89 ideas
| 13466 | We are all post-Kantians, because he set the current agenda for philosophy [Hart,WD] |
| 13477 | The problems are the monuments of philosophy [Hart,WD] |
| 13515 | To study abstract problems, some knowledge of set theory is essential [Hart,WD] |
| 3811 | Entailment and validity are relations, but inference is a human activity [Searle] |
| 3822 | Theory involves accepting conclusions, and so is a special case of practical reason [Searle] |
| 3806 | Rationality is built into the intentionality of the mind, and its means of expression [Searle] |
| 3812 | Rationality is the way we coordinate our intentionality [Searle] |
| 19125 | If we define truth, we can eliminate it [Halbach/Leigh] |
| 13469 | Tarski showed how we could have a correspondence theory of truth, without using 'facts' [Hart,WD] |
| 13504 | Truth for sentences is satisfaction of formulae; for sentences, either all sequences satisfy it (true) or none do [Hart,WD] |
| 19128 | If a language cannot name all objects, then satisfaction must be used, instead of unary truth [Halbach/Leigh] |
| 19120 | Semantic theories need a powerful metalanguage, typically including set theory [Halbach/Leigh] |
| 13503 | A first-order language has an infinity of T-sentences, which cannot add up to a definition of truth [Hart,WD] |
| 19127 | The T-sentences are deductively weak, and also not deductively conservative [Halbach/Leigh] |
| 19124 | A natural theory of truth plays the role of reflection principles, establishing arithmetic's soundness [Halbach/Leigh] |
| 19126 | If deflationary truth is not explanatory, truth axioms should be 'conservative', proving nothing new [Halbach/Leigh] |
| 19129 | The FS axioms use classical logical, but are not fully consistent [Halbach/Leigh] |
| 19130 | KF is formulated in classical logic, but describes non-classical truth, which allows truth-value gluts [Halbach/Leigh] |
| 13500 | Conditional Proof: infer a conditional, if the consequent can be deduced from the antecedent [Hart,WD] |
| 13502 | ∃y... is read as 'There exists an individual, call it y, such that...', and not 'There exists a y such that...' [Hart,WD] |
| 13456 | Set theory articulates the concept of order (through relations) [Hart,WD] |
| 13497 | Nowadays ZFC and NBG are the set theories; types are dead, and NF is only useful for the whole universe [Hart,WD] |
| 13443 | ∈ relates across layers, while ⊆ relates within layers [Hart,WD] |
| 13442 | Without the empty set we could not form a∩b without checking that a and b meet [Hart,WD] |
| 13493 | In the modern view, foundation is the heart of the way to do set theory [Hart,WD] |
| 13495 | Foundation Axiom: an nonempty set has a member disjoint from it [Hart,WD] |
| 13461 | We can choose from finite and evident sets, but not from infinite opaque ones [Hart,WD] |
| 13462 | With the Axiom of Choice every set can be well-ordered [Hart,WD] |
| 13516 | If we accept that V=L, it seems to settle all the open questions of set theory [Hart,WD] |
| 13441 | Naïve set theory has trouble with comprehension, the claim that every predicate has an extension [Hart,WD] |
| 13494 | The iterative conception may not be necessary, and may have fixed points or infinitely descending chains [Hart,WD] |
| 13457 | A 'partial ordering' is irreflexive and transitive; the sets are ordered, but not the subsets [Hart,WD] |
| 13458 | A partial ordering becomes 'total' if any two members of its field are comparable [Hart,WD] |
| 13460 | 'Well-ordering' must have a least member, so it does the natural numbers but not the integers [Hart,WD] |
| 13490 | Von Neumann defines α<β as α∈β [Hart,WD] |
| 13481 | Maybe sets should be rethought in terms of the even more basic categories [Hart,WD] |
| 3809 | If complex logic requires rules, then so does basic logic [Searle] |
| 13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
| 3810 | In real reasoning semantics gives validity, not syntax [Searle] |
| 13512 | Modern model theory begins with the proof of Los's Conjecture in 1962 [Hart,WD] |
| 13505 | Model theory studies how set theory can model sets of sentences [Hart,WD] |
| 13511 | Model theory is mostly confined to first-order theories [Hart,WD] |
