The first clause of the amendment (A well regulated militia being necessary ...a free state") is an introductory clause, not a defining part of the law; it explains a priori conditions for a decision but are not part of the decision, logically. In the sentence "Because people need fresh air and exercise, I will never force you to take the schoolbus rather than walk to school." you would scarcely conclude that there was no other possible reason for permitting (x) to walk to school; nor would you conclude that the speaker was decreeing that people needed fresh air and exercise; neither would you interpret it to mean that the permission would only hold true as long as people were thought to. The explanatory context is an observation preceding a conclusion, but the conclusion stands, as a legal mandate, all on its own: the right to bear arms shall not be infringed. There is some implication of context but it is in no way construable as a part of the legal conclusion.

I have no desire to bear arms, and never have -- but I sure as hell don't want that right compromised by someone who can't even understand plain English!!

A