Hobbes on Motion, Time, and the Structure of the Present Moment

1. Introduction

Hobbes is a presentist: he holds that only present things exist.¹ He grants that things have existed in the past and that things may yet exist in the future. He also allows that we can frame conceptions of such non-existent phenomena, picturing things as they might have been before they were annihilated or as they might yet come to be. Still, while our imaginations can range into the future and the past, existence itself is confined to the present.

But what, exactly, can exist simply in the present moment, neither spilling out into the future nor dragging in the past? On Hobbes’s own principles, it is not so easy to say. To begin with, he takes the non-existence of past and future beings to rule out the mind-independent reality of anything requiring past or future parts. On his own explicit account, this precludes the mind-independent reality of time. He might also seem, by strong implication, to take it to preclude the mind-independent reality of motion. And if presentism rules out the mind-independent reality of motion, it will also raise vertiginous questions about the material basis of thought, since thought itself is (according to Hobbes) just a particular kind of motion reverberating in the brain. These latter results are potentially destabilizing for Hobbes’s overall philosophical system. Motion in particular is a fundamental posit of his materialist metaphysics and natural philosophy. And, at least when he is not explicitly focused on the ramifications of presentism, Hobbes seems to assume that motion has a robust mind-independent reality and is not merely some sort of phantom appearance awkwardly complicit in the mundus imaginalis of the future and the past.

This puzzle has received little consideration from commentators.² I hope to show that it deserves our attention. I also propose a solution—a way of understanding the internal structure of Hobbes’s present moment that squares his commitment to presentism with his accounts of time, motion, and thought. The proposed solution is speculative in the sense that it is not one that Hobbes himself overtly advances. Nevertheless, I will argue that it is authentically Hobbesian in spirit. It applies Hobbes’s highly distinctive account of what it is to be an instant in time to the particular question of the present instant. My suggestion is that, for Hobbes, the present, like any other ‘Hobbesian instant’, lasts for some quantifiable period of duration, even as we systematically ignore that duration in thought and demonstration. On the proposed interpretation, Hobbes’s extended present moment can accommodate real mind-independent motion and thought, even as it cannot accommodate any real mind-independent time.

I suspect that some readers will regard the proposed cure as worse than the disease. That is their prerogative so long as they appreciate the interpretive costs on their own side of the question and do not simply sail past Hobbes’s presentist argumentation as if it were not there. While my interpretive hypothesis is fairly radical, it renders Hobbes’s presentism consistent with his other metaphysical commitments, which is more than can be said of any alternative reading that I can see. Moreover, I will argue that the proposal is not quite so bizarre as it might at first appear and that, once seen in a certain light, it both squares with Hobbes’s methodological thought experiment of the ‘annihilation hypothesis’ and anticipates in significant ways modern accounts of temporal experience and the phenomenology of the specious present.

2. Presentism and the Mind-Dependence of Time

Hobbes clearly and consistently endorses presentism. He asserts it quite plainly in Leviathan (1651/1668) and argues from it as an assumption in each of his natural-philosophical treatises, the unpublished manuscript Anti-White (composed in the early 1640s) and De Corpore (1655). I cannot see that he argues to it. Like nearly all philosophers before Einstein, he seems to have regarded the sole and exclusive existence of present phenomena as intuitively obvious and not itself in need of argument.³

In Leviathan, the doctrine appears as follows:

The Present onely has a being in Nature; things Past have a being in the Memory onely, but things to come have no being at all; the Future being but a fiction of the mind, applying the sequels [i.e., sequences] of actions Past, to the actions that are Present. (L 3.7)

The future might seem to come off the worst here, being reduced to a mere ‘fiction of the mind’, with future things ‘hav[ing] no being at all’. Rhetorically, at least, the past receives slightly gentler treatment. But it should not feel too comfortable about its situation either. Things past ‘have a being in the Memory onely’, which is to say that they too have no mind-independent existence, even if there are traces in our present memories from which we might frame conjectures about past phenomena. In fact, Hobbes allows that we can responsibly speculate about the course of both past and future events working simply from our current memories and current sense-reports (HN 4.7–8; L 3.7, 3.10). But neither past things nor future things exist anywhere ‘in Nature’ (or ‘in rerum natura’, L 3.7 Latin variant), which is to say, anywhere outside of the mind.

