Argument by analogy

A 95 year old, rather wealthy, man goes to see his doctor and says "I can't believe it, I got my 25 year old girlfriend pregnant."

The doc says, "let me tell you a story. There was once a man who went bear hunting with his umbrella. He happened upon a giant bear whereupon he shot the bear dead."

The old replies," that's impossible, somebody else shot that bear."

The doc says,"my point exactly."