11023
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The logical connectives are 'defined' by their introduction rules [Gentzen]
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Full Idea:
The introduction rules represent, as it were, the 'definitions' of the symbols concerned, and the elimination rules are no more, in the final analysis, than the consequences of these definitions.
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From:
Gerhard Gentzen (works [1938]), quoted by Stephen Read - Thinking About Logic Ch.8
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A reaction:
If an introduction-rule (or a truth table) were taken as fixed and beyond dispute, then it would have the status of a definition, since there would be nothing else to appeal to. So is there anything else to appeal to here?
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11213
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Each logical symbol has an 'introduction' rule to define it, and hence an 'elimination' rule [Gentzen]
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Full Idea:
To every logical symbol there belongs precisely one inference figure which 'introduces' the symbol ..and one which 'eliminates' it. The introductions represent the 'definitions' of the symbols concerned, and eliminations are consequences of these.
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From:
Gerhard Gentzen (works [1938], II.5.13), quoted by Ian Rumfitt - "Yes" and "No" III
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A reaction:
[1935 paper] This passage is famous, in laying down the basics of natural deduction systems of logic (ones using only rules, and avoiding axioms). Rumfitt questions whether Gentzen's account gives the sense of the connectives.
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21982
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I only wish I had such eyes as to see Nobody! It's as much as I can do to see real people. [Carroll,L]
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Full Idea:
"I see nobody on the road," said Alice. - "I only wish I had such eyes," the King remarked. ..."To be able to see Nobody! ...Why, it's as much as I can do to see real people."
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From:
Lewis Carroll (C.Dodgson) (Through the Looking Glass [1886], p.189), quoted by A.W. Moore - The Evolution of Modern Metaphysics 07.7
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A reaction:
[Moore quotes this, inevitably, in a chapter on Hegel] This may be a better candidate for the birth of philosophy of language than Frege's Groundwork.
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5064
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Rights are moral significance, or liberty, or right not to be restrained, or entitlement [Mawson]
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Full Idea:
A 'right' can mean 'x counts morally', or 'x is permitted to do this' (liberty), or 'x can't be stopped from doing this' (negative right), or 'someone should provide this for x'.
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From:
Tim Mawson (Animal Rights talk [2003]), quoted by PG - lecture notes
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A reaction:
A useful analysis. It is a useful preliminary to considering whether any of these are natural rights. Personally I am sympathetic to that concept. You cannot deny a person's right to self-defence, even when you are sitting on them. Persons have rights.
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