Honest discussions or debates have one purpose: to illuminate a subject with facts and theories which relate facts to eachother, and perhaps to persuade. Dishonest debates or arguments are really just fights with words, and of interest only to litigators and politicians.
Fallacious arguments of the false assumption type are used in both: in the former by accident or out of ignorance, and in the latter as a tactical trick (eg "If the glove don't fit, you must acquit.").
When questions are posed in that manner, they are known as loaded questions. They are "loaded" with an effort to seek your acquiescence to an unspoken assumption. (The classic is "When did you stop beating your wife?") The correct response to questions with hidden assumptions is to point that out, and to challenge the hidden assumption. Otherwise, you will fall into a trap.
When engaging on an issue, always examine the other guy's assumptions first, because a topic can go nowhere with fallacious assumptions, and there can be no constructive discussion if you do not accept the other guy's premise. In that case, you must address the premise first, backing up before you can move forward.
Here are some simple examples of fallacious assumptions. Usually, in arguments, the assumptions are unstated, "assumed." It's better to state them first just as one lists one's "givens" in geometry proofs. Sometimes, just addressing the assumptions clears everything up.
John at Powerline: You Can Prove Anything If You Make the Right Assumptions. Certainly true, if one is engaging in dishonest or tendentious debate.
(I am aware that I am not discussing the huge and important topic of unconscious assumptions, but that is more about psychology than logical debate.)
