"Can someone initially propose a hypothesis without evidence?"

No serious historian invents hypotheses from nothing.

Usually there is some observation that motivates it.

Example

Observation:

industrialization expanded,

legal reforms occurred.

Hypothesis:

Perhaps these developments were connected.

That initial observation is already a kind of evidence.

So "without evidence" is too strong.

More accurately:

A hypothesis usually begins from preliminary observations, but it still requires further evidence before being accepted.