1. A simple statement about your opinion. Direct.
2. Possible, but not common. One way this could be used: I come in, and say to a group of you, "Hey! I here someone here thinks I'm wrong. Who is it? Who is saying I"m wrong?" and you say, "I say you're wrong!" (Not very likely, is it?)
3. It's conditional.
Me: If I asked your opinion about what I just said, what would you say?
You: I would say you are wrong.
Me: What would you say if I told you that the H1N1 vaccine is a secret plot by the world's governments to reduce world overpopulation?
You: I would say you are wrong (and probably a bit crazy too).
Student or Learner