Assume, assume, assume
Consider, imagine, visualize
What if
Probably
Must have
Could have
Should have
May have
Scientists are taught to write like that. It's a reflection of the uncertainty of the profession. No matter how carefully thought out the hypotheses and interpretation of the data, it is always possible for someone to come along with a better hypothesis or interpretation. In the scientific literature, about the only time you will see a scientists state anything with certainty is when they are describing their direct observations.
"Following treatment with the compound ABN342394, expression of caspases 3 and 8 increased; however, the cells did not enter apoptosis. We believe that the inhibition of apoptosis results from the binding of ABN342394 to the caspase active site." The second sentence leaves open the possibility of a different interpretation.
That may hold true for most of science. Unfortunately, the fossil record, the ToE, and origins seem to be exempt from other interpretations.
The *evolution is a fact* crowd won't hear of it.