As we only have the tools to pursue the truth in that which is relevant, we must consider which tools are most effective in finding truth in the relevant universe. However, before any attempt can be made at discovering truth, there are certain assumptions that must be made.
1: Reality exists independently of myself.
Namely, my existence does not define reality. This is a bit of a leap of faith to make, but without making it there's no truth to discover really, other than to try to figure out my own thought processes.
2: That which I observe exists independent to myself.
Somewhat of an extension to assumption 1, but still quite important. If I'm a brain in a jar or some thoughts floating on the aether, then I do not have access to the truth, even if it is out there. Because the truth then is not relevant given that I can never hope to find it.
3: Truth remains truth regardless of time passed.
That which is true today must be true tomorrow if the pursuit of truth is to have meaning. Note that when I say that, I don't mean that a statement made today will always be true, but that it will always be true relative to when it was said. Saying something like “I saw a bird today” will be true or false on any given day, but it's truth value on that day will not change. If for example, birds could be suddenly erased from the timestream entirely, well nothing would be true for long really. So I assume constant values of truth.
4: The universe changes in an ordered manner.
An extension to 3, things have to change in a causal way or else truth becomes pointless. I assume that the universe follows certain laws, because if it does not truth exists only in instants. If what is a fish today is a bicycle tomorrow, then trying to find truth will be meaningless, and my own existence tenuous.
With those assumptions in place, we can proceed. By assumption 4, the universe must follow certain laws. That means that a great deal of truth can be found by investigating those laws. Perhaps those laws too may change, but they'd have to change in an ordered manner as well, subject to laws above themselves.
Which of course leads us to science.
And in the interest of not flooding further, I'll cut it off there. Any questions would be appreciated, and I'm sorry bout the walls of text :P
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