Presentism can be felt to be intuitive and commonsensical.⁴ But it can also generate philosophical puzzles, including semantic puzzles about the meaning, reference, and truth-makers of statements about the past and the future. By and large, early modern philosophers seem not to have worried overmuch about the semantic challenges to presentism, and Hobbes himself offers only a few passing remarks. He gestures toward an interpretation of talk about the future as expression of current predictions,⁵ and, as a strict determinist, might perhaps have held that the truth-makers for all statements about the future consist in facts about the present moment together with the general principles of motion and change.⁶

In Anti-White and De Corpore, presentism is deployed as an assumption in a pair of closely related arguments against the mind-independent reality of time. To understand these arguments, one has to appreciate that Hobbes takes it for granted that time is intimately connected with motion. Here (as we shall see) Hobbes is in line with Aristotle and the scholastic tradition. But he differs from later advocates of an ‘absolute’ time that, as Newton would put it, ‘of itself, and from its own nature flows equably without relation to anything external’, and hence, among the rest, flows equably without relation to the motion of bodies (1729: 1:9).⁷ By contrast, for Hobbes, as for Aristotle and the scholastics, motion gives us not just a practicable way of keeping track of time—as we trace days, hours, and minutes by the motions of the sun and the movement of sand through an hour glass—but provides us with our only intelligible conception of it. Indeed, when deploying this pair of arguments, Hobbes simply takes it to be uncontroversial that time either is constituted by the motion of objects or is a mental representation of such motion: that time either just is a matter of the motion of certain bodies, or that it is an idea or conception of the same. Since he regards these two models of time as the only live possibilities, Hobbes holds that if he can rule out the former option, then the latter wins by default: that, if time cannot be identified with the motion of bodies, it must instead be some sort of representation of motion in the human mind.

The argument in Anti-White runs as follows:

The definition of time ‘Time is the mental image of motion [motûs imago mentalis],’ can, I think, be gathered from many sources. First, if the nature of time consists in being some real succession, time would not exist. A real succession that has passed exists no more, because it has passed; and a future one does not yet exist, because it is a future one. There is no present save the instant, in which there cannot possibly be a succession. It remains, then, that time is not a motion in things themselves outside the mind, but is mere imagination. (AW 28.2, slightly adapted from Jones)

The last sentence confirms Hobbes’s overall strategy: once he has ruled out the identification of time with real mind-independent motion—with ‘motion in things themselves, outside the mind’—the only remaining alternative is that time is ‘mere imagination’. In order to rule out the identification of time with real mind-independent motion (‘motus’), Hobbes argues that there can be no real mind-independent ‘succession’ (‘successio’). Such a succession, he suggests, would have to include an ordered sequence of past parts or of future parts, or an ordered sequence of both. But, given presentism, no such past or future parts exist. Hobbes adds that there can be no succession in the present ‘instant’ any more than there can be in the (non-existent) past or the (non-existent) future—an assertion that will be of significant interest when we consider the structure of his present moment.

In De Corpore, the argument runs as follows:

[A] Moved Body leaves a Phantasme of its Motion, namely, an Idea of that Body passing out of one Space into another by continual succession. And this Idea, or Phantasme, is that, which [ … ] I call Time. [ … ] [A]s for those that say, Dayes, Years and Moneths are the Motions of the Sunne and Moon, seeing it is all one to say, Motion Past and Motion Destroyed, and that Future Motion is the same with Motion which Is not yet begun, they say, that which they do not meane, that there neither is, nor has been, nor shall be any Time: [ … ] What then can Days, Moneths, and Years, be, but the Names of such Computations made in our Mind? Time therefore is [ … ] a Phantasme of Motion. (DCo 7.3)

Again, Hobbes takes it that if time cannot be identified with real mind-independent motion, then the only remaining alternative is that it is a mental image (or ‘Phantasme’) of motion. And again we have the argument that, given Hobbes’s presentist rejection of past and future phenomena, there can be no past or future motion—that ‘Motion Past’ and ‘Future Motion’ are equivalent to ‘Motion Destroyed’ and ‘Motion [ … ] not yet begun’ (DCo 7.3). As previously in Anti-White, Hobbes also seems to be assuming that time cannot be identified with real mind-independent motion in the present any more than it can be with motion in the future or the past.⁸ And since time cannot be identified with real mind-independent motion either in the past, the present, or the future, Hobbes concludes that it can only be a phantasm of motion in the mind.

