I'm actually trying to get at something far simpler. For instance, the question "who was the President of the United States in the year 2,000?" has, by any definition, only one true answer which is knowable by anyone who can understand the question.
Even this simple question is going to yield a different result if we change the conceptual frame. Bill Clinton gets our commonsense answer, but certain conceptual schemes might reject that answer. Remember the Heraclitus remark "you cannot step into the same river twice"? A conceptual scheme that is a based on an non-macro object ontology (e.g., quantum ontology, event ontology, process ontology, etc), might see the answer 'Bill Clinton' as misleading and false.
It is ironic to have all those debates on truth when we deal with it on a daily basis.
It is ironic, but I think most of us accept a commonsense realist notion of truth that works well enough in most situations, but fails when as a definition when adequately analyzed.
Harv: The scientific methodologies aren't a pure formal system, but they are much more formal than casual discussion, and we use the methodologies of these formal enterprises to determine what is 'true'. Mike: No, science has nothing to do with truth in principle. You can have true science and false science. In fact, science's power would be severely diminished if we weren't able to produce more false science than true science.
That's why I put quote marks on the term 'true'. I agree, science is based on models that provide adequacy in terms of prediction, retrodiction, and explanation (among others). My point is that most of us treat as 'true' the results of good theories. If asked about where humans first appeared, I think most of us would unhesitantly say the continent of Africa. This is a scientific discovery, and it is to be regarded as 'true'.
What you are saying can be interpreted as this: a true statement in one language may be false when translated to another language. But if you take my definition of truth, your proposition becomes a non-sequitur, as only true ideas can be communicated. If a statement may be false upon translation, that means it is not true even in the original, it only appeared to be true. It was an illusion.
Accurate translations may not even be possible. For example, in the case of the above, I cannot see how it is possible to translate an macro object ontology that allows for the existence of a Bill Clinton to in anyway accurately describe a 'Bill Clinton' that is composed of trillions of quantum events that take place over decades. Such kind of reductionism from a macro Bill Clinton object to a 'Bill Clinton' composed of trillions of quantum events might be possible, but there are some good arguments to suggest that such reductions are not possible. The ontologies might fundamentally conflict and that in terms of translations we might be talking about incommensurables in the sense of a Kuhnian paradigm shift. So, let me change T2:
T2': "P contextually obtains and not P contextually obtains for every possible proposition depending on the conceptual scheme Cx used to determine P and not P. Conceptual schemes Cx(1-n) may be incommensurable between each other"
The trick is to come up with a definition of truth that makes T2 impossible. Admitting the possibility of T2, even if just in principle, is equivalent to saying truth does not exist. As I said before, "truth does not exist" is not a valid proposition in any language, formal system, conceptual scheme. Notice there's a difference between truth not existing and our not being able to say such a thing. For instance, I can conceive of a world in which I cannot make any assertions, but I cannot, at any time, assert that I'm not able to make assertions.
Well, let me clarify by what "truth does not exist" is supposed to mean. It means that no particular conceptual scheme captures the essence of ding an sich and, as you pointed out, I should mention that conceptual schemes can be incommensurable (T2') with each other. Now, if you can define 'truth' that satisfies this criteria (T2'), then you may be onto something, but it won't be how most people think of truth. It could just as well be false, and perhaps would be false to some other conceptual scheme that has perhaps equal claim to being 'true'. Again, I'm not saying T2' is the case, just that it must be considered as a possibility.