The 'Atthasālinī' (Book II, Part IX, Ch. III, 259) states about doubt:
Here doubt means exclusion from the cure (of knowledge).
Or, one investigating the intrinsic nature
by means of it suffers pain and fatigue (kicchati)- -thus it is doubt.
It has shifting about as characteristic,
mental wavering as function,
indecision or uncertainty in grasp as manifestation,
unsystematic thought as proximate cause,
and it should be regarded as a danger to attainment.
Doubt is different from wrong view (ditthi). When there is ditthi one clings,
for example, to the view that phenomena are permanent or that they are self.
When vicikiccha, doubt, arises, one wonders whether the mind is different
from the body or not, whether phenomena are permanent or impermanent.
There is no other way to eradicate doubt but by developing of paññā which
sees realities as they are. People who have doubts about the Buddha and his
teachings may think that doubt can be cured by studying historical facts. They
want to find out more details about the time the Buddha lived and about the
places where he moved about; they want to know the exact time the texts
were written down. They cannot be cured of their doubt by studying historical
events; this does not lead to the goal of the Buddha's teachings which is the
eradication of defilements.