speculative proposition, n.All

A Speculative proposition (n.) gives ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠thinking a counter-thrust: setting out from the subject as firm ground, it finds the subject has passed over into the predicate and been sublated.