Combining Texts

Ideas for 'fragments/reports', 'The Possibility of Metaphysics' and 'The Trouble with Being Born'

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4 ideas

5. Theory of Logic / B. Logical Consequence / 5. Modus Ponens
8078 Modus ponens is one of five inference rules identified by the Stoics [Chrysippus, by Devlin]
     Full Idea: Modus ponens is just one of the five different inference rules identified by the Stoics.
     From: report of Chrysippus (fragments/reports [c.240 BCE]) by Keith Devlin - Goodbye Descartes Ch.2
     A reaction: Modus ponens strikes me as being more like a definition of implication than a 'rule'. Implication is what gets you from one truth to another. All the implications of a truth must also be true.
5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle
6023 Every proposition is either true or false [Chrysippus, by Cicero]
     Full Idea: We hold fast to the position, defended by Chrysippus, that every proposition is either true or false.
     From: report of Chrysippus (fragments/reports [c.240 BCE]) by M. Tullius Cicero - On Fate ('De fato') 38
     A reaction: I am intrigued to know exactly how you defend this claim. It may depend what you mean by a proposition. A badly expressed proposition may have indeterminate truth, quite apart from the vague, the undecidable etc.
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / c. not
23066 Negation doesn't arise from reasoning, but from deep instincts [Cioran]
     Full Idea: Negation never proceeds from reasoning but from something much more obscure and old. Arguments come afterward, to justify and sustain it. Every no rises out of the blood.
     From: E.M. Cioran (The Trouble with Being Born [1973], 02)
     A reaction: Music to my ears. In the Fregean era no one is allowed to talk about the origins of logical relations in the universal facts of physical existence. You can watch dogs saying no.
5. Theory of Logic / G. Quantification / 3. Objectual Quantification
8312 It is better if the existential quantifier refers to 'something', rather than a 'thing' which needs individuation [Lowe]
     Full Idea: If we take the existential quantifier to mean 'there is at least one thing that' then its value must qualify as one thing, individuable in principle. ...So I propose to read it as 'there is something that', which implies nothing about individuability.
     From: E.J. Lowe (The Possibility of Metaphysics [1998], 11)
     A reaction: All sorts of doubts about the existential quantifier seem to be creeping in nowadays (e.g. Ideas 6067, 6069, 8250). Personally I am drawn to the sound of 'free logic', Idea 8250, which drops existential claims. This would reduce metaphysical confusion.