"What you need to look for is a track record of intellectual honesty. Let me therefore propose 10 signs of intellectual honesty." However, one note of caution I would put in there is that these points are valid only if the argument is well-reasoned and grounded to begin with. If your argument is grounded in factual relativism, that's intellectually dishonest too.
Andrew, read this. Note that the person writing this is a long-time Microsoft consultant. "The common criticisms that dynamic languages aren't understood by most developers and don't work for large projects just don't hold water. The lack of compiler (and some dynamic languages have compilers) is a non-issue to. The normal testing the compler does (and that's the right way to think of it) is superceded by the better overall test coverage you can achieve. And while they may not be as fast as C# and Java (which weren't as fast at C++ when they started), they scale fine if you've app's architecture is solid (and a bad architecture will cripple scaling no matter what language you use)."