Combining Texts

All the ideas for 'Letters to Oldenburg', 'works' and 'Remarks on axiomatised set theory'

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9 ideas

4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
Axiomatising set theory makes it all relative [Skolem]
     Full Idea: Axiomatising set theory leads to a relativity of set-theoretic notions, and this relativity is inseparably bound up with every thoroughgoing axiomatisation.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.296)
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
If a 1st-order proposition is satisfied, it is satisfied in a denumerably infinite domain [Skolem]
     Full Idea: Löwenheim's theorem reads as follows: If a first-order proposition is satisfied in any domain at all, it is already satisfied in a denumerably infinite domain.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.293)
6. Mathematics / B. Foundations for Mathematics / 1. Foundations for Mathematics
Integers and induction are clear as foundations, but set-theory axioms certainly aren't [Skolem]
     Full Idea: The initial foundations should be immediately clear, natural and not open to question. This is satisfied by the notion of integer and by inductive inference, by it is not satisfied by the axioms of Zermelo, or anything else of that kind.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.299)
     A reaction: This is a plea (endorsed by Almog) that the integers themselves should be taken as primitive and foundational. I would say that the idea of successor is more primitive than the integers.
6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / b. Against mathematical platonism
Mathematician want performable operations, not propositions about objects [Skolem]
     Full Idea: Most mathematicians want mathematics to deal, ultimately, with performable computing operations, and not to consist of formal propositions about objects called this or that.
     From: Thoralf Skolem (Remarks on axiomatised set theory [1922], p.300)
7. Existence / A. Nature of Existence / 6. Criterion for Existence
To be is to have causal powers [Alexander,S]
     Full Idea: To be is to have causal powers.
     From: Samuel Alexander (works [1927], §4), quoted by Jaegwon Kim - Nonreductivist troubles with ment.causation
     A reaction: This is sometimes called Alexander's Principle. It is first found in Plato, and is popular with physicalists, but there are problem cases... A thing needs to exist in order to have causal powers. To exist is more than to be perceived.
17. Mind and Body / A. Mind-Body Dualism / 6. Epiphenomenalism
Epiphenomenalism makes the mind totally pointless [Alexander,S]
     Full Idea: Epiphenomenalism supposes something to exist in nature which has nothing to do and no purpose to serve.
     From: Samuel Alexander (works [1927]), quoted by Jaegwon Kim - Philosophy of Mind p.129
     A reaction: An objection, but not, I think, a strong one. The fact, for example, that sweat is shiny is the result of good evolutionary reasons, but I cannot think of any purpose which it serves. All events which are purposeful are likely to have side-effects.
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / f. Ethical non-cognitivism
Whether nature is beautiful or orderly is entirely in relation to human imagination [Spinoza]
     Full Idea: I do not attribute to nature either beauty or deformity, order or confusion. Only in relation to our imagination can things be called beautiful or deformed, ordered or confused.
     From: Baruch de Spinoza (Letters to Oldenburg [1665], 1665?)
     A reaction: This is clearly a statement of Hume's famous later opinion that there are no values ('ought') in nature ('is'). It is a rejection of Aristotelian and Greek teleology. It is hard to argue with, but I have strong sales resistance, rooted in virtue theory.
28. God / A. Divine Nature / 3. Divine Perfections
God is a being with infinite attributes, each of them infinite or perfect [Spinoza]
     Full Idea: I define God as a being consisting in infinite attributes, whereof each is infinite or supremely perfect.
     From: Baruch de Spinoza (Letters to Oldenburg [1665], 1661)
     A reaction: This seems to me the glorious culmination of the hyperbolic conception of God that expands steadily from wood spirits through Zeus, to eventually mop up everything in nature, and then everything that can be imagined beyond nature. All very silly.
28. God / B. Proving God / 3. Proofs of Evidence / e. Miracles
Trying to prove God's existence through miracles is proving the obscure by the more obscure [Spinoza]
     Full Idea: Those who endeavour to establish God's existence and the truth of religion by means of miracles seek to prove the obscure by what is more obscure.
     From: Baruch de Spinoza (Letters to Oldenburg [1665], 1675?)
     A reaction: Nicely put. On the whole this has to be right, but one must leave open a possibility. If there is a God, and He seeks to prove Himself by a deed, are we saying this is impossible? Divine intervention might be the best explanation of something.