The Lingering Objection: Deficiency in Descartes’ Replies to GassendiSeptember 25th, 2023Descartes’ well-known proof of the existence of God in the Third Meditations relies on his ability to possess an idea with infinite objective reality. This is a critical premise in his proof; without it, the proof fails. I argue that Descartes did not possess an idea with infinite objective reality. This objection was raised in Descartes’ lifetime, notably by Gassendi in the Fifth Objections. Descartes’ replies to this and a thread of related objections offered unsatisfactory, unconvincing replies. I am considering the following line of objections by Gassendi: G1. humans cannot conceive of the infinite; (M171-3/AT284-97).[1] While I am ultimately concerned with arguing for G1, I will get there by way of addressing the other two. I share Gassendi’s contention in G2 that the ideas to which Descartes ascribes infinite objective reality are instead augmented—or amplified—ideas with finite objective reality. G3 offers more direct and specific reasoning as to why Descartes is not correct in positing that he can conceive the infinite. I will proceed as follows. In section one, I will detail the premises of Descartes’ proof of God’s existence that are most relevant to my argument, giving particular attention to the premise I intend to refute—premise five, as enumerated in section one. I will also summarize his causal adequacy principle and its bearing on Descartes’ reasoning. In section two, I will relate and briefly evaluate the distinction Descartes makes between infinite and indefinite. In section three, I will explore G2, the objection that Descartes’ ideas are of augmented, finite human perfections. In section four, I will address G3, the objection that knowing some part of the infinite is not sufficient for knowing the infinite. Finally, I will conclude that without a robust defense of the claim that he possesses an idea with infinite objective reality, Descartes’ proof of God’s existence fails. I. The Proof and the PrincipleDescartes’ proof of God’s existence turns on his claim that he has a clear and distinct idea of an infinite being. More specifically, “an infinite, independent, supremely intelligent, supremely powerful substance, by which I and myself and whatever else exits…was created” (M32/AT45). The critical question he then raises is whence came this idea?Descartes’ causal adequacy principle (which I will detail further below) establishes that he—a being with finite formal reality—could not be the cause of this idea of an infinite being because it contains infinite objective reality; instead, the cause of the idea must be something outside of him that possesses infinite formal reality (M29/AT40-1). He concludes that the cause must be God (M32/AT45). The proof itself can be understood by this summary offered in a lecture by Jeffrey Kaplan. The arguments I have assembled refute premise five. If that premise is false, the conclusions in italics (added) no longer necessarily follow. Kaplan summarizes the proof as follows:
[Emphasis added] Now that we have glossed the proof, let us move on to the principle that gives it life. Descartes’ causal adequacy principle is the backbone of his argument. He summarizes its basis in his replies to the second objections: “…a substance has more reality than an accident or mode; and infinite substance more than finite” (M106/AT165). A second distinction of this principle is that of formal versus objective reality. Formal reality is possessed by actual, existent things; this includes existent substances and existent ideas (Smith, 2021; M29-30/AT41). Objective reality, on the other hand, only pertains to ideas, which they possess by virtue of their “being a representation of something” (Smith, 2021; M29-30/AT41). We can combine these notions to understand the causal adequacy principle in the following sense: infinite substances (e.g., God) contain maximal formal reality, finite substances (e.g., animals) contain medial formal reality, and modes (e.g., the color red) contain minimal formal reality. Descartes applies these same three levels to objective reality; e.g., the idea of God contains more objective reality than the idea of an animal, which contains more objective reality than the idea of a color (M29-30/AT41-2). The chief function of this principle, as relates to Descartes’ argument, is how it applies to cause and effect. By Descartes’ lights, “…there must be at least as much reality in the total and efficient cause as in its effect” (M29/AT40). With that final component in place, we can understand how Descartes concluded as he did. If his mind possesses an idea with infinite objective reality, and such an idea requires a cause with as much or more formal reality, then his finite mind could not be the cause of that idea. Instead, the cause must be formally infinite and something other than Descartes. II. Distinguishing Infinite from IndefiniteDescartes insists on a key distinction between infinite and indefinite. This distinction was thoroughly discussed and defended in Descartes’ lifetime, as we have seen in surviving correspondence (Berman, 1993). It would be unwise to move on and question his ability to conceive of the infinite without stopping here for a brief examination. Much of what we might refer to today in common parlance as infinite is what Descartes would label indefinite. Infinite is a notion that Descartes reserves for “something in which no limits of any kind could be found” and which is, therefore, “unlimited in every respect” (Descartes, 