A Scholastic essay concerning the errors of David Hume

Over the centuries since St. Thomas Aquinas in the 13th century, many philosophers have moved away from the realm of metaphysics and metaphysical argumentation. Instead, they have rejected such metaphysical principles and substituted it for materialistic or nominalistic means. No longer is there a universal conception of what it is to be a human being or even an animal, everything is just a particular instance of matter in motion. This conception of reality, as will be argued today, completely breaks down into a self-refuting position or a reductio ad absurdum. Yet we find that one of the culprits for this mess was none other than the philosopher David Hume. In this essay we’ll show how his position of empiricism, which many atheists in the modern day take, is illogical and cannot be held without the destruction of knowledge itself. We’ll also show how the thought of St. Thomas and the Scholastic tradition refutes David Hume and offers a consistent and reliable world view. Now before we see how the thought of St. Thomas refutes Hume’s empiricism; we must understand what Hume taught. 

Hume’s Empiricism is opposed to rationalism which posits the idea of innate knowledge, which means certain truths or ideas pre-exist in the intellect prior to any experience. And in consequence Hume argues that all human knowledge originates from sensory impression. Hume states “By the term impression, then, I mean all out more lively perceptions, when we hear, or taste, or feel, or love, or hate, or desire, or will” (A Treatise of Human Nature, Book l, Part l, Section l). Hume here defines impressions as the lively and forceful perceptions that the mind experience directly through the senses. Now according to Hume, there are two types of impressions, impressions of reflection, and impressions of sensation. The former is of internal experiences, such as desires, or feelings, and this arises after the mind reflects upon its own operations, the latter is from external sensory input, such as coldness, smell, taste, ect... And after Hume's thesis, he concedes to a position of skepticism using his famous problem of induction, in which it involves generalizing past ideas, which are vague representations of impressions from prior experiences to infer mere probable conclusions rather than certain conclusions. Therefore, there is no logical guarantee that the future will resemble the past. An example of this is: “if we observe that every swan we have seen is white”, then we can infer that all swans are white. This is called the principle of uniformity of nature. To infer that all swans are white, we assume that the pattern observed in the past will continue in the future. But Hume argues that this doesn't justify universal claims, because the principle of induction itself assumes uniformity in nature, which cannot be empirically demonstrated.

When it comes to causality Hume states “All inferences from experience, therefore, are effects of custom, not of reasoning” (Enquiry concerning human understanding, section V, Part l), and also further states: “When we look about us towards external objects, and consider the operation of causes, we are never able in a single instance, to discover any power or necessary connection” (Enquiry Concerning Human Understanding, Section Vll, Part l). Hume here states that we never directly observe a necessary connection between cause and effect, but it is a habit of the mind from constant conjunctions, meaning that when we have the impressions of cause and effect, we form an expectation that an effect will precede the cause. And the mind projects this connection on the external world because of repeated experiences, this necessity exists only as a subjective feeling of expectation not as an objective principle in the external world. Negating its universality as a first principle. On Hume’s position of nominalism, he states that “The mind is never to be considered as having any distinct idea of a general or abstract object, but as being led by custom to apply one name to a great number of distinct objects which are all of the same kind. The idea of a triangle, for instance, is not the idea of any particular triangle, but of a kind of figure that may be represented by any number of triangles.” (A treatise of Human Nature, Book l, Part l, Section Vll). Here Humes rejects the ontological and epistemological reality of universals, and states that a collection of distinct objects which are similar are labeled with the same name, but that they do not share a universal, which are immanent realities in the particulars, an example would be the idea of redness, there are many red things, but what makes them red is the fact that they are instantiated with the universal of redness. 

Now going in order of the beliefs of Hume that we just touched upon, we will first cover Hume’s ability to perceive sense data or impressions which is the basis for his ability to have knowledge at all. Now in Hume’s inquiry concerning human understanding, he writes about the external world. “These are the obvious dictates of reason; and no man, who reflects, ever doubted, that the existences, which we consider, when we say, this house and that tree, are nothing but perceptions in the mind, and fleeting copies or representations of other existences, which remain uniform and independent…By what argument can it be proved, that the perceptions of the mind must be caused by external objects, entirely different from them, though resembling them (if that be possible) and could not arise either from the energy of the mind itself, or from the suggestion of some invisible and unknown spirit, or from some other cause still more unknown to us?”(A treatise of Human Nature, Book l, Part l, Section I)

Quite simply, Hume literally admitted to the fact that his empiricist mode of knowledge allows for false sensory experience or impressions. Meaning, that he couldn’t truly know whether or not the external world is how he perceives it. Hume grants the possibility of his very senses being altered by his own mind or an invisible spirit. But if Humes whole system of knowledge is based on sensory experience, then he cannot hold anything he thinks for certain and therefore falls into universal skepticism or the idea that one doubts everything. Of course, this is an impossible or reductio ad absurdum position to hold as you can’t doubt that you doubt everything."That theory is self-contradictory, which affirms and denies the same thing; but such is the theory of universal Skepticism.” (Brief Textbook of Logic and Mental Philosophy, pg 58-59) Now another issue which Hume espouses is that of his view of casualty. Yet again, Hume does not think that same effects must necessarily precede causes. Hume argues that we simply just have the habit of expecting a certain effect from a certain cause as the night follows the day. Now the issue with Hume’s view on casualty is that it leads to completely absurd propositions. Fr. Garrigou-Lagrange writes, “This would represent a kind of suppression of common sense (that is, of the intellect's natural power of understanding). The murderer could say to his judges, ‘I was not really the cause of this murder. It is a fact which followed upon my own actions, just as the day follows the night without being caused by it.’”(Philosophizing in Faith). 

Essentially, basic reasoning which uses causality falls into absurdity and disarray. To simply move from premise 1 to premise 2 in a logical argument requires the principle of causality. In order to avoid this self-refuting and reductio position, we must turn to the scholastic conception of causality that we find in St Thomas. “For, given the cause, its effect must follow.” Now the connection between cause and effect is not something which is part of sense experience in so far as I observe cause and effect, the principle of causality is an a priori principle abstracted from intelligible being. Sense experience of cause and effect merely confirms the principle of casualty. Now what is meant by the concept that the principle of causality follows from intelligible being. Well for the scholastics we would say that all knowledge begins in the senses, this is the peripatetic axiom. Further, in so far as the senses perceive sight, touch, hearing ect.. Which all have being or existence, we are able to abstract principles from being, such as the principle of non-contradiction. 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’’

Now one of these principles that follow forth is the principle of sufficient reason. This principle states that there is nothing without a sufficient reason for it or its existence. And to deny this principle would be to fall into reductio ad absurdum . Logical argumentation itself involves the principle of sufficient reason, as one has a sufficient reason to go from a premise to the conclusion.Rev. Coppens states: “The principle of the sufficient reason is an analytical judgment so obviously evident that we cannot rationally deny or even doubt it without thereby implicitly affirming it; for rationally to deny or doubt it we should see some reason for so doing; and thus we admit the validity of the principle, denying it because we see a reason for so doing.” (Brief Textbook of Logic and Mental Philosophy, pg 48). This very principle is also the basis for the principle of causality, for when anything begins to exist, there must be a sufficient reason for this beginning. So, Hume’s whole critique of the necessary connection between cause and effect is blatantly refuted by the scholastics and the thought of St Thomas, as this principle is a fundamental basis of reasoning. In fact, Hume’s conception of causality loses any intelligibility when you consider for example that if the same cause, in the same circumstances, did not produce the same effect, that change in the effect, without a previous change in the cause or the circumstance, would be without a sufficient reason for its existence. This simply makes all science impossible, as Humes essentially has thrown out all regularity. 

Now such a refutation would be considered sufficient, but nonetheless we will continue to the next issue of Hume’s nominalism. Now it's important to note that many secular and modernists in philosophy today utilize nominalism and reject moderate realism, so it's of importance that we refute this error. Now we have demonstrated the importance of first principles and how they relate to intelligible being or existence through sense data. But there arises an issue concerning Hume’s conception of reality, in so far as he does not think we can have a universal conception of being or existence, in fact he wouldn’t even affirm that things have existence as a moderate realist would. He would simply say that they just are in reality. Not only that but, as we argued earlier, cannot even trust his senses to offer proper sense data concerning the world and therefore he has no basis or grounding for first principles. But if that is true, then Hume has just thrown out all of the first principles which come from being. For example the foundation of all first principles, is that of the principle of noncontradiction, or the idea that being is not non-being, or existence is not non- existence. To reject such a principle would destroy all cognitive reasoning as one could say that a square could be a circle at the same time. Or that this principle of noncontradiction is both true and false, this is just meaningless and an impossible position to hold to. But this is what the nominalism of Hume leads too.

The scholastic tradition and especially the thought of St. Thomas clearly offers a consistent worldview that does not reduce to absurdity. We have clearly shown that Hume’s position leads to an extreme form of phenomenalism or the idea that you can have no consistent knowledge of the exterior world. For Hume, his senses could be misleading him, but Humes whole position is based on his senses and particular sense impressions. And therefore Hume refutes himself, as he now has made knowledge impossible. Further his view on casualty simply reduces to absurdity once we consider the principle of sufficient reason and causality. Finally, Hume’s nominalism which many materialists in today's world also seem to take, becomes an impossible position, as even this view leads to the impossibility of reasoning, as he has no ability to utilize the first principles such as noncontradiction which stem from being or existence itself as he doesn't hold to moderate realism. Fr. Garrigou-Lagrange argues that Humes world view is so absurd and impossible that it actually gives credence to Scholasticism and moderate realism. He writes: “Hume's system provides a proof of traditional realism by way of a reductio ad absurdum and that even if it did not exist, one could invent it in order to demonstrate the true sense and scope of traditional realism. In fact, Divine Providence only permits these errors in order to shed light on the truth.”(Philosophizing in Faith).