Good stuff from Skeptico on the problems of arguing by analogy:
Here’s the thing – if I had to argue that racism is bad, I wouldn’t think of an analog to racism that we all agree is bad, and say “hey, racism’s the same”. No, I would explain why racism is bad. With perhaps some facts, citations, logic, evidence. Of course, I could do that because racism is, actually, bad, and so the facts logic and evidence are there to support the statement. Woos don’t have anything to back up their position, so analogy is often all they have.
I guess it’s a form of straw man, but I’d never thought of it this way before. The common example is: religion is like race, therefore criticising someone’s faith is wrong.
When someone argues by analogy, you can be pretty sure it’s because they don’t have any facts, evidence or logic to support their position. And all you have to do to debunk their argument, is find the flaw in the analogy.
In ways that are pertinent to the argument, religion isn’t like race. I guess analogy is useful when supporting a point, but it’s a weak way of making one.