The Many Assumptions of SETI

Some folks think that that concluding there are no intelligent aliens because we can't hear any radio signals is like concluding there are no intelligent aliens because we can't find any good Thai restaurants beyond the asteroid belt. The assumptions we're making are many and difficult to identify, given our provincial experience of the universe, and yet we must make assumptions if we're even going to get started. Here's a brief post about this problem, linking to a more in-depth discussion at Centauri Dreams. I share this concern and mentioned it before in my post about how to find von Neumann probes.