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Re: The "two child solution"



"I ask the straightforward question: How can knowledge
of a fragmentary *a posteriori* nature affect the *a
priori* probability of either person having two sons?"
<end quote>
I respond - by having "=E0 posteriori" knowledge, we are limiting that
portion of the "=E0 priori" universe that we consider. If we choose to
exclude two DIFFERENT portions of the universe, then we will get two
different answers to the same question (with different conditions)

That is correct, of course, but the question was asked
rhetorically. *A priori* considerations have no valid
logical role *a posteriori*. Former possible universes
are excluded from consideration on more than merely
philosophical grounds.

Of course there are circumstances in which *a priori*
reasoning may play a useful role *a posteriori*. For
example, consider the fellow who opens Schrodinger's
cat's ordeal chamber. He must decide whether or not to
take a deep breath as he does so. He *could* do the
calculation to decide on the desirability of that
action, and the *a priori* probability would play a
proper role in risk assessment. On the other hand, it
might just be prudent not to do so.

Leigh