Combining Texts

Ideas for 'The Sign of Four', 'Logical Properties' and 'Summula philosophiae naturalis'

unexpand these ideas     |    start again     |     choose another area for these texts

display all the ideas for this combination of texts


12 ideas

9. Objects / F. Identity among Objects / 1. Concept of Identity
Identity propositions are not always tautological, and have a key epistemic role [McGinn]
     Full Idea: Identity propositions are not always analytic or a priori (as Frege long ago taught us) so there is nothing trivial about such propositions; the claim of redundancy ignores the epistemic role that the concept of identity plays.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: He is referring to Frege's Morning Star/Evening Star distinction (Idea 4972). Wittgenstein wanted to eliminate our basic metaphysics by relabelling it as analytic or tautological, but his project failed. Long live metaphysics!
9. Objects / F. Identity among Objects / 2. Defining Identity
Identity is as basic as any concept could ever be [McGinn]
     Full Idea: Identity has a universality and basicness that is hard to overstate; concepts don't get more basic than this - or more indispensable.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: I agree with this. It seems to me to follow that the natural numbers are just as basic, because they are entailed by the separateness of the identities of things. And the whole of mathematics is the science of the patterns within these numbers.
9. Objects / F. Identity among Objects / 4. Type Identity
Type-identity is close similarity in qualities [McGinn]
     Full Idea: Two things are said to be type-identical when they are similar enough to be declared qualitatively identical.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: A simple point which brings out the fact that type-identity is unlikely to be any sort of true identity (unless there is absolutely no different at all between two electrons, say).
Qualitative identity is really numerical identity of properties [McGinn]
     Full Idea: A statement of so-called qualitative identity is really a statement of numerical identity (that is, identity tout court) about the properties of the objects in question - assuming that there are genuine universals.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: We might agree that two cars are type-identical, even though (under the microscope) we decided that none of their properties were absolutely identical.
Qualitative identity can be analysed into numerical identity of the type involved [McGinn]
     Full Idea: We can analyse qualitative identity in terms of numerical identity, by saying that x and y are type-identical if there is a single type T that x and y both are, i.e. they both exemplify the same type.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: This just seems to shift the problem onto the words 'are' and 'exemplify'. This takes us back to the problem of things 'partaking' of Plato's Forms. Better to say that qualitative identity isn't identity - it is resemblance (see Idea 6045).
It is best to drop types of identity, and speak of 'identity' or 'resemblance' [McGinn]
     Full Idea: It would be better to drop talk of 'numerical' and 'qualitative' identity altogether, speaking instead simply of identity and resemblance.
     From: Colin McGinn (Logical Properties [2000], Ch.1 n4)
     A reaction: This is the kind of beautifully simple proposal I pay analytical philosophers to come up with. I will attempt in future to talk either of 'identity' (which is strict), or 'resemblance' (which comes in degrees).
9. Objects / F. Identity among Objects / 5. Self-Identity
Existence is a property of all objects, but less universal than self-identity, which covers even conceivable objects [McGinn]
     Full Idea: Existence is a property universal to all objects that exist, somewhat like self-identity, but less universal, because self-identity holds of all conceivable objects, not merely those that happen to exist.
     From: Colin McGinn (Logical Properties [2000], Ch.2)
     A reaction: This is a splendidly defiant response to the Kantian slogan that 'existence is not a predicate', and I find McGinn persuasive. I can still not find anyone to explain to me exactly what a property is, so I will reserve judgement.
Sherlock Holmes does not exist, but he is self-identical [McGinn]
     Full Idea: Sherlock Holmes does not exist, but he is self-identical (he is certainly not indentical to Dr Watson).
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: Most significant. Identity does not entail existence; identity is necessary for existence (I think) but not sufficient. But the notion of existence might be prior to the notion of identity, and the creation of Holmes be parasitic on real existence.
9. Objects / F. Identity among Objects / 6. Identity between Objects
All identity is necessary, though identity statements can be contingently true [McGinn]
     Full Idea: All identity is necessary, although there can be contingently true identity statements - those that contain non-rigid designators.
     From: Colin McGinn (Logical Properties [2000], Ch.1 n5)
     A reaction: A nice case of the need to keep epistemology and ontology separate. An example might be 'The Prime Minister wears a wig', where 'Prime Minister' may not be a rigid designator. 'Winston wears a wig' will be necessary, if true (which it wasn't).
9. Objects / F. Identity among Objects / 8. Leibniz's Law
Leibniz's Law says 'x = y iff for all P, Px iff Py' [McGinn]
     Full Idea: Leibniz's Law says 'x = y iff for all P, Px iff Py'.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: That is, two things are the same if when we say that one thing (x) has a property (P), then we are saying that the other thing (y) also has the property. A usefully concise statement of the Law.
Leibniz's Law is so fundamental that it almost defines the concept of identity [McGinn]
     Full Idea: Leibniz's Law, which a defender of relative identity might opt to reject, is so fundamental to the notion of identity that rejecting it amounts to changing the subject.
     From: Colin McGinn (Logical Properties [2000], Ch.1 n8)
     A reaction: The Law here is the 'indiscernibility of identicals'. I agree with McGinn, and anyone who loses their grip on this notion of identity strikes me as losing all grip on reality, and threatening their own sanity (well, call it their 'philosophical sanity').
Leibniz's Law presupposes the notion of property identity [McGinn]
     Full Idea: Leibniz's Law presupposes the notion of property identity.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: A very important observation, because it leads to recognition of the way in which basic concepts and categories of thought interconnect. Which is more metaphysically basic, identity or properties? It is not easy to say…