The phrase "a theoretical truth" is correct and usable in written English.
It can be used when discussing concepts or ideas that are considered true within a specific theoretical framework or context, rather than empirical evidence.
Example: "In philosophy, the concept of free will is often debated as a theoretical truth that influences our understanding of moral responsibility."
Alternatives: "a conceptual truth" or "an abstract truth".
These studies of ancient sexuality, and, particularly, the idea of an aesthetics of the self, led Foucault to the ancient idea of philosophy as a way of life rather than a search for theoretical truth.
Discussions about the theoretical truth of pictures are important, but of little immediate value in the trenches of practical policy-making.
Second, although religion, according to Spinoza, is not concerned with theoretical truth, in order to be effective the religio catholica requires dogmas, which he set forth in the Tractatus.
How then are we to decide whether to believe in the full theoretical truth of scientific theories, including what they say about unobservable entities such as electrons and black holes, or whether to believe instead merely that our best scientific theories are empirically adequate?
In this strict sense only fully interpreted sentences are logical truths (or just truths), and theoretical truths that are asserted peculiarly by logic as a science need not be logical truths.
In what is perhaps the most relaxed technical usage, the theoretical truths that are asserted peculiarly by logic as a science, e.g. "(1) is a logical truth", are called "logical truths".
1. Implement approaches that focus less on theoretical truths and more so on promoting pluralism.
That doesn't mean it will (or that it can), but the current debates within the discipline (as opposed to what occurs in the public square) really threaten some fundamental theoretical truths -- not unlike what occurred in the '30s with Keynes.
Finally, at the other end of the practice-theory spectrum, there is bioethics as a theoretical pursuit of truth, a variant unhindered by the resolutely practical constraints of the clinic and commission.
Besides an intended gain for his system of "Basic Laws" (Frege 1962) reflected in enhanced technical clarity, simplicity, and unity, Frege also sought to substantiate in this way his view on logic as a theoretical discipline with truth as its main goal and primary subject-matter.
