8945
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Fuzzy logic has many truth values, ranging in fractions from 0 to 1 [Fisher]
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Full Idea:
In fuzzy logic objects have properties to a greater or lesser degree, and truth values are given as fractions or decimals, ranging from 0 to 1. Not-p is defined as 1-p, and other formula are defined in terms of maxima and minima for sets.
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From:
Jennifer Fisher (On the Philosophy of Logic [2008], 07.II)
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A reaction:
The question seems to be whether this is actually logic, or a recasting of probability theory. Susan Haack attacks it. If logic is the study of how truth is preserved as we move between propositions, then 0 and 1 need a special status.
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8951
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Classical logic is: excluded middle, non-contradiction, contradictions imply all, disjunctive syllogism [Fisher]
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Full Idea:
For simplicity, we can say that 'classical logic' amounts to the truth of four sentences: 1) either p or not-p; 2) it is not the case that both p and not-p; 3) from p and not-p, infer q; 4) from p or q and not-p, infer q.
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From:
Jennifer Fisher (On the Philosophy of Logic [2008], 12.I)
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A reaction:
[She says there are many ways of specifying classical logic] Intuition suggests that 2 and 4 are rather hard to dispute, while 1 is ignoring some grey areas, and 3 is totally ridiculous. There is, of course, plenty of support for 3!
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8950
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Logic formalizes how we should reason, but it shouldn't determine whether we are realists [Fisher]
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Full Idea:
Even if one is inclined to be a realist about everything, it is hard to see why our logic should be the determiner. Logic is supposed to formalize how we ought to reason, but whether or not we should be realists is a matter of philosophy, not logic.
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From:
Jennifer Fisher (On the Philosophy of Logic [2008], 09.I)
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A reaction:
Nice to hear a logician saying this. I do not see why talk in terms of an object is a commitment to its existence. We can discuss the philosopher's stone, or Arthur's sword, or the Loch Ness monster, or gravitinos, with degrees of commitment.
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3425
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Reduction has been defined as deriving one theory from another by logic and maths [Nagel,E, by Kim]
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Full Idea:
Ernest Nagel defines reduction as the possibility of deriving all laws of one theory by logic and mathematics to another theory, with appropriate 'bridging principles' (either definitions, or empirical laws) connecting the expressions of the two theories.
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From:
report of Ernest Nagel (The Structure of Science [1961]) by Jaegwon Kim - Philosophy of Mind p.213
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A reaction:
This has been labelled as 'weak' reduction, where 'strong' reduction would be identity, as when lightning is reduced to electrical discharge. You reduce x by showing that it is y in disguise.
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8944
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Vagueness can involve components (like baldness), or not (like boredom) [Fisher]
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Full Idea:
Vague terms come in at least two different kinds: those whose constituent parts come in discrete packets (bald, rich, red) and those that don't (beauty, boredom, niceness).
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From:
Jennifer Fisher (On the Philosophy of Logic [2008], 07.II)
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A reaction:
The first group seem to be features of the external world, and the second all occur in the mind. Baldness may be vague, but presumably hairs are (on the whole) not. Nature doesn't care whether someone is actually 'bald' or not.
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12434
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Why is this necessary, and what is necessity in general; why is this necessary truth true, and why necessary? [Hale]
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Full Idea:
We must distinguish between explaining particular necessities and explaining necessity in general; and we ought to distinguish between explaining, in regard to any necessary truth, why it is true, and explaining why it is necessary.
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From:
Bob Hale (The Source of Necessity [2002], p.308)
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A reaction:
Useful. The pluralist view I associate with Fine says we can explain types of necessity, but not necessity in general. If we seek truthmakers, there is a special case of what adds the necessity to the truth.
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12433
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If necessity rests on linguistic conventions, those are contingent, so there is no necessity [Hale]
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Full Idea:
If the alleged necessity, e,g, 2+2=4, really does depend upon a convention governing the use of the words in which we state it, and the existence of that convention is merely a contingent matter, then it can't after all be necessary.
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From:
Bob Hale (The Source of Necessity [2002], p.302)
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A reaction:
[Hale is citing Blackburn for this claim] Hale suggests replies, by keeping truth and meaning separate, and involving laws of logic. Blackburn clearly has a good point.
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12436
|
Concept-identities explain how we know necessities, not why they are necessary [Hale]
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Full Idea:
It seems to me that identity-relations among concepts have more to do with explaining how we know that vixens are female foxes etc., than with explaining why it is necessary, and, more generally, with explaining why some necessities are knowable a priori.
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From:
Bob Hale (The Source of Necessity [2002], P.313)
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A reaction:
Hale rejects the conceptual and conventional accounts of necessity, in favour of the essentialist view. This strikes me as a good suggestion of Hale's, since I agree with him about the essentialism.
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