A word should be said about the difference here between Hobbes’s handling of time and his handling of motion. As we have just seen, both in Anti-White and in De Corpore, Hobbes advances an argument from presentist assumptions against the mind-independent reality of time. In each of these two arguments, the conclusion that time has no mind-independent reality is clear and explicit. That same thesis is also endorsed consistently within each work, and indeed it is part and parcel of his oft-repeated definition of time as a kind of idea, conception, or mental image (AW 28.1, 28.2, 30.5; DCo 7.3, 8.10, 12.4).⁹ By contrast, the thesis that motion has no mind-independent reality is not explicitly endorsed in either work. Perhaps it might seem to be implied, insofar as it might seem to be required for each of Hobbes’s demonstrations of the mind-dependence of time to go through. The thesis that motion has no mind-independent existence might also seem entailed by other explicit commitments in Anti-White and De Corpore, even if Hobbes neither registers it as an explicit conclusion nor rehearses the relevant commitments side by side. For instance, given his position that there can be no succession either in the past, the present, or the future (AW 28.2), it would seem to follow from his thesis that ‘every motion consists in a succession’ (AW 30.5) that there can be no real mind-independent motion. Or, again, the thesis that there can be no mind-independent motion might seem to follow from Hobbes’s explicit doctrine that there is no mind-independent time. After all, Hobbes tells us that ‘Whatsoever is Moved is Moved in Time’ and that ‘in every part of that Space in which Motion is made, we may consider three Times, namely the Past, the Present and the Future Time’ (DCo 15.1; see also 8.10). Motion here seems to unfold in time, in which case the non-existence of any mind-independent time might seem to guarantee the non-existence of mind-independent motion.

Hobbes’s treatment of time and motion is different in tone and substance, however. The thesis that time lacks any mind-independent reality is trumpeted in Anti-White and in De Corpore as the demonstrable conclusion of a set-piece argument. But Hobbes seems cagier when it comes to motion. Certainly, he never declares the mind-dependence of motion in the same direct way that he affirms the mind-dependence of time. And in fact, at other points in his works, he speaks of motion as if it were a real mind-independent property of real mind-independent bodies.¹⁰ This is not something that he ever does of time. As we shall see, this differential treatment is explicable under my proposed interpretation, for, on that reading, there is a sense in which real mind-independent motion is possible in the present even while real mind-independent time is not.

3. Aristotelian Time and the Threat of Anti-Realism About Motion

Hobbes’s basic line of argument from presentism against the mind-independent reality of time is not original to him. Aristotle outlines a version of the argument in his Physics, presenting it as a ‘consideration’ behind the ‘suspicion’ that time either does not exist at all or exists only in some ‘tenuous and faint’ way (1996: 217b32–218a3).¹¹ Aristotle leaves the issue as a puzzle, neither endorsing the argument nor proposing any specific way of resisting it. St Augustine also touches on the argument when documenting his own famous bafflement about time (1991: 231). And, as Pasnau (2011: 374–90) has shown, a considerable number of scholastic philosophers weighed this sort of challenge from presentism to the existence of beings with successive parts (or ‘entia successiva’), with time and motion serving as the two standard examples (cf. Edwards 2013: 176). That debate proceeded pro and con with particular vigor in the fourteenth century.¹² But it also surfaces in the works of sixteenth- and seventeenth-century commentators such as Suarez (1965: 2:956) and Geulincx (1999: 82).

Hobbes’s positive theory of time as a mental image of motion also has a connection with the Aristotelian tradition. In fact, Hobbes goes out of his way both in Anti-White and in De Corpore to point out that his account might be seen, from a certain perspective, as coinciding with Aristotle’s definition of time as ‘a number of change in respect of before and after’ (1996: 219a30). Aristotle’s definition itself presents thorny questions of interpretation, and different scholastic commentators had gone on to develop the formula in different ways. Some identified time with a mind-independent change or motion that could be numbered (i.e., quantified or counted), while others identified time with our mind-dependent numbering of that change or motion (Leijenhorst 2002: 128–31). Hobbes presents his own theory as a variation of the latter approach, and thus as a kind of ratification of Aristotle’s definition, at least if that definition is read in the latter, mind-dependent way, and if the mental operation of numbering is an operation of the imagination.¹³ Leviathan, especially, is well known for passages that perform a theatrically withering contempt for Aristotle’s philosophy. But Hobbes seems to be in earnest when he acknowledges Aristotle as a forebear on the nature of time. And Hobbes’s framing assumption that time must be either some kind of real mind-independent motion or a mental representation of motion does echo the traditional scholastic debate over the most plausible way to understand Aristotle’s account (Leijenhorst 2002: 131–37; cf. Edwards 2013: 166–68, 176).¹⁴

