Oftentimes in philosophy, one is confronted with skeptics, who argue that truth isn’t anything more than a belief one thinks is justified (be it by reason, faith, whim, or “evidence,” [which, the skeptic believes, begs the question of reliability of evidence.]) These skeptics attempt to undermine truth, asserting that, because its basis is exclusively belief, real truth cannot be reached.
But is this skepticism valid?
To attack the claims of these skeptics, one must understand the epistemological roots of truth. First, however, there is something that must be cleared up. Existence is primary. That is to say, existence exists, and it is the fundamental basis of the world. Consciousness is not primary. Though consciousness certainly exists, it cannot determine reality. I cannot simply will a chair blue, or out of existence. To change anything about reality, I must use my consciousness to generate change *using* reality (ie: I can make a chair blue, but I must paint it. I can destroy a chair, but only with tools like explosives.)
Why is this relevant? It helps to assert the axiomatic nature of existence. Existence cannot be denied. To do so, one must use consciousness, logic, and evidence, all things that follow from the primary of existence, to deny it, confirming existence by attempting to deny it. The skeptic must declare that A is not A, that reality is not real, that both he and his ideas, his evidence and proof, is all not real. This is obviously problematic.
Moving to the original point, with reality established, what is truth? Reality is not true, as truth is a concept built presupposing reality. To argue that reality is true is to support an inverted hierarchy of knowledge. Truth, instead, refers to a proposition that is backed by and consistent with reality. The proposition does not contradict reality, and it is logically consistent.
How, then, can truth change over time? It doesn’t. Truth does not change, simply what we believe to be true. “The Earth is flat” could have been believed to be true, as it did not contradict reality. However, as our evidence and understanding of the world and of space grew, the claim increasingly appeared to be false. This is how “truth” evolves over time, when really it is simply our evidence and understanding of it.
Can, then, one consider anything truly true? Yes. Logical truth can exist. Induction is possible. However, scientific truths are slightly different. It is difficult for one to claim that any specific scientific prediction of the future is true. One can easily say “that rock fell.” or “it is the only rational thing to believe the rock will fall when I drop it again.” But being absolutely certain of it falling in the future is not possible, though it is irrational to believe otherwise.
Truth is not based on whims or wishes. It is not “faith.” Truth is objective. If a claim is verifiable confirmed by reality, and it is logically consistent without denying axioms, the claim is true. Truth is achievable. Skepticism is fundamentally irrational.