A Scholastic essay concerning the errors of René Descartes

Does the world around you exist, or do you, as a thinking being even exist, and can you know for certain? These were questions that the philosopher Rene Descartes grappled with in the 17th century. But in doing so, he eventually split off from the Thomistic or Scholastic perspective of epistemology and created his own field which is that of Rationalism. From this also came more philosophical errors such as the Empiricists and further, even the idealism of Kant. Today we’ll explore where Descartes went wrong and how the philosophy of St. Thomas Aquinas and his followers clearly refutes Descartes methodology and gives a much clearer answer to the question of the existence of the world outside your mind and even your own existence.

Descartes employed a methodological approach known as “Universal doubt” or “Cartesian Skepticism” to establish a firm foundation of certainty. This process involves systematically doubting all beliefs, including one's senses, rational faculties, and even one's own existence, until reaching an undoubtable proposition or belief. Descartes aimed to identify a “first certainty” - a foundational truth that could withstand even the most rigorous skepticism. Through this process of hyperbolic doubt in which he universally doubted everything, he arrived at the conclusion that the very act of thinking was irrefutable. Even if all else could be doubted, the fact he was engaged in this process of doubting proved his existence as a thinking entity, as he must necessarily exist if he is doubting his existence. This realization is encapsulated in Descartes’ famous Latin phrase ‘Cogito Ergo sum’ - I think, therefore I am”. 

Rev. Charles Coppens, a Jesuit Scholastic writer from the 20th century, wrote a critique on Descartes in his book “a Brief Text-book of Logic and Mental philosophy” On page 65 he writes: “That is absurd which affirms and denies the same thing; but the doubt in question does so. For in it the philosopher (Descartes) begins by denying the reliability of reason, and at once implicitly affirms its reliability by using it to prove his own existence: "I think, therefore I am." He pretends to doubt all his faculties, and still, he treats the guidance of those same faculties as reliable.”

What Rev. Coppens is asserting is that Descartes puts his very own rational faculties into doubt, but then uses them to prove his own existence. Therefore, Descartes is violating the principle of noncontradiction in that he is affirming and denying his own rational faculties at the same time and therefore his universal doubt is illogical and thus impossible. And further Cardinal Tommaso Zigliara O.P. puts it similarly, “Nay, once the principle of contradiction has been placed in doubt, even if only hypothetically, the “cogito, ergo sum” itself can be asserted as a certain principle only illogically for, by the very hypothesis in place, I must be in doubt whether I can simultaneously think and not think as well as simultaneously whether I exist and do not exist. Therefore, wherever Descartes may turn himself, he will find himself in open self-contradiction.” (Summa Philosophica vol. 1, 8th ed. Pg. 200)

On the topic of the principle of noncontradiction, which is just that a thing cannot, exist and not exist at the same time, or be and not be at the same time and in the same manner. The 18th century Thomist Salvator M Roselli O.P in his work on Summa Philosophica. Roselli writes: “Now, the Cartesian utterance, “I think therefore I am” presupposes other principles, namely: whatever thinks, is; whatever acts, exists; action follows on being; it is impossible that one and the same thing simultaneously be and not be.” (Summa Philosophica, vol.5, pg.9).

And so using the principle of noncontradiction, Roselli shows how it is impossible for Descartes to have his first and certain idea be that of his thinking, when the principle of non contradiction comes before the Cogito or the I think therefore I am proposition. Therefore Descartes’ rationalism, which relies on the fact that his first principle is that he is thinking, is refuted, since many principles such as non contradiction are presupposed beforehand. Now that we’ve demonstrated that Descartes is presupposing many principles before his famous, I think therefore I am, statement, can Descartes even presuppose these principles without the external world outside of him since he puts the external world and his senses into doubt and doesn’t think that their certain. St. Thomas Aquinas says in ST I-II, q. 94, a. 2: “That which first falls into apprehension is being, the understanding of which is included in all things that someone can grasp. Therefore, the first indemonstrable principle is that we cannot affirm and deny (Or: being is not non-being), which is founded on the formal character of being and non-being. ‘And this principle is the foundation for all the other principles’, as the Philosopher says in Metaphysics Bk. 4, Ch.3’”

From what St. Thomas says, the first notion of the intellect is being which is that a thing exists, but if this is true, it destroys descartes’ fundamental basis of knowledge, which is the cogito, because the cogito presupposes another principle in order for it to be true, which is the principle of non contradiction, or in other words to fully understand the implications of the cogito, you must first comprehend the concept of being. On this basis, Descartes’ foundationalist argument is revealed to be flawed; to establish a true foundation, Descartes must first apprehend being which is only possible through his senses which implies an external world around him for where he gets these sensations from. To demonstrate this, we must understand the peripatetic axiom, which states “nothing is in the intellect that was not first in the senses”, which means all human knowledge begins with sensory experience, and therefore sensible experience such as sight, and touch are required for intellectual cognition or to have knowledge at all. In the fact that we have sensory experience and that this sensory experience exists or has being, it is self-evidently the case that we exist, since we couldn’t perceive sensory experience if we didn’t exist. 

Now that we know we exist, can we be certain that the external world exists and that the various sensations which we perceive with our sight and touch come from real objects around us. Yet again Rev Coppens refutes this error that we can somehow doubt the external world, in regards to the various sensations which we perceive, he writes: “Nothing exists without a reason for it; but there exist in us, as we know by consciousness, (a) Sensations; (b) Irresistible judgments that those sensations are caused by bodies, i.e., by substances distinct from our mind, extended and resisting; therefore a reason must exist for those sensations and for those irresistible judgments. But that reason can be none other than bodies really existing; therefore they really exist. We prove the last minor: If that reason were not in the bodies, it would be either, 1. In our minds, as Fichte maintains; or, 2. In God, as Berkeley supposes. No other reason is assigned by our opponents. Now, it is, 1, Not in our minds. If it were, we should produce those sensations and judgments necessarily or freely; but we do neither: (a) Not freely, for we see, hear, feel, etc., many things which we are totally unwilling to see, hear, feel, etc.; (b) Not necessarily; for if we were so constituted that we necessarily elicited false judgments, our intellect would be essentially unreliable; it would be a power, not of knowing truth but of deception and falsification. 2. Not in God. Those who admit the existence of God at all, as Berkeley and his followers do, admit that He is the infinitely perfect Being; but a perfect being is essentially truthful and cannot be the source of a universal deception, as He would be if He produced those phantasms and gave us at the same time an irresistible impulse to judge falsely of their cause.” (Brief Text-book of Logic and Mental Philosophy, pg 83)

Another objection might state that our brain could just be in a vat and an evil genius or scientist just stimulates it and causes fake imagery and sensations. Rev. Coppens refutes this as well, he writes: 

“‘Question: An evil genius could produce the deception.’ 

Answer: We deny this; for the deception, if it were, would be, not accidental, but natural and essential to man, and therefore it would be essential to man to judge falsely; and thus universal Skepticism would become reasonable.” Coppens posits that if an evil genius existed, all our beliefs could potentially be the result of deception, leaving us without means to verify the veracity of our perceptions. He argues that such pervasive deception would not be accidental but rather an intrinsic aspect of human nature. If false judgment were inherent to human cognition, it would imply that our cognitive faculties are fundamentally flawed, predisposing us to erroneous judgments. Consequently, if erroneous judgment were an essential characteristic of human nature, universal skepticism—the act of doubting all beliefs—would appear to be a rational stance. However, universal skepticism is inherently self-refuting, constituting a reductio ad absurdum. By doubting everything, one must also doubt the validity of universal skepticism itself, creating a logical contradiction and rendering the position untenable. Hence, using the Scholastic method and the thought of St Thomas Aquinas and his followers, it is evident that we not only exist through our apprehension of being through our senses such as sight and touch, but that the world around us also exists, as to reject this would lead to absurdity. Descartes departed from this consistent and pure tradition of scholasticism and brought himself and his rationalist sect to the land of absurdity.