Reasoning by analogy is at the heart of what has been called "the outside view" as opposed to "the inside view" (in the context of, e.g., trying to work out how long some task is going to take). Eliezer is on record as being an advocate of the outside view. The key question, I think, is how deep are the similarities you're appealing to. Unfortunately, that's often controversial.

(So: I agree with Robin's first comment here.)