Re: Hume, induction, and probability

[Kevin S. Van Horn]

Ronald E. Parr wrote:
> More generally, Bayes rule is not an escape from the requirement that we
> reason non-circularly.  If you construct a hypothesis that is
> self-reinforcing, then you have constructed template which can be used to
> justify anything.

What do you mean by a "self-reinforcing" hypothesis?

Note that Bayes' rule is used to *compare* hypotheses, not to examine just a
single hypothesis.  You can't compute a probability that a hypothesis is true
without first specifying the set of alternatives you're considering.  So you can
only have a "self-reinforcing" hypothesis if you refuse to consider any
reasonable alternatives.

But what if the truth isn't among the alternatives you are considering?  One of
the strengths of the Bayesian approach is that it forces you to explicitly
specify the set of alternatives you are considering. This brings hidden
assumptions out into the open,  and makes it easier to step back and question
those assumptions... then perhaps redo your analysis taking into account
additional hypotheses that you didn't consider at first.