There are whole categories of propositions that can be disproven: x●~x is not always trivially obvious.
There are also propositions that are provable, unless you buy the strong Cartesian skeptic's position.

The rest fall into three broad categories:
With weak evidence against a proposition:
Provisionally against

With no compelling evidence for or against a proposition:
Provisionally neutral
and
With weak evidence for a proposition:
Provisionally for

If it turns out that the evidence in any case above is false, belief in the proposition should probably shift toward the center.