| 13513 | Models are ways the world might be from a first-order point of view [Hart,WD] |
| 13496 | First-order logic is 'compact': consequences of a set are consequences of a finite subset [Hart,WD] |
| 13484 | Berry's Paradox: we succeed in referring to a number, with a term which says we can't do that [Hart,WD] |
| 13482 | The Burali-Forti paradox is a crisis for Cantor's ordinals [Hart,WD] |
| 13507 | The machinery used to solve the Liar can be rejigged to produce a new Liar [Hart,WD] |
| 13459 | The less-than relation < well-orders, and partially orders, and totally orders the ordinal numbers [Hart,WD] |
| 13491 | The axiom of infinity with separation gives a least limit ordinal ω [Hart,WD] |
| 13463 | There are at least as many infinite cardinals as transfinite ordinals (because they will map) [Hart,WD] |
| 13492 | Von Neumann's ordinals generalise into the transfinite better, because Zermelo's ω is a singleton [Hart,WD] |
| 13446 | 19th century arithmetization of analysis isolated the real numbers from geometry [Hart,WD] |
| 13509 | We can establish truths about infinite numbers by means of induction [Hart,WD] |
| 13474 | Euclid has a unique parallel, spherical geometry has none, and saddle geometry has several [Hart,WD] |
| 13471 | Mathematics makes existence claims, but philosophers usually say those are never analytic [Hart,WD] |
| 3841 | Users of 'supervenience' blur its causal and constitutive meanings [Searle] |
| 13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
| 19121 | We can reduce properties to true formulas [Halbach/Leigh] |
| 19122 | Nominalists can reduce theories of properties or sets to harmless axiomatic truth theories [Halbach/Leigh] |
| 3816 | Our beliefs are about things, not propositions (which are the content of the belief) [Searle] |
| 3833 | A belief is a commitment to truth [Searle] |
| 3837 | We can't understand something as a lie if beliefs aren't commitment to truth [Searle] |
| 3828 | Thinking must involve a self, not just an "it" [Searle] |
| 13480 | Fregean self-evidence is an intrinsic property of basic truths, rules and definitions [Hart,WD] |
| 13476 | The failure of key assumptions in geometry, mereology and set theory throw doubt on the a priori [Hart,WD] |
| 3831 | Reasons can either be facts in the world, or intentional states [Searle] |
| 3830 | In the past people had a reason not to smoke, but didn't realise it [Searle] |
| 3832 | Causes (usually events) are not the same as reasons (which are never events) [Searle] |
| 3823 | Being held responsible for past actions makes no sense without personal identity [Searle] |
| 3821 | Giving reasons for action requires reference to a self [Searle] |
| 3824 | A 'self' must be capable of conscious reasonings about action [Searle] |
| 3834 | An intentional, acting, rational being must have a self [Searle] |
| 3825 | Action requires a self, even though perception doesn't [Searle] |
| 3829 | Selfs are conscious, enduring, reasonable, active, free, and responsible [Searle] |
| 3826 | A self must at least be capable of consciousness [Searle] |
| 3827 | The self is neither an experience nor a thing experienced [Searle] |
| 3820 | The bundle must also have agency in order to act, and a self to act rationally [Searle] |
| 3817 | Free will is most obvious when we choose between several reasons for an action [Searle] |
| 3808 | Rational decision making presupposes free will [Searle] |
| 3818 | We freely decide whether to make a reason for action effective [Searle] |
| 13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
| 3814 | Preferences can result from deliberation, not just precede it [Searle] |
| 3840 | We don't accept practical reasoning if the conclusion is unpalatable [Searle] |
| 3815 | The essence of humanity is desire-independent reasons for action [Searle] |
| 3839 | Only an internal reason can actually motivate the agent to act [Searle] |
| 3835 | If it is true, you ought to believe it [Searle] |
| 3836 | If this is a man, you ought to accept similar things as men [Searle] |
| 3838 | Promises hold because I give myself a reason, not because it is an institution [Searle] |
| 3813 | 'Ought' implies that there is a reason to do something [Searle] |