13 ideas
| 11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
| Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
| A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
| 12766 | Logical space is abstracted from the actual world [Stalnaker] |
| Full Idea: Logical space is not given independently of the individuals that occupy it, but is abstracted from the world as we find it. | |
| From: Robert C. Stalnaker (Anti-essentialism [1979], p.85) | |
| A reaction: I very much like the second half of this idea, and am delighted to find Stalnaker endorsing it. I take the logical connectives to be descriptions of how things behave, at a high level of generality. |
| 11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
| Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
| A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
| 11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
| Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
| From: Ian Rumfitt ("Yes" and "No" [2000]) | |
| A reaction: This is the standard view which Rumfitt sets out to challenge. |
| 9935 | Mathematical truth is always compromising between ordinary language and sensible epistemology [Benacerraf] |
| Full Idea: Most accounts of the concept of mathematical truth can be identified with serving one or another of either semantic theory (matching it to ordinary language), or with epistemology (meshing with a reasonable view) - always at the expense of the other. | |
| From: Paul Benacerraf (Mathematical Truth [1973], Intro) | |
| A reaction: The gist is that language pulls you towards platonism, and epistemology pulls you towards empiricism. He argues that the semantics must give ground. He's right. |
| 17927 | Realists have semantics without epistemology, anti-realists epistemology but bad semantics [Benacerraf, by Colyvan] |
| Full Idea: Benacerraf argues that realists about mathematical objects have a nice normal semantic but no epistemology, and anti-realists have a good epistemology but an unorthodox semantics. | |
| From: report of Paul Benacerraf (Mathematical Truth [1973]) by Mark Colyvan - Introduction to the Philosophy of Mathematics 1.2 |
| 9936 | The platonist view of mathematics doesn't fit our epistemology very well [Benacerraf] |
| Full Idea: The principle defect of the standard (platonist) account of mathematical truth is that it appears to violate the requirement that our account be susceptible to integration into our over-all account of knowledge. | |
| From: Paul Benacerraf (Mathematical Truth [1973], III) | |
| A reaction: Unfortunately he goes on to defend a causal theory of justification (fashionable at that time, but implausible now). Nevertheless, his general point is well made. Your theory of what mathematics is had better make it knowable. |
| 12764 | For the bare particular view, properties must be features, not just groups of objects [Stalnaker] |
| Full Idea: If we are to make sense of the bare particular theory, a property must be not just a rule for grouping individuals, but a feature of individuals in virtue of which they may be grouped. | |
| From: Robert C. Stalnaker (Anti-essentialism [1979], p.76) | |
| A reaction: He is offering an objection to the thoroughly extensional account of properties that is found in standard possible worlds semantics. Quite right too. We can't give up on the common sense notion of a property. |
| 12761 | An essential property is one had in all the possible worlds where a thing exists [Stalnaker] |
| Full Idea: If necessity is explained in terms of possible worlds, ...then an essential property is a property that a thing has in all possible worlds in which it exists. | |
| From: Robert C. Stalnaker (Anti-essentialism [1979], p.71) | |
| A reaction: This seems to me to be a quite shocking confusion of necessary properties with essential properties. The point is that utterly trivial properties can be necessary, but in no way part of the real essence of something. |
| 12763 | Necessarily self-identical, or being what it is, or its world-indexed properties, aren't essential [Stalnaker] |
| Full Idea: We can remain anti-essentialist while allowing some necessary properties: those essential to everything (self-identity), relational properties (being what it is), and world-indexed properties (being snub-nosed-only-in-Kronos). | |
| From: Robert C. Stalnaker (Anti-essentialism [1979], p.73) | |
| A reaction: [a summary] He defined essential properties as necessary properties (Idea 12761), and now backpeddles. World-indexed properties are an invention of Plantinga, as essential properties to don't limit individuals. But they are necessary, not essential! |
| 12762 | Bare particular anti-essentialism makes no sense within modal logic semantics [Stalnaker] |
| Full Idea: I argue that one cannot make semantical sense out of bare particular anti-essentialism within the framework of standard semantics for modal logic. | |
| From: Robert C. Stalnaker (Anti-essentialism [1979], p.71) | |
| A reaction: Stalnaker characterises the bare particular view as ANTI-essentialist, because he has defined essence in terms of necessary properties. The bare particular seems to allow the possibility of Aristotle being a poached egg. |
| 12765 | Why imagine that Babe Ruth might be a billiard ball; nothing useful could be said about the ball [Stalnaker] |
| Full Idea: I cannot think of any point in making the counterfactual supposition that Babe Ruth is a billiard ball; there is nothing I can say about him in that imagined state that I could not just as well say about billiard balls that are not him. | |
| From: Robert C. Stalnaker (Anti-essentialism [1979], p.79) | |
| A reaction: A bizarrely circumspect semanticists way of saying that Ruth couldn't possibly be a billiard ball! Would he say the same about a group of old men in wheelchairs, one of whom IS Babe Ruth? |
| 11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
| Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
| A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |