Since duration is an attribute intrinsic to substance itself it seems to be located at a fundamental level of Descartes’ ontology. As such, it is a plausible candidate for being the type of time upon which motion depends. In my earlier analysis, I noted that Principles II.39 shows Descartes claiming that motion is dependent on some sort of temporal succession. Though noting this, I was not then able to identify what type of temporal succession motion requires (i.e., duration, time-in-thought, or the broader genus of time in general). Having now reflected on duration’s nature in particular, it is evident that duration offers the precise type of successive basis that would be a prerequisite for motion. Indeed, Descartes explicitly identifies duration with this sort of successiveness in his correspondence with Arnauld (29 July 1648).
I understand the successive duration of things in motion, and of the motion itself, no differently from that of things that are not in motion; for earlier and later in any duration are known to me by the earlier and later of the successive duration which I detect in my own thought, with which the other things co-exist.[20]
Descartes’ correspondence with Arnauld presents an account of duration that consistently ties together the various other passages that have been considered. First, it suggests that motion (either of bodies or—loosely speaking—of thoughts) is required for the conceiving of duration, but that it is ontologically irrelevant. Rule 12 indicated that duration, time, and motion were somehow tied together in such a way that the ideas of each were somehow implied by the others. The Arnauld correspondence explains this remark with regard to the relation between motion and duration. The concepts of duration and motion are tied together because motion makes duration knowable, whereas duration’s inherent successiveness makes motion possible. Duration can serve as the temporal basis of motion since duration is intrinsic to the very nature of a substance, and thus is never found separate from a substance that is in motion. Any substance that is in motion, insofar as it exists at all, has successive duration inherent in its nature. Thus, any substance in motion has its own intrinsic duration that can provide the necessary succession that enables the possibility of its motion.
There are additional reasons to suppose that Principles II.39 is claiming that motion is specifically dependent on the attribute of duration. In Principles I.57, when Descartes is explaining the distinction between duration and time-in-thought, it is duration that he identifies as being a feature of all movement. Recall that he explains that “the duration which we understand to be involved in movement is certainly no different from the duration involved in things which do not move.”[21] Accordingly, the duration of a motion seems simply to be the successive stages of a substance’s enduring, which are the prerequisite for the substance’s moving or changing. Though there can be no motion without the possibility of a substance enduring through successive stages, a substance will endure through successive stages (i.e., have inherent, successive duration) whether or not the substance has any motion. This interpretation explains both what type of time (i.e., successive duration) is required for motion, and why duration is not ontologically dependent on motion. Motion may make duration knowable, but there is duration whether or not it is known.
Though an analysis of duration explains the ontological and epistemic links between motion and duration, it is unclear how time-in-thought fits into this otherwise simple and consistent picture. By excluding time-in-thought from the discussion, one might have argued that “time” in Descartes is just the inherent succession of substances (i.e., duration), which is a feature that is both required for motion and likewise made knowable by motion. However, such an approach would miss the fundamental flavor of Descartes’ theory. Descartes offers not one—but two—different kinds of temporal attributes. Though the simple account from above explains certain fundamental features of Descartes’ account of time, the introduction of Descartes’ other temporal attribute (i.e., ‘time-in-thought’) obscures the picture. Unlike Descartes’ account of duration, the account picked out by time-in-thought is not explained by reference to the intrinsic structure of a substance, and it seems somehow to be dependent upon motion. Indeed time-in-thought is a much more elusive attribute than duration.
Part of the obscurity surrounding Descartes’ views on time-in-thought is that Principles I.57 defines it functionally. Time-in-thought is called the “measure of movement,” Descartes explains, when persons want to measure and compare the extent of various durations. He claims that durations can be measured when the extent of a thing’s enduring is compared against “the duration of the greatest and most regular motions which give rise to years and days,” and this is called “time.” Now that Descartes’ account of duration has been clarified, the reason why Descartes recognized a need for time-in-thought is quite evident. Since it has been shown that duration just is the inherent succession found in the very enduring of every substance, it follows that all substances have their own individual durations—the particular enduring of any given substance that grounds the possibility of that substance’s motions. As all durations are particular to individual substances, this account does not—by itself—suggest a universal sense of time.
Without the existence of some universal temporality, Descartes’ ontology would not admit of any meaningful way of comparing various durations, or even of answering the basic question, “What time is it?” As all durations are particular, if Descartes stipulated no temporal standard that could serve as the measure for all durations, then durations could only be compared on individual levels, according to the only weakly informative measure of faster or slower. If, for example, one were to compare the duration of finger taps on a desk against the duration of drips from a faucet, one could judge that there are four finger taps per single water drip. Though this would indicate a relationship between finger taps and drips, there would be no broader context according to which the taps or drips could be judged. One might conclude that there is a swifter duration between taps than drips (that is, there are more finger taps per drip), but the same judgment would be drawn in a comparison between finger taps and visits from Halley‘s Comet. Though a comparison could determine that there are many finger taps between each return of Halley’s Comet, judging that the duration of successive finger taps is shorter than either faucet drips or visits from Halley’s Comet is not terribly informative. Though returns of Halley’s Comet and faucet drips may share the slower than finger taps relation, this would provide scant means for organizing the world since no way of relating this information to things that have not been actively compared—like the durations of cat yawns, or drum beats, or camera clicks, and so forth, would thereby be determined. Rather than suggest that the world admits of only very incomplete and partial temporal organization, Descartes appeals to the regular cosmic motions as providing a standard against which all other durations can be compared. In doing so, Descartes makes his universal measure dependent upon motion in a way that duration is not.
Though Descartes’ reasons for appealing to the duration of the celestial motions to provide a standard measure are fairly straightforward, the nature of time-in-thought is not. One might have thought that time-in-thought has just been precisely defined as the duration of the regular cosmic motions insofar as they are employed to measure and compare all durations. Though such a simple account is appealing it does not cohere with Descartes’ clear contention that time-in-thought is “simply a mode of thought.”[22] If the attribute time-in-thought is distinguished from duration in general because it is simply a mode of thought, then it cannot be the case that time-in-thought refers to some extra-mental fact like the particular duration of the regular, cosmic motions. If time-in-thought is a “mode of mind,” then it must pick out something found in minds, not celestial bodies. As all modes of minds refer to the principal attribute of a thinking substance, time-in-thought must refer to some particular idea or act of thinking.
If time-in-thought must refer to an idea or act of thought, then one might suppose that time-in-
thought does not refer to the particular cosmic durations themselves, but rather to the idea that one extracts from this duration, or to the mental act of comparing this idea against the ideas one has of other particular durations. Though either of these possibilities may seem plausible insofar as they both are consistent with the “mode of thought” language, there are significant puzzles related to either alternative. First, there is the puzzle of determining which of these two apparent possibilities actually picks out the nature of time-in-thought. Second, there is the puzzle that either possibility supposes that time-in-thought does not pick out one thing. If time-in-thought refers to an idea that individuals are able to extract by observing cosmic durations, then it seems that there would be as many time-in-thoughts as there are minds forming these ideas. The same is true if time-in-thought refers to the act of comparing an idea of cosmic durations against ideas of other durations. According to either interpretation, there is no singular sense of time-in-thought. Instead, either interpretation supposes as many time-in-thoughts as there are minds conceiving or applying the idea of cosmic durations. As such, it is not clear how this multiplicity of time-in-thoughts could provide a singular, universal measure. As a way to begin clarifying these puzzles, I will briefly recall the temporal dualism of Francisco Suarez. As Suarez was a close contemporary of Descartes, if Suarez’s account shares significant, common elements with that of Descartes, then perhaps Suarez can help clarify Descartes’ account.
Descartes and Suarez
In chapter 1, I presented Suarez as offering a Dualist account of time. I there explained that Suarez argues for an account which posited two different kinds of time—intrinsic and extrinsic—with extrinsic time acting as the measure for intrinsic time. The first chapter additionally indicated that Suarez’s account was one with which Descartes was likely to be familiar since the view is presented in the Disputationes and Descartes makes explicit reference to the Disputations in his Fourth Set of Replies.”[23] In sketching Suarez’s account, the first chapter indicated how Suarez’s two types of times were not given equal ontological standing. Rather, Suarez identified his fundamental account of time with the inherent enduring of things—what he would frequently refer to as a thing’s “intrinsic duration.” This intrinsic duration was described by Suarez as being “not distinguished in a thing from the act of being of which it is the duration.”[24] Accordingly, Suarez’s intrinsic time is clearly very similar to Descartes’ account of duration. They both agree that duration is only conceptually distinct from substance. Moreover, just as Descartes credited motion with making duration knowable, Suarez credits motion with being the thing that makes his intrinsic time able to be conceived numerically.
It’s been noted that Suarez’s intrinsic time, that is, duration, is his fundamental temporal notion. As only conceptually distinct from substance,[25] Suarez locates intrinsic time at the ground level of his ontology. By contrast, Suarez’s “extrinsic time” is given a more derivative ontological status. As Suarez’s intrinsic duration is particular to enduring things, he posits extrinsic or “imaginary” time as offering an objective standard according to which these intrinsic times can be compared by one’s conceiving of these durations as filling up more or less of the imaginary time.[26]
Descartes’ time-in-thought bears a marked resemblance to Suarez’s imaginary time. Not only does Descartes appeal to time-in-thought in the same way that Suarez appeals to imaginary time (i.e., to explain how individual durations are measured and compared), but Descartes’ time-in-thought and Suarez’s imaginary/extrinsic time also both appeal to the cosmic motions to explain how this comparison is accomplished. Suarez argues that the imaginary time is able to provide an objective measure via an idea one originally forms of the intrinsic duration of particular cosmic motions.
