Thomas treatment of truth in questio 16 is interesting, I think, primarily for the discussion of the relationship between the true and the good (Q16A3). Obviously the correspondence theory of truth has its well known problems.
The good is ”that which all desires”, whereas truth is the equation of thought and thing (A1). What joins them is that both are convertible with being, i.e. we desire that which is, and we know that which is. They are in a sense complementary, since the good is said to recide in the thing that is desired, whereas the true is primarily in the intellect. This means that the same way evil is privation of good, falsity depends on truth:
Falsity is not founded in the truth which is contrary to it, just as evil is not founded in the good which is contrary to it, but in that which is its proper subject. This happens in either, because true and good are universals, and convertible with being. Hence, every privation is founded in a subject that is a being, so every evil is founded in some good, and every falsity in some truth.
