One reason we can't tell if there's absolute truth is that there is no way to determine if different people's definitions of something are the same. When I see white, it might actually be what you'd define as white. My blue might be your green. When I say "green," how can we be sure we're thinking of the same color? We could actually speak different languages, but what I'm writing makes sense in both, even though the meanings are different. However, there is absolute truth in math. If you take two apples, then take two more, you will always have four total. Now, it's just a matter of if you can actually tell if you have two pairs of two apples each. If you actually have four apples, you have four, two pairs of two, no getting around it.
Except, math isn't immune to the issue of the way we perceive. Just as we cannot be sure what each being defines as "Green" or "Blue" we also cannot be sure if everyone defines numbers in the same way. For example, If you haven't been taught the standard counting system (1,2,3), then you might believe that when I say that there are two apples that there are actually twice as many apples as I have told to you.
I'm going to tell an example.
"I have a Pool Table in my basement."
I will also say that for this example, the following things are truths:
•A pool table is a table in which people are able to play pool on.
•We both define pool to be the same game.
•You have no reason to believe that I wouldn't have a pool table. You actually know that I am a skilled pool player, so a pool table is a reasonable thing for me to own.
Now- If someone asks you tomorrow, "Does Norm have a pool table in his basement?"
What is the answer?
You have been taught that the pool table exists, and it is located in my basement, just like how you have been taught the definitions of each color. To you, the following information is truth: "Norm has a pool table in his basement"
So when asked that, you would probably say "Yes, he does" or "I believe he does"
Not a big deal right? Well, let's say that I don't have a pool table. If the same person were to ask me if I had a pool table in my basement I'd say no. Well here's the tricky part.
"Yes, Norm has a pool table in his basement" "No, Norm does not have a pool table in his basement"
Both of these pieces of information are both true and false depending on where they are placed. In my mind, the second piece of information is truth. To you, the first piece of information is truth. If a stranger went up to you and let's say you have no reason to believe them. They tell you that I in fact do not have a pool table in my basement. Did they just lie to you? If not, did they lie to you in your perception? He both lied and didn't lie to you depending on who's to judge.
My point is that there is that absolute truth cannot exist as long as more than one being is able to process information. For some giggles, try replacing the pool table in my basement to something more serious like the existence of a religious being to see how serious this can get =)
None.