Truth.

How are we supposed to know what's true?

Don't come up with a view, find everybody who agrees with it, and then say, "Look at this, I must be right."

Start off by saying, "Who do I trust?"

On global warming, for example, I happen to trust climate experts, world academies of science, Nobel laureates, and certain science journalists. You have to decide who you trust before you decide what to believe.

excerpted from Wired magazine, September 2010.
Interview with Simon Singh, pp. 112-115.
The Truth Is Out There
by Robert Capps.