14 ideas
| 23367 | Even pointing a finger should only be done for a reason [Epictetus] |
| Full Idea: Philosophy says it is not right even to stretch out a finger without some reason. | |
| From: Epictetus (fragments/reports [c.57], 15) | |
| A reaction: The key point here is that philosophy concerns action, an idea on which Epictetus is very keen. He rather despise theory. This idea perfectly sums up the concept of the wholly rational life (which no rational person would actually want to live!). |
| 18755 | Validity is explained as truth in all models, because that relies on the logical terms [McGee] |
| Full Idea: A model of a language assigns values to non-logical terms. If a sentence is true in every model, its truth doesn't depend on those non-logical terms. Hence the validity of an argument comes from its logical form. Thus models explain logical validity. | |
| From: Vann McGee (Logical Consequence [2014], 4) | |
| A reaction: [compressed] Thus you get a rigorous account of logical validity by only allowing the rigorous input of model theory. This is the modern strategy of analytic philosophy. But is 'it's red so it's coloured' logically valid? |
| 18751 | Natural language includes connectives like 'because' which are not truth-functional [McGee] |
| Full Idea: Natural language includes connectives that are not truth-functional. In order for 'p because q' to be true, both p and q have to be true, but knowing the simpler sentences are true doesn't determine whether the larger sentence is true. | |
| From: Vann McGee (Logical Consequence [2014], 2) |
| 18914 | Davidson controversially proposed to quantify over events [Davidson, by Engelbretsen] |
| Full Idea: An alternative, and still controversial, extension of first-order logic is due to Donald Davidson, who allows for quantification over events. | |
| From: report of Donald Davidson (The Individuation of Events [1969]) by George Engelbretsen - Trees, Terms and Truth 3 | |
| A reaction: I'm suddenly thinking this is quite an attractive proposal. We need to quantify over facts, or states of affairs, or events, or some such thing, to talk about the world properly. Objects, predicates and sets/parts is too sparse. I like facts. |
| 18761 | Second-order variables need to range over more than collections of first-order objects [McGee] |
| Full Idea: To get any advantage from moving to second-order logic, we need to assign to second-order variables a role different from merely ranging over collections made up of things the first-order variables range over. | |
| From: Vann McGee (Logical Consequence [2014], 7) | |
| A reaction: Thus it is exciting if they range over genuine properties, but not so exciting if you merely characterise those properties as sets of first-order objects. This idea leads into a discussion of plural quantification. |
| 18753 | An ontologically secure semantics for predicate calculus relies on sets [McGee] |
| Full Idea: We can get a less ontologically perilous presentation of the semantics of the predicate calculus by using sets instead of concepts. | |
| From: Vann McGee (Logical Consequence [2014], 4) | |
| A reaction: The perilous versions rely on Fregean concepts, and notably Russell's 'concept that does not fall under itself'. The sets, of course, have to be ontologically secure, and so will involve the iterative conception, rather than naive set theory. |
| 18754 | Logically valid sentences are analytic truths which are just true because of their logical words [McGee] |
| Full Idea: Logically valid sentences are a species of analytic sentence, being true not just in virtue of the meanings of their words, but true in virtue of the meanings of their logical words. | |
| From: Vann McGee (Logical Consequence [2014], 4) | |
| A reaction: A helpful link between logical truths and analytic truths, which had not struck me before. |
| 18757 | Soundness theorems are uninformative, because they rely on soundness in their proofs [McGee] |
| Full Idea: Soundness theorems are seldom very informative, since typically we use informally, in proving the theorem, the very same rules whose soundness we are attempting to establish. | |
| From: Vann McGee (Logical Consequence [2014], 5) | |
| A reaction: [He cites Quine 1935] |
| 18760 | The culmination of Euclidean geometry was axioms that made all models isomorphic [McGee] |
| Full Idea: One of the culminating achievements of Euclidean geometry was categorical axiomatisations, that describe the geometric structure so completely that any two models of the axioms are isomorphic. The axioms are second-order. | |
| From: Vann McGee (Logical Consequence [2014], 7) | |
| A reaction: [He cites Veblen 1904 and Hilbert 1903] For most mathematicians, categorical axiomatisation is the best you can ever dream of (rather than a single true axiomatisation). |
| 9843 | You can't identify events by causes and effects, as the event needs to be known first [Dummett on Davidson] |
| Full Idea: Davidson's criterion for the identity of events is a mistake, because we cannot know the causes and effects of an event until we know what that event comprises. | |
| From: comment on Donald Davidson (The Individuation of Events [1969]) by Michael Dummett - Frege philosophy of mathematics Ch.10 | |
| A reaction: How many attempts by analytical philosophers to give necessary and sufficient conditions for things seem to founder in this way. Their predecessor is at the end of 'Theaetetus'; you have to know what the sun is before you can define it. |
| 14602 | Events can only be individuated causally [Davidson, by Schaffer,J] |
| Full Idea: Davidson claims that events can only be individuated causally. | |
| From: report of Donald Davidson (The Individuation of Events [1969], 3) by Jonathan Schaffer - Causation and Laws of Nature 3 | |
| A reaction: Schaffer rejects this in favour of individuating events by their spatiotemporal locations and intrinsic natures (which seem to be property instantiations, a la Kim). Schaffer was a pupil of David Lewis. |
| 14004 | We need events for action statements, causal statements, explanation, mind-and-body, and adverbs [Davidson, by Bourne] |
| Full Idea: Davidson claims that we require the existence of events in order to make sense of a) action statements, b) causal statements, c) explanation, d) the mind-body problem, and e) the logic of adverbial modification. | |
| From: report of Donald Davidson (The Individuation of Events [1969], Intro IIb) by Craig Bourne - A Future for Presentism | |
| A reaction: Events are a nice shorthand, but I don't like them in a serious ontology. Prior says there objects and what happens to them; Kim reduces events to other things. Processes are more clearly individuated than events. |
| 8278 | The claim that events are individuated by their causal relations to other events is circular [Lowe on Davidson] |
| Full Idea: Davidson has urged that events are individuated by the causal relations which they bear to one another, in accordance with the principle that events are identical just in case they have the same causes and effects. But the principle is viciously circular. | |
| From: comment on Donald Davidson (The Individuation of Events [1969]) by E.J. Lowe - The Possibility of Metaphysics 7.4 | |
| A reaction: You wouldn't want to identify a person just by their relationships, even though those will certainly be unique. Generally it is what I am (right now) naming as the Functional Fallacy: believing that specifying the function of x explains x. |
| 18762 | A maxim claims that if we are allowed to assert a sentence, that means it must be true [McGee] |
| Full Idea: If our linguistic conventions entitle us to assert a sentence, they thereby make it true, because of the maxim that 'truth is the norm of assertion'. | |
| From: Vann McGee (Logical Consequence [2014], 8) | |
| A reaction: You could only really deny that maxim if you had no belief at all in truth, but then you can assert anything you like (with full entitlement). Maybe you can assert anything you like as long as it doesn't upset anyone? Etc. |