Combining Philosophers

Ideas for Stilpo, Thomas Jefferson and Gottlob Frege

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6 ideas

5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
The truth of an axiom must be independently recognisable [Frege]
     Full Idea: It is part of the concept of an axiom that it can be recognised as true independently of other truths.
     From: Gottlob Frege (On Euclidean Geometry [1900], 183/168), quoted by Tyler Burge - Frege on Knowing the Foundations 4
     A reaction: Frege thinks the axioms of arithmetic all reside in logic.
To understand axioms you must grasp their logical power and priority [Frege, by Burge]
     Full Idea: Understanding the axioms depends not only on understanding Frege's elucidatory remarks about the interpretation of his symbols, but also on understanding their logical structure - their power to entail other truths, and their reason-giving priority.
     From: report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884], 4) by Tyler Burge - Frege on Knowing the Foundations 4
     A reaction: This is a distinctively Burgean spin put on what Frege has to say about axioms, but I like it, and it seems well enough supported in Frege's writings (e.g. 1914).
Tracing inference backwards closes in on a small set of axioms and postulates [Frege]
     Full Idea: We can trace the chains of inference backwards, …and the circle of theorems closes in more and more. ..We must eventually come to an end by arriving at truths can cannot be inferred, …which are the axioms and postulates.
     From: Gottlob Frege (Logic in Mathematics [1914], p.204)
     A reaction: The rival (more modern) view is that that all theorems are equal in status, and axioms are selected for convenience.
The essence of mathematics is the kernel of primitive truths on which it rests [Frege]
     Full Idea: Science must endeavour to make the circle of unprovable primitive truths as small as possible, for the whole of mathematics is contained in this kernel. The essence of mathematics has to be defined by this kernel of truths.
     From: Gottlob Frege (Logic in Mathematics [1914], p.204-5)
     A reaction: [compressed] I will make use of this thought, by arguing that mathematics may be 'explained' by this kernel.
A truth can be an axiom in one system and not in another [Frege]
     Full Idea: It is possible for a truth to be an axiom in one system and not in another.
     From: Gottlob Frege (Logic in Mathematics [1914], p.205)
     A reaction: Frege aspired to one huge single system, so this is a begrudging concession, one which modern thinkers would probably take for granted.
Axioms are truths which cannot be doubted, and for which no proof is needed [Frege]
     Full Idea: The axioms are theorems, but truths for which no proof can be given in our system, and no proof is needed. It follows from this that there are no false axioms, and we cannot accept a thought as an axiom if we are in doubt about its truth.
     From: Gottlob Frege (Logic in Mathematics [1914], p.205)
     A reaction: He struggles to be as objective as possible, but has to concede that whether we can 'doubt' the axiom is one of the criteria.