I'm not sure the concept of "truth" is reducible. Any argument about the question "what does truth mean?" implicitly requires that participants can already make some sense of the idea that some answers would be true and others would be false. Also, it seems like you're implying that unverifiable claims are meaningless - but isn't that an unverifiable claim?
Putting that aside, some things are unverifiable yet have concrete ramifications for people's lives. Some examples:
- If "earth will be swallowed by a black hole in ten seconds" is true, I'll never be able to verify it, even though it will have the concrete effect of ending my life.
- I can't verify _or_ falsify that other humans have conscious experiences, but I believe they do. If that belief happens to be false, the world is vastly different than if it is true.
- _Nobody_ could 100% verify that a given physical law applies everywhere at all times. But if it does, some people's lives will be different than if it did not. The fact that everyone in the cosmos has experiences consistent with the law being true, and nobody ever has an experience inconsistent with the law, are part of what make the law true. But that fact can't be verified by anyone.
(A hypothetical omniscient person could verify all these things, but omniscience just means "knowing all true things", so redefining truth in terms of what an omniscient person could verify would be circular.)
Putting that aside, some things are unverifiable yet have concrete ramifications for people's lives. Some examples:
- If "earth will be swallowed by a black hole in ten seconds" is true, I'll never be able to verify it, even though it will have the concrete effect of ending my life.
- I can't verify _or_ falsify that other humans have conscious experiences, but I believe they do. If that belief happens to be false, the world is vastly different than if it is true.
- _Nobody_ could 100% verify that a given physical law applies everywhere at all times. But if it does, some people's lives will be different than if it did not. The fact that everyone in the cosmos has experiences consistent with the law being true, and nobody ever has an experience inconsistent with the law, are part of what make the law true. But that fact can't be verified by anyone.
(A hypothetical omniscient person could verify all these things, but omniscience just means "knowing all true things", so redefining truth in terms of what an omniscient person could verify would be circular.)