Hobbes’s conclusion that time has no mind-independent reality might seem to make for an awkward fit with his wider metaphysics, however. And if that anti-realism about time entails anti-realism about motion, it will seem especially threatening to what Brandt has called his ‘motionalist’ metaphysics and natural philosophy (1928: 379). The thesis that motion has no mind-independent reality appears quite at odds with the familiar picture of Hobbes as a robust realist who reduces all causation and all change to the motion of mind-independent material bodies. After all, Hobbes is clear and consistent that ‘all Active Power consists in Motion,’ reducing all causal activity to the motion of material bodies (DCo 10.6; see also DCo 9.7; AW 5.1). He is likewise clear and consistent that ‘all Mutation consists in Motion’, reducing all change to the motional reconfiguration of material parts (DCo 6.5; see also DCo 9.9, 25.2; AW 5.1). His natural philosophy, which is purged of all irreducible qualities besides magnitude and motion, is in fact simply a quantitative modelling of the principles of motion.¹⁵ And the motions in question are the motions of real mind-independent bodies, a system of external material objects presumed to exist outside the mind. Can Hobbes really hold that all this motion has no existence outside of the mind? In fact, the challenge to the traditional picture of Hobbes’s philosophy may be even more jarring. For Hobbes, mental activity and change, like all activity and change, is nothing more than the motion of material parts. All the various processes of sensation, imagination, thought, passion, and will are just one or another kind of motion in the brain, sense organs, animal spirits, and heart (AW 30.4, 30.5; DCo 25.2–8). And all such motions, however small or rapid, take some amount of time. We seem to be in danger of sliding into a uroboric paradox, in which the play of ideas in the mind is reduced to nothing more than the motions of material bodies in time, while time and motion and are in turn reduced to nothing more than a play of ideas. Where, here, is our footing?

4. Real Motion Outside of the Present?

To prevent the colors of anti-realism from bleeding across Hobbes’s motionalist metaphysics and natural philosophy, we need to show how real mind-independent motion can in fact be accommodated in his system. I will be arguing that Hobbes can place such motion entirely within the present moment, even as it cannot be located either in the (non-existent) past or in the (non-existent) future. Yves Charles Zarka and Geoffrey Gorham have each previously argued that Hobbes does in fact admit the existence of real mind-independent motion. But they have not restricted this mind-independent motion to the present, and either seem to have simply neglected the constraints on existence imposed by Hobbes’s presentism (Zarka 1996: 67), or have claimed that Hobbes is not consistently committed to presentism after all (Gorham 2014: 83).

According to both Zarka and Gorham, Hobbes’s treatment of time is best understood through an analogy with his treatment of space. Strictly speaking, space, for Hobbes, is a kind of phantasm, a mental image or mind-picture of the manifold of places that extended bodies outside of us might conceivably occupy—an imaginative representation, in effect, of the various ways in which extended bodies might possibly be distributed and redistributed.¹⁶ But it is a phantasm that is produced in the mind by our sensory encounters with real mind-independent bodies, which bodies do themselves have real mind-independent magnitudes—i.e., real sizes or extensions. The phantasm of space is caused by and in some sort correlates with these real magnitudes of real bodies. So, even though space itself is strictly imaginary and mind-dependent, there is a mind-independent system of extended bodies that gives our talk about space its purchase and utility. And in the same way (Zarka and Gorham suggest) Hobbes holds that, while time itself is strictly imaginary—a phantasm of motion and, perhaps, of the manifold of possible motions and hence the framework for all possible happenings—it is caused by and in some sort correlates with the real mind-independent motions of real mind-independent bodies. Thus, for Zarka,

