Are there philosophical or cognitive theories about "creating truth by defining"?

Question

Are there philosophical or cognitive theories about "creating truth by defining"?

Particularly, I refer to a phenomenon of saying something and then having it become true, because of how it's said.

It's a bit like "pure a prioric reasoning", but since there are also valid a prioric reasonings that also have broader than a priorical truths (e.g. mathematics), then this is not exactly it. Rather, "creating truth by definition" would be to formulate premises from scratch and then have them become truths by some other means than "tying them to natural sciences" for example.

Particularly, this phenomenon makes it possible to create "plausible theories" and "plausible premises" out of nothing and then have them appear valid, because of their plausibility, believability etc. If these touch contexts that are uncertain or out of which absolute truth cannot be found, then these might also be interpreted as "as true as there can be".

Answer 1

The idea of “creating truth by defining” might be viewed as what Plotinus calls “creative contemplation”. For an overview of Plotinus see the Stanford Encyclopedia of Philosophy’s entry on Plotinus https://plato.stanford.edu/entries/plotinus/ and for a translation of the Enneads see http://www.sacred-texts.com/cla/plotenn/index.htm.

Although this jumps right into the deep end of neo-Platonism which may not be easy to understand, one can get there through modern physics. See Shimon Malin’s Nature Loves to Hide for an introduction to Plotinus from the perspective of asking questions about the collapse of the wave function. He describes creative experiences of Einstein, Bohr and Heisenberg in terms similar to what you are using.

Another place to look is the concept of “motivated reasoning”. https://en.wikipedia.org/wiki/Motivated_reasoning Although motivated reasoning is associated with self-deception and bias, it might be a way to describe our normal thinking process: we get an insight instantaneously and then rationalize it. That moment of insight would correspond to your "pure a prioric reasoning". When that insight is wrong or socially unacceptable it is call self-deception or rationalization. When it is right, perhaps we give too much credit to our rational process for arriving at the answer. Crediting "reason" for a gut insight we accept emotionally may be another form of rationalization. See Antonio Damasio’s research on brain disorders blocking empathy in Descartes’ Error and Jonathan Haidt’s description of the rationalist delusion, based on Damasio’s work, in The Righteous Mind for more information.

EDIT: I asked a related question recently: Do theories come from observations or do they determine what is observed?. See Conifold’s answer and references, in particular the reference to Nersessian, for another approach to this.