The first characteristic or attribute of the truth that comes to mind is that the truth corresponds with the real, physical world independent of our personal mental perspective in a way that can be verified by others. The picture appended to this post contains a photograph juxtaposed with a sketch of roughly the same view--Trophy Point at West Point, New York. The sketch was made by a friend, and as soon as I saw it, I knew it corresponded well with the actual view. Later, when I had the chance to get an actual photograph of the same general view, I was struck by the accuracy of the sketch. These pieces of art rest next to each other in my home. For me, they represent the correspondence dimension of truth--the correspondence of what our minds "see" with what is actually, physically "there". Independent evidence that such a correspondence exists is evidence for the truth of a proposition or theory. Likewise, evidence that such a correspondence DOES NOT exist is evidence that a proposition or theory is false.
Of course, there's a catch, and it's one we've been aware of at least since the "Allegory of the Cave"--the famous passage in the Republic where Plato depicts our individual perception as imperfect glimpses of shadows cast by some reality that we cannot see directly. Modern cognitive science concurs with Plato's intuition--Daniel Kahneman's Thinking Fast and Slow captures the tension between our visceral, emotional response to the world we perceive and our more deliberative, rational response to the same phenomena. The lesson of both Plato's metaphor and Kahneman's research is that we should be skeptical of putting too much confidence in our individual perceptions of what is right and true. For that reason, we should seek independent verification of the correspondence dimension of truth.
So if truth is comprised by correspondence with the external world, but our individual ability to perceive that correspondence is imperfect, how can we determine if something is true? After all, we said last night that it cannot be a matter of what is agreeable to one or more of us. While mere consensus is not sufficient to establish truth, there is clearly some additional measure of credibility that comes from having additional verification by independent observers. Another aspect of truth that can reinforce correspondence is the degree to which a perception is coherent with other perceptions held by the same individual and by others. It seems then, that we have identified some conditions of truth that are necessary: correspondence with the physical world outside of our individual perceptions, the coherence of a single perception with some broader set of perceptions, and the independent verification of that correspondence and coherence by other observers. Yet another dimension of independent verification is the ability to predict: we have more faith that a description of physical processes is "true" when that description can be used to predict future states.
So we have identified four attributes of truth. We may not have the luxury of having all four present in every case. Clearly these attributes reinforce one another. Perhaps we can say that all four together create strong evidence for the truth of a proposition or theory. And some subsets of the four attributes create varying degrees of confidence in the truth of a proposition or theory. That is where we will leave our discussion of the criteria for truth, at least for tonight.