Combining Philosophers

Ideas for Lynch,MP/Glasgow,JM, H. Paul Grice and Sextus Empiricus

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3 ideas

5. Theory of Logic / B. Logical Consequence / 8. Material Implication
12196 A valid hypothetical syllogism is 'that which does not begin with a truth and end with a falsehood' [Sext.Empiricus]
     Full Idea: Philo (of Megara) says that a valid hypothetical syllogism is 'that which does not begin with a truth and end with a falsehood,' as for instance the syllogism 'If it is day, I converse,' when in fact it is day and I am conversing.
     From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], II.110)
     A reaction: Russell endorses this, and Rumfitt quotes it as the classic case of denying that there is any modal aspect (such as 'logical necessity') involved in logical consequence. He labels it 'material or Philonian consequence'.
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
6020 'Man is a rational mortal animal' is equivalent to 'if something is a man, that thing is a rational mortal animal' [Sext.Empiricus]
     Full Idea: Definitions are identical to universal propositions in meaning, and only differ in syntax, for whoever says 'Man is a rational mortal animal' says the same thing in meaning as whoever says 'If something is a man, that thing is a rational mortal animal'.
     From: Sextus Empiricus (Against the Professors (six books) [c.180], 11.8)
     A reaction: How strikingly like Bertrand Russell's interest and solutions. Sextus shows a straightforward interest in logical form, of a kind we associate with the twentieth century. Did Sextus Empiricus invent quantification?
5. Theory of Logic / L. Paradox / 7. Paradoxes of Time
1902 Since Socrates either died when he was alive (a contradiction) or died when he was dead (meaningless), he didn't die [Sext.Empiricus]
     Full Idea: If Socrates died, he died either when he lived or when he died; so he was either dead when he was alive, or he was twice dead when he was dead. So he didn't die.
     From: Sextus Empiricus (Outlines of Pyrrhonism [c.180], III.111)
     A reaction: One of my favourites. Of all the mysteries facing us, the one that boggles me most is how anything can happen in the 'present' moment, if the present is just the overlap point between past and future.