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Ideas for '', 'Trees, Terms and Truth' and 'fragments/reports'

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7 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt]
     Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation.
     From: Ian Rumfitt ("Yes" and "No" [2000], II)
     A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts.
5. Theory of Logic / A. Overview of Logic / 2. History of Logic
Was logic a branch of mathematics, or mathematics a branch of logic? [Engelbretsen]
     Full Idea: Nineteenth century logicians debated whether logic should be treated simply as a branch of mathematics, and mathematics could be applied to it, or whether mathematics is a branch of logic, with no mathematics used in formulating logic.
     From: George Engelbretsen (Trees, Terms and Truth [2005], 3)
     A reaction: He cites Boole, De Morgan and Peirce for the first view, and Frege and Russell (and their 'logicism') for the second. The logic for mathematics slowly emerged from doing it, long before it was formalised. Mathematics is the boss?
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
Logical syntax is actually close to surface linguistic form [Engelbretsen]
     Full Idea: The underlying logical syntax of language is close to the surface syntax of ordinary language.
     From: George Engelbretsen (Trees, Terms and Truth [2005], 5)
     A reaction: This is the boast of the Term logicians, in opposition to the strained and unnatural logical forms of predicate logic, which therefore don't give a good account of the way ordinary speakers reason. An attractive programme. 'Terms' are the key.
Propositions can be analysed as pairs of terms glued together by predication [Engelbretsen]
     Full Idea: Sommers's 'tree theory' of predication assumes that propositions can be analysed as pairs of terms joined by some kind of predicational glue.
     From: George Engelbretsen (Trees, Terms and Truth [2005], 2)
     A reaction: This is the basis of Sommers's upgraded Aristotelian logic, known as Term Logic. The idea of reasoning with 'terms', rather than with objects, predicates and quantifiers, seems to me very appealing. I think I reason more about facts than about objects.
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
The sense of a connective comes from primitively obvious rules of inference [Rumfitt]
     Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious.
     From: Ian Rumfitt ("Yes" and "No" [2000], III)
     A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value.
Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt]
     Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table.
     From: Ian Rumfitt ("Yes" and "No" [2000])
     A reaction: This is the standard view which Rumfitt sets out to challenge.
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / c. not
Standard logic only negates sentences, even via negated general terms or predicates [Engelbretsen]
     Full Idea: Standard logic recognises only one kind of negation: sentential negation. Consequently, negation of a general term/predicate always amounts to negation of the entire sentence.
     From: George Engelbretsen (Trees, Terms and Truth [2005], 3)