6 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. |
| 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. |
| 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. |
| 7946 | The memory criterion has a problem when one thing branches into two things [Williams,B, by Macdonald,C] |
| Full Idea: The memory criterion for personal identity permits 'branching' (where two things can later meet the criteria of persistence of a single earlier thing), which presents it with serious problems. | |
| From: report of Bernard Williams (Personal Identity and Individuation [1956]) by Cynthia Macdonald - Varieties of Things Ch.4 | |
| A reaction: Of course, any notion of personal identity would have serious problem if people could branch into two, like fissioning amoeba. If that happened, we probably wouldn't have had a strong notion of personal identity in the first place. See Parfit. |
| 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). |
| 8478 | Dewey argued long before Wittgenstein that there could not seriously be a private language [Dewey, by Orenstein] |
| Full Idea: Dewey argued in the twenties that there could not be, in any serious sense, a private language. Wittgenstein also, years later, came to appreciate this point. | |
| From: report of John Dewey (works [1926]) by Alex Orenstein - W.V. Quine Ch.6 | |
| A reaction: A nice historical footnote to perhaps the most famous argument in twentieth century philosophy. Can anyone send me the Dewey reference? |