2017/1641). Indefinite is a notion that Descartes applies to things that are “unlimited in some respect” but “aren’t unlimited in every respect” (Descartes, 2017/1641). Matter is a helpful subject for understanding his notion of indefinite in two ways. First, we can conceive of matter extending without limit from a given point, as when contemplating the potential vastness and reach of material substance in the universe. As Sophie Berman (1993) wrote of this distinction, “…wherever we arbitrarily suppose the limit to be, we can always conceive that there are parts of matter beyond that limit.” A second way of illustrating this notion in terms of matter is indefinite divisibility. Descartes denied atomism; that is, he denied that there is some singularly small unit of matter which cannot be further divided (M61/AT86). He addresses this most succinctly in the Sixth Meditation: “…no bodily or extended thing can be thought by me that I cannot mentally divide into parts, without any difficulty; and I therefore understand it is divisible” (M61/AT86). This denial of atomism implies that the division of matter could go on ceaselessly, without limit. Descartes is willing to grant of both examples that they appear infinite, but only in some—not every—respect; as such, he would term them indefinite. If Descartes accepted these examples as sufficient for a notion of infinity, he would weaken, if not disprove, his argument for God’s existence. Examples like these concern finite things that are augmented or perceived to extend or continue in number without end. Regardless of their number, finite things contain finite formal reality, and ideas of them—even when augmented—contain finite objective reality, which is not enough to prove God’s existence in Descartes’ proof. Instead, he must show that he possesses an idea, the objective reality of which is infinite by his terms: “something in which no limits of any kind could be found” (Descartes, 2017/1641). This brings us to one of Gassendi’s objections. III. The Objectively Indefinite Objection (G2 and Replies)Gassendi objects to Descartes’ claim that his idea contains infinite objective reality: “[t]he perfections attributed to God are all amplified versions of things we admire in human beings. An idea representing them would have no more objective reality than that of the finite things on which it is based” (M171/AT284-8). If Gassendi is correct here, then by failing to possess infinite objective reality, Descartes’ idea of God also fails to necessitate the existence of a formally infinite being or cause. This objection accurately observes that some of the perfections Descartes mentions finding in his idea of God are also found here on Earth in a finite sense—independence, intelligence, and power, for example (M32/AT45). In the section of the Third Meditations just referenced, Descartes begins with ideas containing finite objective reality and augments or amplifies them with the word “supremely” (M32/AT45). That augmentation does not establish infinite objective reality because the augmented ideas are finite. In short, Gassendi argues that Descartes’ idea of God is composed of what are indefinite attributes in Cartesian terms. Descartes replies to this objection in part by noting the following:
This reply falls short of resolving Gassendi’s objection. Here, Descartes is rhetorically accepting for a moment the notion that we humans could amplify our finite ideas “so as to conceive something greater than ourselves” (M191/AT364-5). He then rejects this notion on the grounds that, to amplify our finite ideas into infinite ideas, we would still need a source other than ourselves for the infinite objective reality achieved at the end of that transmutation. This follows the logic of his causal adequacy principle: even in the rhetorically granted analogy, we remain formally finite and could not cause the resulting objectively infinite idea ourselves. Where Descartes misses the mark entirely is that Gassendi could simply reapply his initial objection. He could deny that “the result is a higher degree of perfection than is found in humans” (M191/AT364-5). He could deny that we have transmuted finite to infinite. At best, he might grant that we have augmented finite to indefinite and again mistaken it for infinite. Ultimately, Descartes’ reply is susceptible to the same objection to which he was responding. Without a robust reply that escapes this objection from Gassendi, Descartes’ argument is susceptible to failure at premise five, as enumerated in the introduction, meaning it is no longer certain that his idea of God contains infinite objective reality. More critically, it is no longer certain from his argument that God exists. IV. Our Limited Conception of the Infinite (G3 and Replies)In generally the same space as the above objection, Gassendi raises a more sweeping dissent. He argues that Descartes cannot possess an idea of the infinite to begin with because such an idea is beyond his capacity as a finite being to comprehend (M173/AT294-7). Descartes seems to have anticipated this objection ahead of time, acknowledging in the third meditation that he does not have a comprehensive understanding of the infinite: “…it is the nature of the infinite that it should be incomprehensible to me, who am finite” (M33/AT46). However, he contends in his reply to Gassendi that his “…idea represents not part of the infinite but the infinite as a whole, so far as a human idea can grasp it” [emphasis added] (M191–2/AT367–8). The second half of that statement