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Single Idea 16854

[filed under theme 2. Reason / B. Laws of Thought / 4. Contraries ]

Full Idea

All pairs of contraries entail a pair of contradictories, since one member of such a pair always entails the negation of the other. P&Q and not-P are contraries, but the first entails P, which is contradictory of not-P.

Gist of Idea

Contrary pairs entail contradictions; one member entails negation of the other

Source

Peter Lipton (Inference to the Best Explanation (2nd) [2004], 09 'Is the best')

Book Ref

Lipton,Peter: 'Inference to the Best Explanation (2nd ed)' [Routledge 2004], p.156


The 9 ideas with the same theme [could both be false, but can't both be true]:

Only one thing can be contrary to something [Plato]
The contrary of good is bad, but the contrary of bad is either good or another evil [Aristotle]
Both sides of contraries need not exist (as health without sickness, white without black) [Aristotle]
From one thing alone we can infer its contrary [Aristotle]
Contraries are by definition as far distant as possible from one another [Aristotle]
In "Callias is just/not just/unjust", which of these are contraries? [Aristotle]
There is no middle ground in contradiction, but there is in contrariety [Aristotle]
Two falsehoods can be contrary to one another [Aristotle]
Contrary pairs entail contradictions; one member entails negation of the other [Lipton]