I caught the end of an interview with him about this on NPR yesterday. I'm glad I didn't call in, because it turns out that I actually agree with what he is saying. Just in a slightly different way.

The Constitution does not grant any right, it merely highlights rights. It states right in the preamble that the Constitution is not a comprehensive list of rights, and is only highlighting important ones. If 99% of America decided to abolish the Constitution tomorrow, my rights, and my willingness to defend them, would not change one bit. The Constitution only serves as a focus to the issue of rights.

There is a much larger conversation about establishing documents in order to enable lawful actions like court cases, and to get public opinion at least in the same arena of thought, but I'm not sure this is the thread to discuss that part.