It is important to appreciate that space and time are not particular phantasms among others, but belong to the form of our knowledge of existing and changing things. As time and space depend on our faculty of thinking, one can legitimately speak of the ideality of space and time; on the other hand, this ideality clearly has nothing transcendental about it, space and time have as correlates objectively existing objects, and are caused by the extension and motion of bodies. (Zarka 1996: 67)

Gorham also endorses a variation of this reading in the most comprehensive and detailed scholarly treatment of Hobbes’s theory of time to date. Indeed, Gorham goes so far as to say that Hobbes’s admission of mind-independent motion amounts to a commitment to a mind-independent ‘real time’ beyond the inner phantasm of ‘imaginary time’, just as Hobbes’s admission of mind-independent magnitudes amounts (as Gorham sees it) to a commitment to ‘real space’ beyond the inner phantasm of ‘imaginary space’.¹⁷ In this way, according to Gorham, Hobbes ‘ultimately does (and must) posit a real time that is independent of mind (though not of motion) just as real space is independent of mind (but not of body)’ (2014: 83; see also 103; see also 2017: 33).

So far as I am aware, Zarka does not acknowledge the threat to motion posed by Hobbes’s presentism. Nor does he address the question of where—in the past, present, or future—this real motion is to be located. This seems to me a considerable omission. In the case of space, there is no difficulty in our positing the corresponding real magnitudes. But in the case of time, presentism prohibits us from positing corresponding real motions, at least so long as those motions have any past or future parts.

Gorham does address the challenge to real motion introduced by Hobbes’s apparent commitment to presentism. His response is a deflationary reading of Hobbes’s presentist argumentation, at least as it appears in its ‘mature’ version published in De Corpore (Gorham 2014: 94). On Gorham’s proposed reading, Hobbes is not arguing that time itself (or motion, the objective correlate of Hobbes’s ‘imaginary time’) has no mind-independent existence, but only that the conventional divisions of time such as days, months, years, etc., have no mind-independent existence. As Gorham points out, Hobbes does introduce the argument in De Corpore as an attack on ‘those that say, Dayes, Years and Moneths are the Motions of the Sunne and Moon’ (DCo 7.3). So, Gorham proposes, perhaps Hobbes was merely addressing such conventional divisions of time, not undifferentiated time as it is in itself (2014: 99, 101–3). But this interpretation does not fit with the other parts of the text. Hobbes asserts, without any qualification, that ‘Motion Past’ is ‘Motion Destroyed’, not merely that conventionally divided past motions are motions destroyed. Likewise, in Anti-White, there is no indication that Hobbes means only to address conventionally divided time, or that his argument would not extend to any undifferentiated real time (or undifferentiated real motion) as it is in itself. And why would the presentist constraint on existence apply to time and motion only when they are divided up into conventional units? Hobbes’s presentism explicitly limits all existence to the present moment, and does not offer any special exemptions for phenomena that are free from mind-dependent division.

Before leaving Gorham’s reading, I want to add that, even if Hobbes does admit real mind-independent motion in his system—as I concur that he does—it is a distortion to present him as any sort of realist about time. Hobbes is absolutely consistent that time itself is only an ‘Idea or Phantasm’ (DCo 7.3). This mind-dependent account of time is rehearsed both in oblique argumentative contexts (AW 28.1, 30.5; DCo 8.10, 12.4, 26.1) and in his official, full-dress definitions (AW 28.2; DCo 7.3). It is never contradicted. Time just is a phantasm for Hobbes, and there is no talk about any ‘real time’ beyond this phantasm. The realist interpreter might insist that this internal phantasm is caused by and correlates with real mind-independent motion, so that there is a real mind-independent basis for our talk about time—in effect, a kind of ‘real time’, in spirit if not in letter, outside of Hobbes’s internal phantasm of ‘imaginary time’. But the whole point of Hobbes’s two arguments from presentism—each of which opens Hobbes’s account of time (the one in Anti-White, the other in De Corpore)—is to show that time cannot in fact be identified with real mind-independent motion, ‘that time is not a motion in things themselves, outside the mind, but is mere imagination’ (AW 28.2). Hobbes’s strategy in these two arguments is precisely to show that time can only be a phantasm in the mind because, given presentism, it cannot be identified with ‘motion in things themselves’.

5. Is the Present Extended?

I have been arguing that Hobbes means what he says when he confines all of reality to the present. However awkward it might be for his overall system, Hobbes holds that nothing requiring past or future parts can exist outside of the mind and its present-moment memories and prognostications.

If these are our cards, then a mind-independent basis for Hobbes’s metaphysics and natural philosophy can be sought only in the present. But what sort of phenomena might inhabit this precarious niche between the non-existent future and the non-existent past? How capacious, exactly, is the present moment?

On the face of it, it seems that Hobbes must regard the present either as extended or as unextended. Does he think of it as extended, i.e., as comprehending some quantitative period of duration, a genuine interlude, however brief, separating the past from the future? Or does he think of it as unextended—as a non-quantitative instant or zero-dimensional point-boundary at which approaching future events immediately touch the past as they pass over into it?

When the question is framed in these simple either-or terms, neither option proves textually viable. First, on any straightforward reading, the suggestion that Hobbes views the present as extended runs into significant textual problems. He is clear that any quantity can be divided into parts without end, and in particular that any extended period of time, no matter how small, is divisible into smaller and smaller segments (AW 2.1; DCo 15.2; see also AW 30.36; DCo 7.5). These parts will be successive rather than simultaneous, with some coming earlier than others, and others later. But since earlier segments of time are in the past relative to later segments, and later segments are in the future relatively to earlier segments, it is natural to think that two successive segments of time cannot both be in the present.¹⁸ At least, that is how Hobbes himself seems to parse the matter. He argues that any motion, no matter how small, takes some period of time, and that ‘in every part of that Space in which Motion is made, we may consider three Times, namely, the Past, the Present, and the Future Time’ (DCo 15.1). And in any period of time (no matter how brief) in which there is motion (no matter how small), we can discriminate the three tensed stages, so ‘that there can be no Conception of Motion, without conceiving Past and Future time’ (DCo 8.11). To judge solely by these texts, Hobbes’s present would seem to leave no room for any passage of time or any episode of motion, no matter how brief.

The suggestion that Hobbes views the present as unextended also faces textual objections of its own, however. First of all, if the present were unextended, we would have no hope of locating any real motion (which must, perforce, be real present motion) anywhere in Hobbes’s system. In his reply to Zeno’s arrow paradox, Hobbes makes it clear that to be in motion at all, a body must cover some space and take some time. No motion could exist only at an unextended present moment (DCo 8.11). Nor, if the present moment were unextended, could we extrapolate a body’s past or future trajectory of motion out from that body’s present-moment dynamical properties, for the only dynamical (or quasi-dynamical) property that Hobbes allows—‘endeavor’—is itself defined as a small but non-zero quantity of motion made in a small but non-zero quantity of time (DCo 15.2, 22.1). For Hobbes, there could be neither kinematic nor dynamical properties at an unextended present moment, and hence no real motion, nor any basis for real motion, in his presentist system.

Second, Hobbes holds that ‘there is no [non-quantitative or indivisible] thing in Nature’, and he explicitly applies this doctrine to rule out non-extended, zero-dimensional points, including both non-extended spatial points and non-extended ‘Instant[s] or Point[s] in Time’. In neither space nor time can there be anything that ‘has no quantity, or which cannot by any means be divided’ (DCo 15.2). Hobbes is clear that he is not rejecting the existence of either spatial points or temporal instants altogether. Spatial points and temporal instants are essential to his natural philosophy, and he offers us his own highly original account of how they are to be understood. But he is clear that these points and instants must have some quantity.

There are, then, serious textual problems facing any simple version of view that the present moment is extended and facing any simple version of view that the present is unextended. My alternative hypothesis is that Hobbes regards the present as an instant in the terms of his own distinctive account of what it is to be an ‘Instant or Point of Time’ (DCo 15.2)—an account on which an instant actually has some positive quantity and divisibility into parts, but in our reasonings is treated as if it lacked all quantity and divisibility.

6. The Present as a Hobbesian Instant

According to Hobbes, everything that exists in nature is a manifestation, in one way or another, of the system of material bodies characterized only by magnitude and motion. This is Hobbes’s strict autarky of extended, moving objects, where bodies are the only substances, and magnitude and motion their only irreducible accidents (DCo 8.1–3; see also L 4.21; L App 3.5–6). Points in space and instants in time must be accommodated either directly within this closed economy of matter in motion, or in our thought about it, with human thought itself understood as just another manifestation of matter in motion as physical reverberations echo through the human body and brain.

