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All the ideas for 'fragments/reports', 'The philosophical basis of intuitionist logic' and 'De Mundo Praesenti'

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9 ideas

4. Formal Logic / E. Nonclassical Logics / 2. Intuitionist Logic

18073	Dummett says classical logic rests on meaning as truth, while intuitionist logic rests on assertability [Dummett, by Kitcher]
	Full Idea: Dummett argues that classical logic depends on the choice of the concept of truth as central to the theory of meaning, while for the intuitionist the concept of assertability occupies this position.
	From: report of Michael Dummett (The philosophical basis of intuitionist logic [1973]) by Philip Kitcher - The Nature of Mathematical Knowledge 06.5
	A reaction: Since I can assert any nonsense I choose, this presumably means 'warranted' assertability, which is tied to the concept of proof in mathematics. You can reason about falsehoods, or about uninterpreted variables. Can you 'assert' 'Fx'?

5. Theory of Logic / G. Quantification / 1. Quantification

19057	Classical quantification is an infinite conjunction or disjunction - but you may not know all the instances [Dummett]
	Full Idea: Classical quantification represents an infinite conjunction or disjunction, and the truth-value is determined by the infinite sum or product of the instances ....but this presupposes that all the instances already possess determinate truth-values.
	From: Michael Dummett (The philosophical basis of intuitionist logic [1973], p.246)
	A reaction: In the case of the universal quantifier, Dummett is doing no more than citing the classic empiricism objection to induction - that you can't make the universal claim if you don't know all the instances. The claim is still meaningful, though.

8. Modes of Existence / C. Powers and Dispositions / 4. Powers as Essence

12714	The substantial form is the principle of action or the primitive force of acting [Leibniz]
	Full Idea: The substantial form is the principle of action or the primitive force of acting.
	From: Gottfried Leibniz (De Mundo Praesenti [1686], A6.4.1507-8), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3
	A reaction: The clearest statement of the modification of Aristotle's hylomorphism which Leibniz preferred in his middle period, and which strikes me as an improvement, and about right. Shame that monads got too much of a grip on him, but he was trying to dig deeper.

9. Objects / D. Essence of Objects / 1. Essences of Objects

12743	A true being must (unlike a chain) have united parts, with a substantial form as its subject [Leibniz]
	Full Idea: In a Being one per se a real union is required consisting not in the situation or motion of parts, as in a chain or a house, but in a unique individual principle and subject of attributes and operations, in us a soul and in a body a substantial form.
	From: Gottfried Leibniz (De Mundo Praesenti [1686], A6.4.1506), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
	A reaction: Leibniz is said not to be an essentialist, by making all properties essential, but he is certainly committed to substance, and it sounds like essence here (or one view of essence), when it makes identity possible. This idea is pure Aristotle.

19. Language / A. Nature of Meaning / 4. Meaning as Truth-Conditions

19055	Stating a sentence's truth-conditions is just paraphrasing the sentence [Dummett]
	Full Idea: An ability to state the condition for the truth of a sentence is, in effect, no more than an ability to express the content of the sentence in other words.
	From: Michael Dummett (The philosophical basis of intuitionist logic [1973], p.224)
	A reaction: Alternatively, if you give something other than a paraphrase of the sentence as its meaning (such as a proof of its truth), then you seem to have departed from your target sentence. Can we reduce and eliminate our sentences in this way?

19056	If a sentence is effectively undecidable, we can never know its truth conditions [Dummett]
	Full Idea: If a sentence is effectively undecidable, the condition which must obtain for it to be true is not one which we are capable of recognising whenever it obtains, or of getting ourselves in a position to do so.
	From: Michael Dummett (The philosophical basis of intuitionist logic [1973], p.225)
	A reaction: The instances of 'undecidable' sentences are most clearly seen in mathematics, such as the Continuum Hypothesis or Goldbach's Conjecture, or anything involving vast infinite cardinals. But do you need precise truth-conditions for meaning?

19. Language / A. Nature of Meaning / 6. Meaning as Use

19054	Meaning as use puts use beyond criticism, and needs a holistic view of language [Dummett]
	Full Idea: If use constitutes meaning, it might seem that use is beyond criticism. ....But such an attitude can, ultimately, be supported onlly by the adoption of a holistic view of language.
	From: Michael Dummett (The philosophical basis of intuitionist logic [1973], p.218)
	A reaction: Dummett goes on to say that the rejection of the holistic view of mathematical meaning leads to his preference for intuitionistic logic.

26. Natural Theory / A. Speculations on Nature / 5. Infinite in Nature

1748	Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius]
	Full Idea: Archelaus was the first person to say that the universe is boundless.
	From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3

27. Natural Reality / G. Biology / 3. Evolution

5989	Archelaus said life began in a primeval slime [Archelaus, by Schofield]
	Full Idea: Archelaus wrote that life on Earth began in a primeval slime.
	From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus
	A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea.