This blog post examines the limits of the cognition-fact comparison faced by the classical concept of truth, clearly outlining how the structure of infinite regress Kant described connects to our conditions of cognition.
According to the classical formulation popularized by Thomas Aquinas, ‘truth’ is understood as ‘the agreement of things with the intellect,’ a concept whose origins can already be traced back to Plato. However, significant similarities and differences exist between Plato’s terms for truth, ‘orthodes’ and ‘aletheia,’ and Thomas Aquinas’s ‘veritas’. In the Cratylus, Plato held that not only propositions but even individual words could be true or false. Yet in the Sophist, he maintains that speech possesses truth value only when it functions as a proposition—that is, when it asserts factuality through the connection of subject and predicate.
For example, in a true proposition like “Deidetes sits,” the connection between ‘Deidetes’ and ‘sits’ is affirmed as existing. Conversely, in a false proposition like “Deidetes flies,” a non-existent connection is affirmed as existing, or an existing connection is denied as existing. Plato’s orthodes refers to truth established in this manner when a proposition is true.
In the Republic, Plato presents aletheia, or ‘unconcealment,’ as another aspect of truth. Without the sun, visible objects remain unseen, but thanks to the sun, objects are revealed. Similarly, without the Idea of the Good, the Ideas of the intelligible world remain hidden, and our reason cannot know them. It is through the Idea of the Good that the Ideas become knowable. Just as sunlight connects the visibility of objects with our sight, the Idea of the Good mediates the knowability of the Ideas with our capacity for knowledge. That is, the Idea of the Good enables the aletheia of the Ideas and our orthodesis of them.
Later, Thomas Aquinas’s concept of veritas as the ‘conformity of things to the intellect’ is divided into ‘conformity of things to the intellect’ and ‘conformity of the intellect to things’—that is, into factual truth and propositional truth, possessing mutually symmetrical directions. His theory of truth inherits Plato’s perspective in that ontological truth and epistemological truth are discussed together. However, a significant divergence exists in his view that truth is ‘originally’ constituted in human cognition through propositions. This stems from the understanding that, since things are the practical manifestation of divine intellect, nothing is fundamentally untrue in this world; the arena where questions of truth and falsehood arise primarily lies within the domain of human intellect. Ultimately, it rests on a worldview where truth is only fully realized through genuine human cognition.
Subsequently, in the history of philosophy, propositional truth tended to become the central focus of discourse among the two dimensions of Veritas. Regarding this, it is possible to criticize that limiting truth to the propositional level constrains philosophy’s inherent guiding function, since philosophy’s task lies not only in ‘true’ cognition of the world but also in leading the world closer to ‘truth’.
However, even if the scope of truth discourse is limited to the propositional level, a significant structural difficulty exists in the classical formulation. According to Kant, to judge the truth or falsity of any proposition—that is, of any act of cognition—one must compare that proposition with an objective fact to verify whether they coincide. However, this process inevitably leads to infinite regress. To perform the comparison, one must first know that ‘fact’; thus, we end up comparing cognition with cognition, and that second cognition must then be compared with yet another fact. Yet that ‘other fact’ must necessarily be yet another piece of knowledge. Thus, we can never reach objective facts as the standard of truth.
Kant locates the root of this infinite regress in the structure of human cognition—specifically, in the circularity of knowledge that cannot escape subjectivity. What we call ‘things’ are ultimately only the things ‘we’ have experienced—phenomena—and never the ‘things-in-themselves’ as they exist. Therefore, he argues, the natural laws revealed by science are not the laws of nature itself, but merely the internal structure of our mind operating as a condition of experience.
