Combining Philosophers

All the ideas for Douglas Lackey, Dag Prawitz and Erving Goffman

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8 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
13831 Logic is based on transitions between sentences [Prawitz]
     Full Idea: I agree entirely with Dummett that the right way to answer the question 'what is logic?' is to consider transitions between sentences.
     From: Dag Prawitz (Gentzen's Analysis of First-Order Proofs [1974], §04)
     A reaction: I always protest at this point that reliance on sentences is speciesism against animals, who are thereby debarred from reasoning. See the wonderful Idea 1875 of Chrysippus. Hacking's basic suggestion seems right. Transition between thoughts.
5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
13827 Logical consequence isn't a black box (Tarski's approach); we should explain how arguments work [Prawitz]
     Full Idea: Defining logical consequence in the way Tarski does is a rather meagre result, treating an argument as a black box, observing input and output, while disregarding inner structure. We should define logical consequence on the basis of valid arguments.
     From: Dag Prawitz (On the General Idea of Proof Theory [1974], §2)
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
13825 Natural deduction introduction rules may represent 'definitions' of logical connectives [Prawitz]
     Full Idea: With Gentzen's natural deduction, we may say that the introductions represent, as it were, the 'definitions' of the logical constants. The introductions are not literally understood as 'definitions'.
     From: Dag Prawitz (Gentzen's Analysis of First-Order Proofs [1974], 2.2.2)
     A reaction: [Hacking, in 'What is Logic? §9' says Gentzen had the idea that his rules actually define the constants; not sure if Prawitz and Hacking are disagreeing]
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
13823 In natural deduction, inferences are atomic steps involving just one logical constant [Prawitz]
     Full Idea: In Gentzen's natural deduction, the inferences are broken down into atomic steps in such a way that each step involves only one logical constant. The steps are the introduction or elimination of the logical constants.
     From: Dag Prawitz (Gentzen's Analysis of First-Order Proofs [1974], 1.1)
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
13826 Model theory looks at valid sentences and consequence, but not how we know these things [Prawitz]
     Full Idea: In model theory, which has dominated the last decades, one concentrates on logically valid sentences, and what follows logically from what, but one disregards questions concerning how we know these things.
     From: Dag Prawitz (On the General Idea of Proof Theory [1974], §1)
5. Theory of Logic / L. Paradox / 5. Paradoxes in Set Theory / b. Cantor's paradox
21554 Sets always exceed terms, so all the sets must exceed all the sets [Lackey]
     Full Idea: Cantor proved that the number of sets in a collection of terms is larger than the number of terms. Hence Cantor's Paradox says the number of sets in the collection of all sets must be larger than the number of sets in the collection of all sets.
     From: Douglas Lackey (Intros to Russell's 'Essays in Analysis' [1973], p.127)
     A reaction: The sets must count as terms in the next iteration, but that is a normal application of the Power Set axiom.
5. Theory of Logic / L. Paradox / 5. Paradoxes in Set Theory / c. Burali-Forti's paradox
21553 It seems that the ordinal number of all the ordinals must be bigger than itself [Lackey]
     Full Idea: The ordinal series is well-ordered and thus has an ordinal number, and a series of ordinals to a given ordinal exceeds that ordinal by 1. So the series of all ordinals has an ordinal number that exceeds its own ordinal number by 1.
     From: Douglas Lackey (Intros to Russell's 'Essays in Analysis' [1973], p.127)
     A reaction: Formulated by Burali-Forti in 1897.
16. Persons / E. Rejecting the Self / 2. Self as Social Construct
8044 Goffman sees the self as no more than a peg on which to hang roles we play [Goffman, by MacIntyre]
     Full Idea: Erving Goffman has liquidated the self into its role-playing, arguing that the self is no more than 'a peg' on which the clothes of the role are hung.
     From: report of Erving Goffman (Presentation of Self in Everyday Life [1959]) by Alasdair MacIntyre - After Virtue: a Study in Moral Theory Ch.3
     A reaction: A rather unsympathetic expression of his view, but it seems to be a widely held view among students of sociology. But then sociologists are almost committed a priori to a social and relativist view of truth, persons, knowledge, religion etc.