I think analogy is useful in an argument for a few reasons: 1. It can reduce the problem space to the factors which the parties see as important. 2. It can un

I think analogy is useful in an argument for a few reasons: 1. It can reduce the problem space to the factors which the parties see as important. 2. It can uncover differences of opinion as to which factors are deemed important to the problem space. ie: "yeah, but your analogy discounts x!". Of course, analogies can be used in bad faith as rhetorical tools to win an argument on grounds other than it's merits, and that is the real problem with them.