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12. Knowledge Sources / A. A Priori Knowledge / 6. A Priori from Reason

[a priori knowledge as the produce of pure reason]

7 ideas
To achieve pure knowledge, we must get rid of the body and contemplate things with the soul [Plato]
     Full Idea: We are convinced that if we are ever to have pure knowledge of anything, we must get rid of the body and contemplate things by themselves with the soul by itself.
     From: Plato (Phaedo [c.382 BCE], 066c)
     A reaction: This seems to be the original ideal which motivates the devotion to a priori knowledge - that it will lead to a 'pure' knowledge, which in Plato's case will be eternal and necessary knowledge, like taking lessons from the gods. Wrong.
I aim to find the principles and causes of everything, using the seeds within my mind [Descartes]
     Full Idea: I have tried to find in general the principles or first causes of everything which is or which may be in the world, ..without taking them from any other source than from certain seeds of truth which are naturally in our minds.
     From: René Descartes (A Discourse on Method [1637], §6.64)
Reason contains within itself certain underived concepts and principles [Kant]
     Full Idea: Reason itself contains the origin of certain concepts and principles, which it derives neither from the senses nor from the understanding.
     From: Immanuel Kant (Critique of Pure Reason [1781], B355/A299)
     A reaction: You might say that these principles are known 'by the natural light' rather than being innate, but if they are not even 'derived from the understanding', that seems to leave them innate, which is a classic hallmark of a rationalist philosopher.
In long mathematical proofs we can't remember the original a priori basis [Kitcher]
     Full Idea: When we follow long mathematical proofs we lose our a priori warrants for their beginnings.
     From: Philip Kitcher (The Nature of Mathematical Knowledge [1984], 02.2)
     A reaction: Kitcher says Descartes complains about this problem several times in his 'Regulae'. The problem runs even deeper into all reasoning, if you become sceptical about memory. You have to remember step 1 when you do step 2.
Understanding needs a priori commitment [Horwich]
     Full Idea: Understanding is itself based on a priori commitment.
     From: Paul Horwich (Stipulation, Meaning and Apriority [2000], §12)
     A reaction: This sounds plausible, but needs more justification than Horwich offers. This is the sort of New Rationalist idea I associate with Bonjour. The crucial feature of the New lot is, I take it, their fallibilism. All understanding is provisional.
Lots of propositions are default reasonable, but the a priori ones are empirically indefeasible [Field,H]
     Full Idea: Propositions such as 'People usually tell the truth' seem to count as default reasonable, but it is odd to count them as a priori. Empirical indefeasibility seems the obvious way to distinguish those default reasonable propositions that are a priori.
     From: Hartry Field (Apriority as an Evaluative Notion [2000], 1)
     A reaction: Sounds reasonable, but it would mean that all the uniformities of nature would then count as a priori. 'Every physical object exerts gravity' probably has no counterexamples, but doesn't seem a priori (even if it is necessary). See Idea 9164.
Aristotelians dislike the idea of a priori judgements from pure reason [Mares]
     Full Idea: Aristotelians tend to eschew talk about a special faculty of pure reason that is responsible for all of our a priori judgements.
     From: Edwin D. Mares (A Priori [2011], 08.9)
     A reaction: He is invoking Carrie Jenkins's idea that the a priori is knowledge of relations between concepts which have been derived from experience. Nice idea. We thus have an empirical a priori, integrated into the natural world. Abstraction must be involved.