It is not accidental that the final section of Hans-Georg Gadamer’s Truth and Method explicitly identifies the intimate relationship between the so-called “transcendentals”, being and truth, as a tragic loss in the modern age. As transcendentals, being and truth are the conditions of possibility for ancient and medieval metaphysics and epistemology, respectively. In a well-known passage from the Summa Theologiae, Thomas Aquinas has this to say on the subject:
As good has the nature of what is desirable, so truth is related to knowledge. Now everything, in as far as it has being, so far is it knowable. Wherefore it is said in De Anima iii that “the soul is in some manner all things,” through the senses and the intellect. And therefore, as good is convertible with being, so is the true. But as good adds to being the notion of desirable, so the true adds relation to the intellect.
As the good is “convertible” with being, so is truth convertible with being. But why is this the case, for Thomas? The point is a rather simple one: namely, that things can only be known insofar as they are in some sense. Even the purely logical idea of the negation or nothing, he argues, is constituted in part by faculties of reasoning that are themselves. As such, there can be no truth without being.
Gadamer likewise realizes the intimate relationship between being and truth in the ancients: “They did not try to base the objectivity of knowledge on subjectivity. Rather, their thinking always regarded itself as an element of being.” Against the modern idea of justification as a “first philosophy”, of sorts, Thomas and Gadamer are both hermeneuticians in the sense that they want to provide concrete descriptions of the phenomenon of truth as a concrete, active manner of being-in-the-world.
In Being and Time, Heidegger criticizes Thomas’ concept of adaequatio between mind and world as a sort of proto-correspondence theory characteristic of modern and contemporary representationalism. Leaving aside the question as to whether this is good intellectual history or not, it is clear from not only Thomas’ work in Question 16 but from Gadamer that this sort of anthropology is just not operative in the Summa. Spatial metaphors (i.e. truth resides “in” the intellect) are not to be taken literally here; for we cannot forget that Thomas’ concept of the intellect is not at all a “ghost in the machine” but rather the active principle of the process of knowledge. Again, just like the hermeneuticians such as Heidegger and Gadamer, Thomas wants to avoid saying that truth is a static correspondence between mental concepts residing in a mysterious spatial realm called the intellect. Such a conception would make convertibility between transcendentals an impossibility. Thus, as James Orr remarks in a forthcoming article in New Blackfriars, it may be the case that “recent treatments of Heidegger’s [and Gadamer, by extension] readings of Aquinas have tended too hastily to deny the possibility of any fruitful dialogue between them.”