Sorry, but no science is possible without data, indeed you might even say that science without data is just philosophy, but maybe that's too mean? ;-)
So science begins with observations / data / facts and attempts to explain what it sees -- what, how, why, etc.
Brain-storming & speculations first -- let's make a list of what it might be, then whittle the list down by throwing out what's impossible and restating what's possible as falsifiable hypotheses, etc., etc.
reasonisfaith: "And the identification of an hypothesis involves the context of a preexisting belief system."
In a genuine brainstorming speculation phase any and all potential hypotheses get listed & evaluated, including testing of ones which look promising.
Indeed the stimulus for the process is very often precisely because a "preexisting belief system" (i.e., scientific theory) was challenged by new data.
And the general truth is that scientists live & hope for such situations because its only time they truly get to do their science "thing".
A man referred to as the father of empirical science, Sir Francis Bacon, is quoted as follows:
“Man prefers to believe that which he prefers to be true.”
Not what’s true, but what he prefers to be true.
This is why we have the double blind aspect in research.