We conclude that time is unique in the universe because it has its own meaning of extrinsic measurement, viz., in the movement of the heavens…Understood as an extrinsic measurement and as common to the other movements, it is taken partly from nature as it fundamentally exists, or inchoative (as I call it), and partly from a division through reason and an accommodation of it as a means of measurement.[27]
This passage indicates how Suarez takes extrinsic time to be an imaginary construct. Extrinsic time is a constructed idea insofar as it contains features not contained in the idea of the intrinsic durations of the cosmic motions themselves. Unlike the succession of the actual cosmic motions, the infinite succession supposed in one’s idea of extrinsic time is an idea of movement that is “continuous, successive, and non-repetitive.”[28] The idea that extrinsic time must be infinitely and non-repetitively extended is a requirement of its functioning as an absolute and objective standard against which any other duration can be contained and thereby measured. As the cosmic motions are themselves continuously repetitive, to form the idea of an infinitely non-repetitive succession, the original idea provided by the cosmic motions must be altered by one’s reason. This altering of the original idea is what Suarez explains as the idea forming “partly from a division through reason and an accommodation of [the duration of the cosmic motions] as a means of measurement.” The cosmic motions are thus able to offer a common measure for the measurement of all intrinsic durations provided that the idea of them is combined with the requirements conceived by reason.
In appealing to the cosmic motions as a standard by which intrinsic durations can be measured, Suarez’s account of extrinsic, imaginary time clearly resembles Descartes’ time-in-thought. As Descartes identified time-in-thought to be a “mode of mind,” time-in-thought seems even to share the mental component given in Suarez’s account of extrinsic time’s being an imaginary construct. As Suarez’s account of intrinsic time was likewise shown to closely correlate with Descartes’ account of duration, there seems to be good reason to suppose that Descartes’ account of time was inspired by Suarez’s account. Even beyond their resemblance, such a view is supported by correspondence between Descartes and Gassendi. In a letter to Descartes, Gassendi clearly identifies Descartes’ account of time with the sort of dualist account given by Suarez.
You mean to distinguish between external and internal time. But, if what I was talking about above is external time, what, then, is internal time? Let us take me for example. I am something that has already been in existence for fifty years which I know is the same duration as all other men of age. The count of the years that have passed since our birth is not the addition of as many times fifty years as there are of us quiquagenarians. It is only fifty years. Neither do I recognize nor do I learn from you how to distinguish in any essential ways, my fifty years of age, which are my internal concrete time, from the fifty years which have lapsed since my birth and which for you are external and abstract.[29]
In this passage, Gassendi is clearly presuming that Descartes holds some version of the Suarezarian dualist account of time. If Descartes’ own contemporaries interpreted his account of time in this way, then Descartes may have been knowingly and intentionally following the Suarezarian model.
Having compared the accounts of Descartes and Suarez, there is clearly a striking resemblance between the two. Since Suarez spent more time filling out the details of his account, it seems that Suarez’s theory might help inform an understanding of Descartes’. Though it cannot be assumed that Descartes’ time-in-thought agrees with all the features of Suarez’s extrinsic time, the similarities suggest a means of inquiry into time-in-thought. Specifically, it suggests that one consider if Descartes follows Suarez’s presumption that time-in-thought has a weaker ontological status than duration. To determine if this similarity obtains, it is necessary to understand the sort of “mode of mind” time-in-thought is for Descartes. Accordingly, this question will be the focus of the next chapter.
Conclusion
This chapter has resulted in several important discoveries. First, a resolution to Descartes’ seemingly inconsistent ways of relating time and motion has been determined; namely, it was determin
ed that Descartes can consistently maintain that time is dependent on motion and that motion is dependent on time because he posited two distinct types of temporal attributes (i.e., duration and time-in-thought). The former provides the successive temporal basis required for motion, while the latter depends on motion in some fundamental way yet to be determined. In attempting to clarify the individual nature of each of Descartes’ temporal attributes a third discovery was made; namely, that there are important similarities between Descartes’ account of time and that of Suarez. In considering Suarez’s account, one sees the immediate, historical precedent for Descartes’ temporal dualism. Moreover, the significant similarities between Descartes’ and Suarez’s accounts, suggest that Suarez’s extrinsic time might provide a model for conceiving of the elusive nature of time-in-thought. To determine just how closely the two views align, a deeper analysis of Descartes’ time-in-thought is needed.
Notes
1. AT VIIIA 64; CSM I.242.
2. AT X 421; CSM I.45–46.
3. AT VIIIA 27; CSM I.212.
4. Aristotle, The Complete Works of Aristotle, ed. Jonathan Barnes (Princeton: Bollingen Series, 1995). See: Physics IV.14.223a23: 377.
5. AT VIIIA 27; CSM I.212.
6. AT X 421; CSM I.45-6.
7. The Latin may be of some help here. The term here is ‘sive’ which is often used in early modern philosophy to indicate an identity (as in Spinoza.) However, sive is not always used in this way (even in Spinoza) and so it would be a mistake to automatically assume this sense.
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