Sentence:  It is tempting to <WSD>speculate</WSD> about the incentives or compulsions that might explain why anyone would take to the skies in [the] basket [of a balloon]: perhaps out of a desire to escape the gravity of this world or to get a preview of the next; [...]. 
Meaning of the word marked with <WSD> tags:  To make an inference based on inconclusive evidence; to surmise or conjecture.