Because without scientific curiosity we would
not have scientific discovery.
Because democracy depends on an informed public
(because, in principle, the public are needed to make decisions
directly or indirectly);
Because an unquestioning individual can be hookwinked
and manipulated;
Because our society is constructed of a set of
assumptions built on each other
and on shifting conditions, and only by constant
inspection can this framework of assumptions and beliefs
be maintained in a sufficiently consistent state for
us to stay out of serious trouble.