12 ideas
11970 | Logicians like their entities to exhibit a maximum degree of purity [Kaplan] |
Full Idea: Logicians like their entities to exhibit a maximum degree of purity. | |
From: David Kaplan (Transworld Heir Lines [1967], p.97) | |
A reaction: An important observation, which explains why the modern obsession with logic has often led us down the metaphysical primrose path to ontological hell. |
18256 | Quantity is inconceivable without the idea of addition [Frege] |
Full Idea: There is so intimate a connection between the concepts of addition and of quantity that one cannot begin to grasp the latter without the former. | |
From: Gottlob Frege (Rechnungsmethoden (dissertation) [1874], p.2), quoted by Michael Dummett - Frege philosophy of mathematics 22 'Quantit' | |
A reaction: Frege offers good reasons for making cardinals prior to ordinals, though plenty of people disagree. |
9831 | Geometry appeals to intuition as the source of its axioms [Frege] |
Full Idea: The elements of all geometrical constructions are intuitions, and geometry appeals to intuition as the source of its axioms. | |
From: Gottlob Frege (Rechnungsmethoden (dissertation) [1874], Ch.6), quoted by Michael Dummett - Frege philosophy of mathematics | |
A reaction: Very early Frege, but he stuck to this view, while firmly rejecting intuition as a source of arithmetic. Frege would have known well that Euclid's assumption about parallels had been challenged. |
11969 | Models nicely separate particulars from their clothing, and logicians often accept that metaphysically [Kaplan] |
Full Idea: The use of models is so natural to logicians ...that they sometimes take seriously what are only artefacts of the model, and adopt a bare particular metaphysics. Why? Because the model so nicely separates the bare particular from its clothing. | |
From: David Kaplan (Transworld Heir Lines [1967], p.97) | |
A reaction: See also Idea 11970. I think this observation is correct, and incredibly important. We need to keep quite separate the notion of identity in conceptual space from our notion of identity in the actual world. The first is bare, the second fat. |
15642 | If kinds depend only on what can be observed, many underlying essences might produce the same kind [Eagle] |
Full Idea: If the kinds there are depend not on the essences of the objects but on their observed distinguishing particulars, ...then for any kind that we think there is, it is possible that there are many underlying essences which are observably indistinguishable. | |
From: Antony Eagle (Locke on Essences and Kinds [2005], IV) | |
A reaction: Eagle is commenting on Locke's reliance on nominal essences. This seems to be the genuine problem with jadeite and nephrite (both taken to be 'jade'), or with 'fool's gold'. This isn't an objection to Locke; it just explains the role of science. |
15645 | Nominal essence are the observable properties of things [Eagle] |
Full Idea: It is clear the nominal essences really are the properties of the things which have them: they are (a subset of) the observable properties of the things. | |
From: Antony Eagle (Locke on Essences and Kinds [2005], IV) | |
A reaction: I think this is wrong. The surface characteristics are all that is available to us, so our classifications must be based on those, but it is on the ideas of them, not their intrinsic natures. That is empiricsm! What makes the properties 'essential'? |
15643 | Nominal essence mistakenly gives equal weight to all underlying properties that produce appearances [Eagle] |
Full Idea: Nominal essence does not allow for gradations in significance for the underlying properties. Those are all essential for the object behaving as it observably does, and they must all be given equal weight when deciding what the object does. | |
From: Antony Eagle (Locke on Essences and Kinds [2005], IV) | |
A reaction: This is where 'scientific' essentialism comes in. If we take one object, or one kind of object, in isolation, Eagle is right. When we start to compare, and to set up controlled conditions tests, we can dig into the 'gradations' he cares about. |
11971 | The simplest solution to transworld identification is to adopt bare particulars [Kaplan] |
Full Idea: If we adopt the bare particular metaphysical view, we have a simple solution to the transworld identification problem: we identify by bare particulars. | |
From: David Kaplan (Transworld Heir Lines [1967], p.98) | |
A reaction: See Ideas 11969 and 11970 on this idea. The problem with bare particulars is that they can change their properties utterly, so that Aristotle in the actual world can be a poached egg in some possible world. We need essences. |
11973 | Unusual people may have no counterparts, or several [Kaplan] |
Full Idea: An extremely vivid person might have no counterparts, and Da Vinci seems to me to have more than one essence. Bertrand Russell is clearly the counterpart of at least three distinct persons in some more plausible world. | |
From: David Kaplan (Transworld Heir Lines [1967], p.100) | |
A reaction: Lewis prefers the notion that there is at most one counterpart, the 'closest' entity is some world. I think he also claims there is at least one counterpart. I like Kaplan's relaxed attitude to these things, which has more explanatory power. |
11972 | Essence is a transworld heir line, rather than a collection of properties [Kaplan] |
Full Idea: I prefer to think of essence as a transworld heir line, rather than as the more familiar collection of properties, because the latter too much suggests the idea of a fixed and final essential description. | |
From: David Kaplan (Transworld Heir Lines [1967], p.100) | |
A reaction: He is sympathetic to the counterpart idea, and close to Lewis's view of essences, as the intersection of counterparts. I like his rebellion against fixed and final descriptions, but am a bit doubtful about his basic idea. Causation should be involved. |
11967 | Sentences might have the same sense when logically equivalent - or never have the same sense [Kaplan] |
Full Idea: Among the proposals for conditions under which two sentences have the same ordinary sense, the most liberal (Carnap and Church) is that they be logically equivalent, and the most restrictive (Benson Mates) is that they never have the same sense. | |
From: David Kaplan (Transworld Heir Lines [1967], p.89) | |
A reaction: Personally I would move the discussion to the level of the propositions being expressed before I attempted a solution. |
15641 | Kinds are fixed by the essential properties of things - the properties that make it that kind of thing [Eagle] |
Full Idea: The natural thought is to think that real kinds are given only by classification on the basis of essential properties: properties that make an object the kind of thing that it is. | |
From: Antony Eagle (Locke on Essences and Kinds [2005], II) | |
A reaction: Circularity alert! Circularity alert! Essence gives a thing its kind - and hence we can see what the kind is? Test for a trivial property! Eagle is not unaware of these issues. Does he mean 'necessary' rather than 'essential'? |