logical/rhetorical fallacy

Is there a name for the logical fallacy one often sees in debates that goes something like this: “You are for A, therefore you must believe B, C,D (or you must also be one of those people that often believe B,C,D who also believe A).”

Get my drift?

I don’t know the answer to your question but more than likely it resides here:
http://www.geocities.com/phineasbg/kirklogic.html

I’m afraid I can’t answer your question, but here are some good sites for exploring logical fallacies:

Fallacies
Formal Logic and Logical Fallacies
The Atheism Web Logic & Fallacies
The logical Fallacies Index
The Logical Fallacies

There are a number of fallacies that fit this description, but the most general would be a non sequitur, meaning “it does not follow”. The only place where B always follows A is in the Roman alphabet.

It could also be an ad hoc fallacy, which is an attempt to give an after-the-fact explanation that may not be supported by evidence.

More fallacies.

The name of this fallacy is stereotyping. Basically, you’re stereotyping whenever you assume that what’s true for a proportion of the group is true for every member of the group.

I’m not 100% sure that your second example is fallacious. If those who believe A often also believe B, C, and D, then if you meet someone who believes A, there’s a good chance that they also believe B, C, and D. Just don’t assume that they must unless they tell you.