From a formal logic point of view, an analogy can be two types of argument. One is a valid form of argument, the other is not (i.e. it's fallacious).<p>The valid form is effectively an "argument to generalization", presented via an easier to understand "specialisation", but only keeping within the attributes of the general case.<p>E.g. if arguing X, and both X and Y are special cases of Z, an analogy is an argument on Z, presented through Y.<p>The fallacious variety is then any argument via a specialization Y, which makes use of attributes not present in the general case Z.<p>Given the above, the problem with using an analogy as an argument is as follows:<p>1. People tend to use the fallacious version, neglecting it does not apply to the general case. The response to such an analogy as a form of argument is simply to point out this fact. Unfortunately, people usually tend to focus on why the special attributes of Y are a bad argument in themselves, when in fact they should be ignored.<p>2. Even when people use the valid version, opponents will latch onto attributes, and make a motte-and-bailey attack. The correct defense to that is to reaffirm the validity of the "appeal to generalization" argument, and dismiss any attributes argued by the opponent which do not stem from the generalisation, thus invalidating the attack.<p>This of course is only useful in "discussions", where unlike a debate the aim is not to "win", but to refine arguments in search of better conclusions.<p>In a debate, one can therefore expect an analogy, even a logically valid one, to be a very weak debate strategy given the ease with which it can be attacked by a fallacy and the tediousness of the defense required to refute it, because this leaves the analogist in a position of constant, dry defense against a bombardment of vivid, emotionally charged motte-and-bailey arguments by their opponent, giving them ample opportunity to derail the debate to areas where they will have the higher ground.<p>So, I agree with another poster here. Analogies, particularly valid ones, are good for discussions ("sympathetic audiences"), but bad for debates ("antagonistic audiences").