In his posthumously published On Certainty
Wittgenstein discusses, amongst other things, the nature
of knowledge, belief and certainty.
He stresses the holistic nature of beliefs, saying at section 141,
for example, "That when we first believe anything, what we
believe is not a single proposition, it is a whole system of
propositions. (Light dawns gradually over the whole.)"
Relatedly, despite appearances, we seldom learn new propositions
piecemeal; rather we acquire propositional knowledge in holistic clusters.
And Wittgenstein illustrates this with the following example at section 143:
"I am told, for example, that someone once climbed this mountain
many years ago. Do I always enquire into the reliabiliy of the teller
of the story, and whether the mountain did exist years ago?
A child learns there are reliable and unreliable informants much later
than it learns facts which are told it. It doesn't
learn at all that that mountain has existed for a long time:
that is, the question whether it is so doesn't arise at all. It swallows
this consequence down, so to speak, together with what it learns."