Central Problems of Philosophy

Prof. Stephen Schiffer

Fall `98


Handout 5


  1. Knowledge by induction (if we have any!) is knowledge that is directly or indirectly based on knowledge of regularities that have held in the past; i.e., knowledge that evidently presupposes PUN (= the principle of the uniformity of nature).
  2. A proposition p is self-evident if merely believing p is sufficient for knowing p; i.e. (nearly enough) merely believing p entails that p is true.
  3. Past futures have resembled past pasts.
  4. PUN

    So, the future will resemble the pastói.e., PUN.

  5. Humeís argument:
    1. One has knowledge by induction only if one knows PUN.
    2. One knows PUN only if (a) PUN is a necessary truth known a priori, (b) PUN is a contingent truth that is self-evident, or (c) PUN is a contingent truth known by induction.
    3. Not (a): itís perfectly possible that the future wonít resemble the past.
    4. Not (b): believing PUN certainly doesnít secure its own truth.
    5. Not (c): any attempt to establish PUN by induction must be "going in a circle, and taking that for granted, which is the very point in question" (Hume).
    6. Therefore, no one has knowledge by induction.