speculative.
This is how science works.
*edit, for the record, for me, as a postdoc, a hypothesis, while more structured than mere speculation, is still an unproven explanation that requires rigorous testing and peer review before it can be considered established scientific knowledge, and thus remains speculative.
You’re a postdoc and you don’t think this is obvious? That’s what follows a hypothesis in the scientific process.
Make an observation or ask a question.
Gather background information.
Create a hypothesis. (You are here)
Create a prediction and perform a test.
Analyze the results and draw a conclusion.
Share the conclusion or decide what question to ask next: Document the results of your experiment.