791 | Phenomenalism about memory denies the past, or reduces it to present experience [Dancy,J] |
2790 | I can remember plans about the future, and images aren't essential (2+3=5) [Dancy,J] |
2754 | Foundations are justified by non-beliefs, or circularly, or they need no justification [Dancy,J] |
2749 | For internalists we must actually know that the fact caused the belief [Dancy,J] |
2770 | Internalists tend to favour coherent justification, but not the coherence theory of truth [Dancy,J] |
2752 | Foundationalism requires inferential and non-inferential justification [Dancy,J] |
2771 | Foundationalists must accept not only the basic beliefs, but also rules of inference for further progress [Dancy,J] |
2756 | If basic beliefs can be false, falsehood in non-basic beliefs might by a symptom [Dancy,J] |
2753 | Beliefs can only be infallible by having almost no content [Dancy,J] |
2773 | Coherentism gives a possible justification of induction, and opposes scepticism [Dancy,J] |
2779 | Idealists must be coherentists, but coherentists needn't be idealists [Dancy,J] |
2786 | For coherentists justification and truth are not radically different things [Dancy,J] |
2767 | If it is empirical propositions which have to be coherent, this eliminates coherent fiction [Dancy,J] |
2776 | Externalism could even make belief unnecessary (e.g. in animals) [Dancy,J] |
2746 | How can a causal theory of justification show that all men die? [Dancy,J] |
2747 | Causal theories don't allow for errors in justification [Dancy,J] |
2772 | Coherentism moves us towards a more social, shared view of knowledge [Dancy,J] |
2743 | What is the point of arguing against knowledge, if being right undermines your own argument? [Dancy,J] |
2751 | Probabilities can only be assessed relative to some evidence [Dancy,J] |
2757 | The argument from analogy rests on one instance alone [Dancy,J] |
2758 | You can't separate mind and behaviour, as the analogy argument attempts [Dancy,J] |
8685 | Studying biology presumes the laws of chemistry, and it could never contradict them [Friend] |
8688 | Concepts can be presented extensionally (as objects) or intensionally (as a characterization) [Friend] |
2744 | Verificationism (the 'verification principle') is an earlier form of anti-realism [Dancy,J] |
2760 | Logical positivism implies foundationalism, by dividing weak from strong verifications [Dancy,J] |
2761 | If the meanings of sentences depend on other sentences, how did we learn language? [Dancy,J] |
2763 | There is an indeterminacy in juggling apparent meanings against probable beliefs [Dancy,J] |
2762 | Charity makes native beliefs largely true, and Humanity makes them similar to ours [Dancy,J] |
5064 | Rights are moral significance, or liberty, or right not to be restrained, or entitlement [Mawson] |