Supplement to Defeasible Reasoning

Popper Functions

A Popper function is a function from pairs of propositions to real numbers that satisfies the following conditions:

  1. For some D, E, P[D|E] ≠ 1.
  2. P[A|A] = 1.
  3. P[A|(C & B)] = P[A|(B & C)].
  4. P[(B & A)|C] = P[(A & B)|C].
  5. P[A|B] + PA|B] = 1, or P[C|B] = 1.
  6. P[(A & B)|C] = P[A|(B & C)] × P[B|C].

Copyright © 2013 by
Robert Koons <koons@mail.utexas.edu>

Open access to the SEP is made possible by a world-wide funding initiative.
Please Read How You Can Help Keep the Encyclopedia Free