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13342
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Carnap defined consequence by contradiction, but this is unintuitive and changes with substitution [Tarski on Carnap]
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Full Idea:
Carnap proposed to define consequence as 'sentence X follows from the sentences K iff the sentences K and the negation of X are contradictory', but 1) this is intuitively impossible, and 2) consequence would be changed by substituting objects.
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From:
comment on Rudolph Carnap (The Logical Syntax of Language [1934], p.88-) by Alfred Tarski - The Concept of Logical Consequence p.414
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A reaction:
This seems to be the first step in the ongoing explicit discussion of the nature of logical consequence, which is now seen by many as the central concept of logic. Tarski brings his new tool of 'satisfaction' to bear.
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13251
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Each person is free to build their own logic, just by specifying a syntax [Carnap]
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Full Idea:
In logic, there are no morals. Everyone is at liberty to build his own logic, i.e. his own form of language. All that is required is that he must state his methods clearly, and give syntactical rules instead of philosophical arguments.
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From:
Rudolph Carnap (The Logical Syntax of Language [1934], §17), quoted by JC Beall / G Restall - Logical Pluralism 7.3
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A reaction:
This is understandable, but strikes me as close to daft relativism. If I specify a silly logic, I presume its silliness will be obvious. By what criteria? I say the world dictates the true logic, but this is a minority view.
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19424
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Knowledge needs clarity, distinctness, and adequacy, and it should be intuitive [Leibniz]
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Full Idea:
Knowledge is either obscure or clear; clear ideas are either indistinct or distinct; distinct ideas are either adequate or inadequate, symbolic or intuitive; perfect knowledge is that which is both adequate and intuitive.
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From:
Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.283)
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A reaction:
This is Leibniz's expansion of Descartes's idea that knowledge rests on 'clear and distinct conceptions'. The ultimate target seems to be close to an Aristotelian 'real definition', which is comprehensive and precise. Does 'intuitive' mean coherent?
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19425
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In the schools the Four Causes are just lumped together in a very obscure way [Leibniz]
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Full Idea:
In the schools the four causes are lumped together as material, formal, efficient, and final causes, but they have no clear definitions, and I would call such a judgment 'obscure'.
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From:
Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.283)
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A reaction:
He picks this to illustrate what he means by 'obscure', so he must feel strongly about it. Elsewhere Leibniz embraces efficient and final causes, but says little of the other two. This immediately become clearer as the Four Modes of Explanation.
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20713
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God must be fit for worship, but worship abandons morally autonomy, but there is no God [Rachels, by Davies,B]
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Full Idea:
Rachels argues 1) If any being is God, he must be a fitting object of worship, 2) No being could be a fitting object of worship, since worship requires the abandonment of one's role as an autonomous moral agent, so 3) There cannot be a being who is God.
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From:
report of James Rachels (God and Human Attributes [1971], 7 p.334) by Brian Davies - Introduction to the Philosophy of Religion 9 'd morality'
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A reaction:
Presumably Lionel Messi can be a fitting object of worship without being God. Since the problem is with being worshipful, rather than with being God, should I infer that Messi doesn't exist?
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