[candu]

Aside from other good techniques mentioned here (have a mediator who is empowered to force a "disagree and commit" resolution, use collective or impersonal language), one useful technique is to focus not on where you disagree, but on where you agree.

For instance: in debugging, even if you disagree on what to try, you probably still agree on what's happening, and that you want to fix it. This changes your task from proving who's right to solving the problem together. It also focuses attention on what you know / can observe to be true.