term:

Speculate

speculate vb

-lat·ed
-lat·ing
vi
1 : to theorize on the basis of insufficient evidence NOTE: A jury is not permitted to speculate on a matter about which insufficient evidence has been presented in reaching its verdict.
2 : to assume a business risk in hope of gain
;esp
: to buy or sell in expectation of profiting from market fluctuations
vt
: to take to be true on the basis of insufficient evidence
spec·u·la·tor [-lā-tər]
n

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.