In abstract terms, "truth" is an aspect of set theory and standard mathematical necessity. For example if A contains B and B contains C, the A contains C. We tend to model reasoning about the world on such abstractions as in the syllogism. But the assignment of "truth values" for set membership (i.e the choice of axioms) is a social or paradigmatic convention, (Barack Obama could have red hair as far as syllogistic logic is concerned). Nor, can we ascribe universality
to many statements about "reality" because unknown contextual variables can delimit the application of axioms We therefore pay lip service to the models, and settle for probabilistic reasoning and induction, rather than truth/certainty. This has led to the pragmatists concept of "truth" as "what works subject to revision".
So "reason" is the tentative application off fruitful
mathematical models, but with "consistency" replacing "truth" as an epistemological criterion. I am fond of the example of Clerk-Maxwell's equations for electromagnetism which were axiomatically based on the assumption of an elastic medium called "the luminiferous ether". Later rejection of the existence of the ether did nothing to mar the "success" of the equations in predicting electromagnetic observations. Indeed, as far as "consistency" is concerned in physics,the properties of symmetry and elegance have proved to be more epistemologically fruitful than "truthful axioms".