In The Crucible, why are the voices of reason, John Proctor and Rebecca Nurse, not listened to by the people of Salem?

I think that this becomes the central issue of the drama. 
In the end, part of what makes Miller's work so compelling is that the hysteria that
sweeps through the town precludes reason from being embraced.  Miller argues that this
is by design of those in the position of power who benefits from such hysterial.  Those
like Abigail Williams or Thomas Putnam are in the position of political power and wield
that influence in order to achieve their own self interest or consolidate their own
power.  There is a deliberate intention to mislead and in the haze of confusion, those
in the direct position of power benefit greatly:

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In the girls' initial accusations and the frenzy
that ensues, Miller demonstrates how peer pressure can lead individuals into taking part
in actions which they know are wrong. And in the community's reaction to these
accusations, he shows how easily stories can be taken out of context—and how people are
blamed for crimes they haven't
committed.

It is precisely
this chaos, where guilt and innocence are confused, that allows those in the position of
power to benefit.  This means that the voices of reason need to be drowned out so that
those in political power can continue their own
ways.