Brow-beating

A Di-LemmaA reader with the monometopian name of OneBrow wrote in comment to an earlier post: 

As traditionally presented, the argument from motion rarely lists all the assumptions at the beginning. Assumptions such as "motion must be externally activated from potential" and "motion can not be in an infinite chain" get worked into the argument, often by declaring them to be obvious (the very notion of being an assumption). By then end of the argument, there are a fairly good-sized number of assumptions (each distinct argument having its distinct subset).

Now, in mathematics, a lemma is a proven statement used as a step in the proof of a bigger theorem.  There is no formal difference between a lemma and a theorem -- both follow the same rules of proof -- but there is a material difference.  The main interest centers on the matter of the theorem, while the matter of the lemma is of little interest in itself at the moment.  In the same manner a carpenter may use a hammer in the construction of a cabinet without any imputation that the hammer is simply assumed, and not itself constructed.
Read more »