11 ideas
| 21566 | 'Propositional functions' are ambiguous until the variable is given a value [Russell] |
| Full Idea: By a 'propositional function' I mean something which contains a variable x, and expresses a proposition as soon as a value is assigned to x. That is to say, it differs from a proposition solely by the fact that it is ambiguous. | |
| From: Bertrand Russell (The Theory of Logical Types [1910], p.216) | |
| A reaction: This is Frege's notion of a 'concept', as an assertion of a predicate which still lacks a subject. |
| 21567 | 'All judgements made by Epimenedes are true' needs the judgements to be of the same type [Russell] |
| Full Idea: Such a proposition as 'all the judgements made by Epimenedes are true' will only be prima facie capable of truth if all his judgements are of the same order. | |
| From: Bertrand Russell (The Theory of Logical Types [1910], p.227) | |
| A reaction: This is an attempt to use his theory of types to solve the Liar. Tarski's invocation of a meta-language is clearly in the same territory. |
| 23457 | Type theory cannot identify features across levels (because such predicates break the rules) [Morris,M on Russell] |
| Full Idea: Russell's theory of types meant that features common to different levels of the hierarchy became uncapturable (since any attempt to capture them would involve a predicate which disobeyed the hierarchy restrictions). | |
| From: comment on Bertrand Russell (The Theory of Logical Types [1910]) by Michael Morris - Guidebook to Wittgenstein's Tractatus 2H | |
| A reaction: I'm not clear whether this is the main reason why type theory was abandoned. Ramsey was an important critic. |
| 21556 | Classes are defined by propositional functions, and functions are typed, with an axiom of reducibility [Russell, by Lackey] |
| Full Idea: In Russell's mature 1910 theory of types classes are defined in terms of propositional functions, and functions themselves are regimented by a ramified theory of types mitigated by the axiom of reducibility. | |
| From: report of Bertrand Russell (The Theory of Logical Types [1910]) by Douglas Lackey - Intros to Russell's 'Essays in Analysis' p.133 |
| 21568 | A one-variable function is only 'predicative' if it is one order above its arguments [Russell] |
| Full Idea: We will define a function of one variable as 'predicative' when it is of the next order above that of its arguments, i.e. of the lowest order compatible with its having an argument. | |
| From: Bertrand Russell (The Theory of Logical Types [1910], p.237) | |
| A reaction: 'Predicative' just means it produces a set. This is Russell's strict restriction on which functions are predicative. |
| 20034 | Intentions must be mutually consistent, affirm appropriate means, and fit the agent's beliefs [Bratman, by Wilson/Schpall] |
| Full Idea: Bratman's three main norms of intention are 'internal consistency' (between a person's intentions), 'means-end coherence' (the means must fit the end), and 'consistency with the agent's beliefs' (especially intending to do and believing you won't do). | |
| From: report of Michael Bratman (Intention, Plans, and Practical Reason [1987]) by Wilson,G/Schpall,S - Action 4 | |
| A reaction: These are controversial, but have set the agenda for modern non-reductive discussions of intention. |
| 20033 | Intentions are normative, requiring commitment and further plans [Bratman, by Wilson/Schpall] |
| Full Idea: Intentions involve normative commitments. We settle on intended courses, if there is no reason to reconsider them, and intentions put pressure on us to form further intentions in order to more efficiently coordinate our actions. | |
| From: report of Michael Bratman (Intention, Plans, and Practical Reason [1987]) by Wilson,G/Schpall,S - Action 4 | |
| A reaction: [a compression of their summary] This distinguishes them from beliefs and desires, which contain no such normative requirements, even though they may point that way. |
| 20026 | Intention is either the aim of an action, or a long-term constraint on what we can do [Bratman, by Wilson/Schpall] |
| Full Idea: We need to distinguish intention as an aim or goal of actions, and intentions as a distinctive state of commitment to future action, a state that results from and subsequently constrains our practical endeavours as planning agents. | |
| From: report of Michael Bratman (Intention, Plans, and Practical Reason [1987]) by Wilson,G/Schpall,S - Action 2 | |
| A reaction: I'm not sure how distinct these are, given the obvious possibility of intermediate stages, and the embracing of any available short-cut. If I could mow my lawn with one blink, I'd do it. |
| 20032 | Bratman rejected reducing intentions to belief-desire, because they motivate, and have their own standards [Bratman, by Wilson/Schpall] |
| Full Idea: Bratman motivated the idea that intentions are psychologically real and not reducible to desire-belief complexes by observing that they are motivationally distinctive, and subject to their own unique standards of rational appraisal. | |
| From: report of Michael Bratman (Intention, Plans, and Practical Reason [1987]) by Wilson,G/Schpall,S - Action 4 | |
| A reaction: If I thought my belief was a bit warped, and my desire morally corrupt, my higher self might refuse to form an intention. If so, then Bratman is onto something. But maybe my higher self has its own beliefs and desires. |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |