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9. Objects / A. Existence of Objects / 2. Abstract Objects / b. Need for abstracta

[why we might postulate non-physical objects]

5 ideas
Our conceptual scheme becomes more powerful when we posit abstract objects [Quine]
     Full Idea: There is no denying the access of power that accrues to our conceptual scheme through the positing of abstract objects.
     From: Willard Quine (Speaking of Objects [1960], §5)
     A reaction: This seems right, both in its use of the word 'posit', and in its general pragmatic claim. So why? If they enable us to grapple with the world better, it must be because of their power of generalisation. They are nets thrown over chunks of reality.
We need a logical use of 'object' as predicate-worthy, and an 'ontological' use [Strawson,P]
     Full Idea: There is a good case for a conservative reform of the word 'object'. Objects in the 'logical' sense would be all predicate-worthy identifiabilia whatever. Objects in the 'ontological' sense would form one ontological category among many others.
     From: Peter F. Strawson (Entity and Identity [1978], I n4)
     A reaction: This ambiguity has caused me no end of confusion (and irritation!). I wish philosophers wouldn't hijack perfectly good English words and give them weird meanings. Nice to have a distinguished fellow like Strawson make this suggestion.
Physics is full of non-physical entities, such as space-vectors [Putnam]
     Full Idea: Physics is full of references to such 'non-physical' entities as state-vectors, Hamiltonians, Hilbert space etc.
     From: Hilary Putnam (Philosophy of Logic [1971], Ch.2)
     A reaction: I take these to be concepts which are 'abstracted' from the physical facts, and so they don't strike me as being much of an ontological problem, or an objection to nominalism (which Putnam takes them to be).
If we can intuitively apprehend abstract objects, this makes them observable and causally active [Dummett]
     Full Idea: For intuitionists, it ceases to be true that abstract objects are not observable and cannot be involved in causal interaction, since such intuitive apprehension of them may be regarded as just such an interaction.
     From: Michael Dummett (Frege Philosophy of Language (2nd ed) [1973], Ch.14)
     A reaction: I would say that since abstract objects can be involved in causal interactions, in the mind, and since the mind is entirely physical (oh yes), this makes abstract objects entirely physical, which may come as a shock to some people.
Abstract objects were a bad way of explaining the structure in mathematics [Kitcher]
     Full Idea: The original introduction of abstract objects was a bad way of doing justice to the insight that mathematics is concerned with structure.
     From: Philip Kitcher (The Nature of Mathematical Knowledge [1984], 06.1)
     A reaction: I'm a fan of explanations in metaphysics, and hence find the concept of 'bad' explanations in metaphysics particularly intriguing.