Combining Texts

All the ideas for 'fragments/reports', 'Questions on Aristotle's Posterior Analytics' and 'The Logical Syntax of Language'

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5 ideas

5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence

13342	Carnap defined consequence by contradiction, but this is unintuitive and changes with substitution [Tarski on Carnap]
	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.
	From: comment on Rudolph Carnap (The Logical Syntax of Language [1934], p.88-) by Alfred Tarski - The Concept of Logical Consequence p.414
	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.

5. Theory of Logic / C. Ontology of Logic / 4. Logic by Convention

13251	Each person is free to build their own logic, just by specifying a syntax [Carnap]
	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.
	From: Rudolph Carnap (The Logical Syntax of Language [1934], §17), quoted by JC Beall / G Restall - Logical Pluralism 7.3
	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.

12. Knowledge Sources / B. Perception / 2. Qualities in Perception / b. Primary/secondary

16726	Why can't we deduce secondary qualities from primary ones, if they cause them? [Buridan]
	Full Idea: The entire difficulty in this question is why through a knowledge of the primary tangible qualities we cannot come to a knowledge of flavors or odors, since these are their causes, since we often go from knowledge of causes to knowing their effects.
	From: Jean Buridan (Questions on Aristotle's Posterior Analytics [1344], I.28c), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 22.2
	A reaction: He is commenting on Idea 16725. Still a nice puzzle in the philosophy of mind. Will neuroscientists ever be able to infer to actual character of some quale, just from the structures of the neurons?

25. Social Practice / E. Policies / 5. Education / b. Education principles

13304	Learned men gain more in one day than others do in a lifetime [Posidonius]
	Full Idea: In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes.
	From: Posidonius (fragments/reports [c.95 BCE]), quoted by Seneca the Younger - Letters from a Stoic 078
	A reaction: These remarks endorsing the infinite superiority of the educated to the uneducated seem to have been popular in late antiquity. It tends to be the religions which discourage great learning, especially in their emphasis on a single book.

27. Natural Reality / D. Time / 1. Nature of Time / d. Time as measure

20820	Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus]
	Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness.
	From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42
	A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them.