seems to contradict the first half. If so, this is troublesome for Descartes’ defense of his ontological proof. He claims to have an idea representing the whole of something but only as much of the whole as his mind can grasp. Gassendi seems to be referring to precisely that limitation in his objection. To that end, Gassendi contends that “knowing a part of the infinite is not to know it, any more than you can know a human being by the tip of a single hair” (M173/AT294-7). Descartes justifies this limitation by arguing that an idea of a three-sided figure is sufficient for the concept of a triangle, despite there being many other properties of a triangle that remain unknown to the perceiver (M192/AT367-8). A notable weak spot in that comparison is that Gassendi could accept it and still maintain his objection. He could even expand on Descartes’ point, perhaps agreeing that we lack full and complete knowledge of the objects of most of our concepts. Still, those concepts—a triangle, a human being, others—do not contain infinite objective reality and, in that sense, are largely irrelevant to this argument. The tip of a hair can at least be measured proportionate to the human body to which it belongs; in contrast, any limited concept of God that Descartes claims to possess is categorically incomparable to the infinite. As such, it fails to offer the same kind of sufficiency achieved in the triangle example. In other words, knowing 10 out of potentially 10,000 facts about something finite may be sufficient for conceiving a finite thing, while knowing 10 out of ∞ facts about something infinite may not be sufficient for conceiving an infinite thing. It is worth noting that the causal adequacy principle I described in section one does not, by itself, require that the cause of a finite substance be an infinite substance. Again, Descartes holds that “…there must be at least as much reality in the total and efficient cause as in its effect” [emphasis added] (M29/AT40). While this principle prohibits, for example, a mode from being the cause of a finite substance, it does not prohibit a finite substance from being the cause of a finite substance. This may seem like a belabored point: were it otherwise—that a cause must always be greater than and never equal to its effect—the causal adequacy principle alone might be proof enough of an infinite being, and Descartes is not making that claim. Nevertheless, I stress this because it highlights why Descartes’ proof relies so critically on identifying a concept with infinite objective reality. Without certainty that he possesses such a concept, the ontological proof cannot succeed. I also raise this because it motivates the heart of my—and what I take to be part of Gassendi’s—objections: you can no more obtain infinite from finite than you can finite from mode. That is the hurdle Descartes must cleanly breach for his proof to hold. It is also the point at which I believe Descartes fails in his replies to both this and the previous objection. I have outlined two objections from Gassendi arguing that Descartes does not possess an idea with infinite objective reality. Descartes replied to both objections, and I have proposed how he failed to adequately escape them in both instances. Without a clear justification for that premise in his ontological proof, we can observe the following:
It is difficult to summon more charitable support for Descartes on these objections, given that he had the opportunity to respond to them in his lifetime and failed to present more compelling evidence of his supposed concept of the infinite. Even in his extensive personal correspondences, where Descartes many times offered further clarification of his distinction between infinite and indefinite, he did not offer further evidence against the type of objections resurrected here (Berman, 1993). I reasonably suspect that there are other elements of the Meditations which can be invalidated in this way without so profound an effect. However, these two objections undermine a critical, structural premise in the flagship proof of Descartes’ publication. Based on these two objections from Gassendi and the inadequate replies from Descartes, it is not clear or certain that Descartes ever possessed an idea of God containing infinite objective reality—the heart of premise five, as outlined in section one. If that is the case, then it no longer necessarily follows from his argument that God exists. In other words, Descartes’ proof for the existence of God fails. Berman, S. (1993). Infinite in Descartes [Dissertation]. Fordham University. Descartes, R. (2017). Objections to the meditations and Descartes’ replies, in the version presented at www.earlymoderntexts.com. (Original work published 1641). Kaplan, J. (2020, July 3). René Descartes – Meditation #3 – A cosmological proof of God’s existence. https://youtu.be/w4Kj6SuGYLo Moriarty, M., & Descartes, R. (2008). Meditations on First Philosophy: with selections from the objections and replies[EBook]. Oxford University Press. Smith, K. (2021). Descartes’ theory of ideas. The Stanford Encyclopedia of Philosophy, (Fall 2021 Edition). https://plato.stanford.edu/archives/fall2021/entries/descartes-ideas/ [1] Most references to Descartes’ Meditations on First Philosophy are from Michael Moriarty’s translation and will use the abbreviation “M” followed by the page numbers; where available, I will also cite the Adam & Tannery page numbers. References to all other works or editions will follow the APA 7th Edition format for in-text citations. |
