How to convince my supervisor that he is wrong? I do not have any particular situation at hand but I am about to start in a new short-term (research assistant) position. The thing is, I will be working on a topic that is very controversial. There are papers (appearing in top journals) explaining how my supervisors and their colleagues got it all wrong. On the other hand, there are reviews (in top journals also), summarizing how many important insights have been learned, and how things are progressing very nicely. It appears to be a kind of battlefield.

I have not yet started in the position, but I have been reading several articles about the research topic. I already know that I will disagree with my supervisor about many things. There will probably be difficult conversations. If we get everything right, maybe we could resolve some of the major issues, by discussing both perspectives thoroughly.

I think I will need very good negotiation skills. If we have exact opposite views with my supervisor, I must do what he wants, but I also want to do what I want. I want us to succeed. How do I prepare for this? How does one convince her supervisor that he is wrong about something? Of course, I will be wrong many times as well. So I should also think how to quickly realize that I am wrong about something.
The whole point of scientific debate is to refine our knowledge. Go into the discussion with a mentality to learn, not to win. Keeping this in mind will help you keep the discussion not adversarial and not emotional. On unresolved disagreements, try to find a way to falsify either hypothesis. If it is not possible, consider that which option is correct is probably not that important.

Listen to what they have to say about the criticisms, maybe they disagree with them, maybe they agree (and maybe even that is why the brought new people in). Probably, it is somewhere in the middle.

If (or when) your relationship is good, and you have a good understanding of their position, you can even propose playing devil's advocate.

Of course, I am assuming that they are decent people and not tyrannic professors. You should assume the same until proven otherwise (and if so, consider if you want to shut up and obey, or walk away).