12 ideas
| 19086 | Does the pragmatic theory of meaning support objective truth, or make it impossible? [Macbeth] |
| Full Idea: Peirce and Sellars takes Peirce's conception of meaning, on which pragmatism is founded, to support an adequate account of objective truth; James, Dewey and Rorty say it forecloses all possibility of such an account. | |
| From: Danielle Macbeth (Pragmatism and Objective Truth [2007], p.169) | |
| A reaction: Ah. Very helpful. I thought there was a pragmatic theory of truth, then began to think that it was just a denial of truth. I've long suspected that Peirce is wonderful, and James is not very good (on this topic). |
| 14970 | Normal system K has five axioms and rules [Cresswell] |
| Full Idea: Normal propositional modal logics derive from the minimal system K: wffs of PC are axioms; □(p⊃q)⊃(□p⊃□q); uniform substitution; modus ponens; necessitation (α→□α). | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1) |
| 14971 | D is valid on every serial frame, but not where there are dead ends [Cresswell] |
| Full Idea: If a frame contains any dead end or blind world, then D is not valid on that frame, ...but D is valid on every serial frame. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.1) |
| 14972 | S4 has 14 modalities, and always reduces to a maximum of three modal operators [Cresswell] |
| Full Idea: In S4 there are exactly 14 distinct modalities, and any modality may be reduced to one containing no more than three modal operators in sequence. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
| A reaction: The significance of this may be unclear, but it illustrates one of the rewards of using formal systems to think about modal problems. There is at least an appearance of precision, even if it is only conditional precision. |
| 14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
| Full Idea: S5 contains the four main reduction laws, so the first of any pair of operators may be deleted. Hence all but the last modal operator may be deleted. This leaves six modalities: p, ◊p, □p, and their negations. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) |
| 14976 | Reject the Barcan if quantifiers are confined to worlds, and different things exist in other worlds [Cresswell] |
| Full Idea: If one wants the quantifiers in each world to range only over the things that exist in that world, and one doesn't believe that the same things exist in every world, one would probably not want the Barcan formula. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.2.2) | |
| A reaction: I haven't quite got this, but it sounds to me like I should reject the Barcan formula (but Idea 9449!). I like a metaphysics to rest on the actual world (with modal properties). I assume different things could have existed, but don't. |
| 19093 | Greek mathematics is wholly sensory, where ours is wholly inferential [Macbeth] |
| Full Idea: Ancient mathematical concepts were essentially sensory; they were not mathematical in our sense - that is, wholly constituted by their inferential potential. | |
| From: Danielle Macbeth (Pragmatism and Objective Truth [2007], p.187) | |
| A reaction: The latter view is Frege's, though I suppose it had been emerging for a couple of centuries before him. I like the Greek approach, and would love to see that reunited with the supposedly quite different modern view. (Keith Hossack is attempting it). |
| 14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
| Full Idea: A relation is 'Euclidean' if aRb and aRc imply bRc. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
| A reaction: If a thing has a relation to two separate things, then those two things will also have that relation between them. If I am in the same family as Jim and as Jill, then Jim and Jill are in the same family. |
| 14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
| Full Idea: A de dicto necessary truth says that something is φ, that this proposition is a necessary truth, i.e. that in every accessible world something (but not necessarily the same thing in each world) is φ. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.2.1) | |
| A reaction: At last, a really clear and illuminating account of this term! The question is then invited of what is the truthmaker for a de dicto truth, assuming that the objects themselves are truthmakers for de re truths. |
| 19091 | Seeing reality mathematically makes it an object of thought, not of experience [Macbeth] |
| Full Idea: As mathematically understood, the world is not an object of experience but instead an object of thought. | |
| From: Danielle Macbeth (Pragmatism and Objective Truth [2007], p.183) | |
| A reaction: Since I am keen on citing biology to show that science does not have to be mathematical, this nicely shows that there is something wrong with a science which places a large gap between itself and the world. |
| 19088 | For pragmatists a concept means its consequences [Macbeth] |
| Full Idea: In the pragmatist view, the meaning of a concept is exhausted by its consequences. | |
| From: Danielle Macbeth (Pragmatism and Objective Truth [2007], p.173) | |
| A reaction: I'm unclear why the concept of a volcanic eruption only concerns its dire consequences, and is supposed to contain nothing of its causes. Pragmatists seem to be all future, and no past. Very American. |
| 6005 | Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley] |
| Full Idea: Hermarchus said that animal killing is justified by considerations of human safety and nourishment and by animals' inability to form contractual relations of justice with us. | |
| From: report of Hermarchus (fragments/reports [c.270 BCE]) by David A. Sedley - Hermarchus | |
| A reaction: Could the last argument be used to justify torturing animals? Or could we eat a human who was too brain-damaged to form contracts? |