This paper points out that there exists a relationship between the pri
nciple of Maximal Entropy (ME) in probability theory and the principle
of minimal Specificity (mS) in possibility theory via consistent tran
sformations on sets of probability and possibility distributions. By u
sing these transformations, the paper investigates the possibilities t
o apply methods of probabilistic logic for possibility knowledge bases
and conversely, reasoning methods of possibilistic logic for probabil
ity knowledge bases.