  The anthropic principle has been proposed as an explanation for the observed
value of the cosmological constant. Here we revisit this proposal by allowing
for variation between universes in the amplitude of the scale-invariant
primordial cosmological density perturbations. We derive a priori probability
distributions for this amplitude from toy inflationary models in which the
parameter of the inflaton potential is smoothly distributed over possible
universes. We find that for such probability distributions, the likelihood that
we live in a typical, anthropically-allowed universe is generally quite small.
