"We are being visited."

[Digital_Trucker]

Originally Posted by Letum

The same way we get all good knowledge.
We look at the refutable evidence for the hypothesis and use various tools of
reasoning to decide if the evidence makes the hypothesis more than likely.

Either:
A) There will be enough evidence for us to reason that the hypothesis is
more likely than not. In this case we can say that we know the hypothesis
to be true to some degree of certainty, however small.
or
B) There will not be enough evidence for us to reason that the hypothesis
is more likely than not. In this case we can say that we know the
hypothesis to be false to some degree of certainty, however small.

I can't imagine a situation in which the evidence we have makes it
impossible to reason one way or the other. Only refusal to do so would
result in a 'I don't know' answer.

In other words, you make an educated guess.