85 ideas
| 3822 | Theory involves accepting conclusions, and so is a special case of practical reason [Searle] |
| 3811 | Entailment and validity are relations, but inference is a human activity [Searle] |
| 3812 | Rationality is the way we coordinate our intentionality [Searle] |
| 3806 | Rationality is built into the intentionality of the mind, and its means of expression [Searle] |
| 13634 | Satisfaction is 'truth in a model', which is a model of 'truth' [Shapiro] |
| 13643 | Aristotelian logic is complete [Shapiro] |
| 13651 | A set is 'transitive' if contains every member of each of its members [Shapiro] |
| 13647 | Choice is essential for proving downward Löwenheim-Skolem [Shapiro] |
| 13631 | Are sets part of logic, or part of mathematics? [Shapiro] |
| 13654 | It is central to the iterative conception that membership is well-founded, with no infinite descending chains [Shapiro] |
| 13640 | Russell's paradox shows that there are classes which are not iterative sets [Shapiro] |
| 13666 | Iterative sets are not Boolean; the complement of an iterative set is not an iterative sets [Shapiro] |
| 13653 | 'Well-ordering' of a set is an irreflexive, transitive, and binary relation with a least element [Shapiro] |
| 3809 | If complex logic requires rules, then so does basic logic [Searle] |
| 13627 | There is no 'correct' logic for natural languages [Shapiro] |
| 13642 | Logic is the ideal for learning new propositions on the basis of others [Shapiro] |
| 13668 | Bernays (1918) formulated and proved the completeness of propositional logic [Shapiro] |
| 13669 | Can one develop set theory first, then derive numbers, or are numbers more basic? [Shapiro] |
| 13667 | Skolem and Gödel championed first-order, and Zermelo, Hilbert, and Bernays championed higher-order [Shapiro] |
| 13662 | First-order logic was an afterthought in the development of modern logic [Shapiro] |
| 13624 | The 'triumph' of first-order logic may be related to logicism and the Hilbert programme, which failed [Shapiro] |
| 13660 | Maybe compactness, semantic effectiveness, and the Löwenheim-Skolem properties are desirable [Shapiro] |
| 13673 | The notion of finitude is actually built into first-order languages [Shapiro] |
| 15944 | Second-order logic is better than set theory, since it only adds relations and operations, and nothing else [Shapiro, by Lavine] |
| 13629 | Broad standard semantics, or Henkin semantics with a subclass, or many-sorted first-order semantics? [Shapiro] |
| 13650 | Henkin semantics has separate variables ranging over the relations and over the functions [Shapiro] |
| 13645 | In standard semantics for second-order logic, a single domain fixes the ranges for the variables [Shapiro] |
| 13649 | Completeness, Compactness and Löwenheim-Skolem fail in second-order standard semantics [Shapiro] |
| 13626 | Semantic consequence is ineffective in second-order logic [Shapiro] |
| 13637 | If a logic is incomplete, its semantic consequence relation is not effective [Shapiro] |
| 13632 | Finding the logical form of a sentence is difficult, and there are no criteria of correctness [Shapiro] |
| 13674 | We might reduce ontology by using truth of sentences and terms, instead of using objects satisfying models [Shapiro] |
| 3810 | In real reasoning semantics gives validity, not syntax [Searle] |
| 13633 | 'Satisfaction' is a function from models, assignments, and formulas to {true,false} [Shapiro] |
| 13644 | Semantics for models uses set-theory [Shapiro] |
| 13636 | An axiomatization is 'categorical' if its models are isomorphic, so there is really only one interpretation [Shapiro] |
| 13670 | Categoricity can't be reached in a first-order language [Shapiro] |
| 13658 | Downward Löwenheim-Skolem: each satisfiable countable set always has countable models [Shapiro] |
| 13659 | Upward Löwenheim-Skolem: each infinite model has infinite models of all sizes [Shapiro] |
| 13648 | The Löwenheim-Skolem theorems show an explosion of infinite models, so 1st-order is useless for infinity [Shapiro] |
| 13675 | Substitutional semantics only has countably many terms, so Upward Löwenheim-Skolem trivially fails [Shapiro] |
| 13635 | 'Weakly sound' if every theorem is a logical truth; 'sound' if every deduction is a semantic consequence [Shapiro] |
| 13628 | We can live well without completeness in logic [Shapiro] |
| 13630 | Non-compactness is a strength of second-order logic, enabling characterisation of infinite structures [Shapiro] |
| 13646 | Compactness is derived from soundness and completeness [Shapiro] |
| 13661 | A language is 'semantically effective' if its logical truths are recursively enumerable [Shapiro] |
| 13641 | Complex numbers can be defined as reals, which are defined as rationals, then integers, then naturals [Shapiro] |
| 13676 | Only higher-order languages can specify that 0,1,2,... are all the natural numbers that there are [Shapiro] |
| 13677 | Natural numbers are the finite ordinals, and integers are equivalence classes of pairs of finite ordinals [Shapiro] |
| 13652 | The 'continuum' is the cardinality of the powerset of a denumerably infinite set [Shapiro] |
| 13657 | First-order arithmetic can't even represent basic number theory [Shapiro] |
| 13656 | Some sets of natural numbers are definable in set-theory but not in arithmetic [Shapiro] |
| 13664 | Logicism is distinctive in seeking a universal language, and denying that logic is a series of abstractions [Shapiro] |
| 13625 | Mathematics and logic have no border, and logic must involve mathematics and its ontology [Shapiro] |
| 13663 | Some reject formal properties if they are not defined, or defined impredicatively [Shapiro] |
| 3841 | Users of 'supervenience' blur its causal and constitutive meanings [Searle] |
| 13638 | Properties are often seen as intensional; equiangular and equilateral are different, despite identity of objects [Shapiro] |
| 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] |
| 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] |
| 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] |
| 19384 | Space and time are the order of all possibilities, and don't just relate to what is actual [Leibniz] |