To believe especially on uncertain or tentative grounds
Conjecture
Hypothecate
Hypothesise
Hypothesize
Speculate
Suppose
Theorise
Anticipate
Expect
Construct
Formulate
Reconstruct
Retrace
Explicate
Develop
Theorizer
Theory
Construct a theory about
Reason
Theorization
Galileo theorized the motion of the stars
Form or construct theories
He thinks and theorizes all day