There are two forms of truth that we have to deal with:
- Truth of existence. Does an object or phenomenon exist in reality?
- Truth of statements. Is a statement true or false?
In real life both are equally relevant. We are surrounded by and part of the physical world. The world of language and statements is but a subset of our world, but a very important subset and the subset that is the primary focus of what separates humanity from the rest of the physical world.
But inside of a computer, where reality is kept at a distance and almost literally is a separate and distinct universe, truth is concerned mainly with statements and the notion of existence outside the realm of inside of a computer is itself a mere statement. In other words, the computer can know about the real world only to the extent that we seed its pool of statements with statements about the real world that we know to be true. We must define what is true of the real world.
If truth of existence means anything inside of a computer, it is simply as statements making assertions about the real, outside world, statements which a computer cannot evaluate per se and whose truth can only be obtained by human or other physical input in statements whose only justification is of the form "because we, agents of the outside world, say it is so."
In short, beliefs about the outside world are true inside of a computer only to the extent that we external agents have correctly encoded our external truth into machine-cognizable statements of truth. We must define truth about the outside world. Unfortunately, we may be wrong or may make mistakes when doing such encodings, so there is the risk that a computer may not start out with a true understanding of the outside world.
Eventually, ultimately, as we embellish computers with sensors and the ability to directly "learn" from those sensors and human documents and other artifacts, it may be possible for a computer to directly "learn" at least some aspects of truth in the real world. But, once again, truth inside the computer will be limited by pre-programmed assumptions about how sensors and human artifacts work. After all, how can a computer "know" whether our manufactured sensors accurately convey "the truth of the real world" and don't distort this "truth" in some ways of either malevolent or accidental nature, sometimes even despite the best of intentions or maybe because of the worst of intentions.
Could we construct the ideal criminal or achieve some ideal sense of evil, either by accident, negligence, or by intention? We may even create evil simply as a test case, but will we be able to control it? Or maybe someone may create evil because they do seek to control it, or maybe someone might create an intentionally uncontrollable evil solely in the pursuit of chaos.
In any case, achieving alignment between the truth of the world and the truth of statements within a computer is a tricky business to be sure.