13913
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The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward]
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Full Idea:
There are four 'perfect syllogisms': Barbara (every M is P, every S is M, so every S is P); Celarent (no M is P, every S is M, so no S is P); Darii (every M is P, some S is M, so some S is P); Ferio (no M is P, some S is M, so some S is not P).
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From:
Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8)
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A reaction:
The four names are mnemonics from medieval universities.
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13916
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Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward]
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Full Idea:
Term logic begins with expressions and two 'term functors'. Any simple letter is a 'term', any term prefixed by a minus ('-') is a 'negative term', and any pair of terms flanking a plus ('+') is a 'compound term'. Parenthese are used for grouping.
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From:
Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8)
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A reaction:
[see Engelbretsen and Sayward for the full formal system]
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13849
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Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward]
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Full Idea:
Classical logic rests on the concepts of truth and falsity (and usually makes use of a semantic theory based on models), whereas constructivist logic accounts for inference in terms of defense and refutation.
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From:
Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Intro)
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A reaction:
My instincts go with the classical view, which is that inferences do not depend on the human capacity to defend them, but sit there awaiting revelation. My view isn't platonist, because I take the inferences to be rooted in the physical world.
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23060
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The good is not relative, but is rooted in facts about human needs [Santayana]
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Full Idea:
The good is by no means relative to opinion, but is rooted in the unconscious and fatal nature of living beings, a nature which predetermines for them the difference between foods and poisons, happiness and misery.
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From:
George Santayana (Platonism and the Spiritual Life [1927], p.3), quoted by John Gray - Seven Types of Atheism 6
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A reaction:
That is, he concedes that the good is relative to human beings, but that the relevant facts about human beings are not relative. I think he has the correct picture. The key point is that the good is 'rooted' in something, and doesn't just float free.
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