What is the Definition of Truth?

Truth
If someone says that there is no truth, then there's at least one thing that's true: the statement they just uttered that there is no truth. It's one of those awkward situations for a person making a claim, because there's no way their claim can be true. If it's true, it's false, and if it's false, it's false. Obviously, if the statement "There is no truth" is false, then it's false. But even if it's true that there is no truth, then it's also false, because that becomes a true statement, which nullifies it.

 
Pragmatic Theory of Truth
Some of us want to define the truth for ourselves. One notion of truth is called the pragmatic theory of truth. It argues that the truth is simply what works. How many times have you heard someone say, “Your Christianity may work great for you, but it doesn’t work for me”. It’s a very practical approach! If it doesn’t work, it’s not true. But what about death? It’s definitely not practical, yet it is definitely true! And what about things that are definitely not true, but are practical, like a successful lie? The pragmatic theory does not lead us to truth.

Empiricist Theory of Truth
The empiricist theory of truth says that the truth is whatever can be sensed. Experience is the main factor. How many times have you heard someone say, “I know it is true because I experienced it myself!” but this also falls short of the mark. Some of us will taste an orange and say that it is sweet, while others will taste the same orange and say it is bitter. Who is telling the truth? Sensory experience is too personal to be trustworthy!

Emotivist Theory of Truth
The emotivist theory of truth says that the truth is based on what we feel! How many times have you leaned on feelings to figure out if something was true? How many times have you struggled to convince yourself that what you are feeling isn’t really true, just the way you feel that day? But we all know someone who holds irrational fears, and these are obviously not true! And what if I show you a handful of paperclips? You aren’t really going to feel one way or the other about them, but it will still be true that I am holding four paperclips! This theory is not a great way to establish truth!

Correspondence Theory of Truth
To many, the concept of truth is deep, esoteric and indefinable. Let me give you a definition in one syllables. It's from Aristotle, I think. If you say "It is," and it is, or "It is not," and it is not, then you speak truth. If you say "It is," and it is not, or "It is not," and it is, then you don't speak truth. This is called correspondence, in other words, a thing is true if and only if it actually corresponds to what is really there. Truth, therefore is not determined by opinion or belief. Believing something to be so doesn't make it so. It is not true merely to me. It might be true to me and still entirely false.

 
Truth Must Correspond!

It's absolutely necessary for us to use rationality to discern truth from error in the physical realm, it is just as important to use rationality to discern truth from error in the spiritual and moral realm. The problem is that when we employ rationality and critical thinking to the physical realm we are considered sane and prudent, but when we apply rationality to the area of moral and spiritual truth we are considered intolerant.

Tolerance is a word that applies to how we treat people, not how we treat ideas. We are to be tolerant of people, but we are not to be tolerant of ideas. What do I mean by not tolerating ideas? We are to address ideas in the same way that we address any other observations that we make in this world. We look at this world and make observations and we use rationality to thread through those things and be critical of our observations, to try and discern right from wrong, truth from falsehood. When it comes to religion and when it comes to moral and spiritual issues, anything dealing with the immaterial realm, we are to be just as assiduous in applying rational, critical thinking to the process of separating truth from error as we are in the material, physical, amoral realm. Rationality is how you treat ideas.