First, consider Hobbes’s account of what it is to be a spatial point in this purely materialist-motionalist system. A point in space, for Hobbes, is just a material body, whether real or imagined, that is considered in a certain way. We may reason about its position, movement, and distance relations to other bodies. But insofar as we are treating that body as a point, we will not consider its own magnitude (i.e., its size or extension) in our reasonings. The result is that any theorem that we prove about it will be generalizable to other similarly situated bodies regardless of their own particular magnitudes. Spatial points, like lines and surfaces, are (real or imagined) bodies that are considered in a certain way in order to produce theorems of general application. On this materialist conception, a point is not a zero-dimensional entity, but a three-dimensional concrete body, whether real or imagined, that is partially considered.¹⁹ Likewise, a line is not a one-dimensional entity, nor a surface a two-dimensional entity, but a three-dimensional body, some of whose dimensions are acknowledged in our computations, and others of which are systematically ignored.²⁰ In principle, the body that we treat as a point could itself be of any size. But in practice, we will want to picture a body whose own magnitude is negligible in comparison with the other quantities we are interested in, so that that magnitude can be easily bracketed in thought.²¹ In this way, an ink spot might serve as a point in illustrative diagrams in an ordinary-sized geometry textbook. And, while the entire globe of the Earth might also be properly regarded as ‘a Point’, treating it in this way is practical only when we consider its motion and distance relations in very large-scale circumstances, such as when we reason about ‘the Ecliptick Line’ that the Earth describes in ‘its yearly Revolution’ around the Sun (DCo 8.12).

Hobbes extends the same sort of analysis to the notion of ‘an Instant or Point of time’. He writes, in the immediate context of both spatial points and temporal instants, that

by a Point is not to be understood that which has no quantity, or which cannot by any means by divided (for there is no such thing in Nature); but that whose quantity is not at all considered, that is, whereof neither quantity nor any part is computed in demonstration; so that a Point is not taken for an Indivisible, but for an Undivided thing, as also an Instant is to be taken for an Undivided, and not for an Indivisible Time. (DCo 15.2, second emphasis added)

So, a ‘Hobbesian instant’ (as we might call it) just is some period of duration that, like all periods of duration, has some quantity or other, but a quantity that is systematically ignored, with the result that any theorems that we demonstrate about its relations to other instants and to bodies in motion are thus far generalizable. And, like any other period of duration, a Hobbesian instant is divisible (in thought²²) into parts, even while it is not actually divided.

My conjecture is that Hobbes regards the present as an instant in just this sense. Like any other Hobbesian instant, it ‘is to be taken for an Undivided, and not for an Indivisible Time’: it comprehends some period of duration, even while that duration is systematically ignored. Since Hobbes never offers an explicit account of the nature of the present moment, my proposal here can only be speculative and reconstructive. Still, there is significant circumstantial evidence in its favor, and I suggest that it has considerably more going for it than the rival interpretations of his present moment as either straightforwardly extended or straightforwardly unextended.

First of all, Hobbes speaks of the present as an instant. Recall: ‘There is no present save the instant [Praesens autem no est nisi instans]’ (AW 28.2). Admittedly, this explicit characterization of the present as an instant appears only in Anti-White, whereas Hobbes’s official account of the nature of instants does not appear until the later De Corpore. However, it is plausible that Hobbes was already thinking of instants in terms of the account subsequently set out in De Corpore. After all, while Anti-White offers no remarks specifically on the nature of instants, it does present Hobbes’s distinctive new account of the nature of spatial points, lines, and surfaces for the first time, insisting that they are not zero-, one-, or two-dimensional entities, but ordinary three-dimensional bodies partially considered (AW 3.8).²³ And, at least in De Corpore, Hobbes takes it to be perfectly obvious that what applies to spatial points here will also apply to temporal instants: that neither can exist without some quantity or other, but that in each case that quantity is systematically ignored in our thinking. No additional argument is given in De Corpore for the specific account of the nature of temporal instants, but only a reminder that there are no non-quantitative things in nature, and that what goes for spatial points will go equally for temporal instants (DCo 15.2). Most likely, then, Hobbes thought much the same in the earlier period of Anti-White, and in calling the present an ‘instant’, he did not mean to suggest that it was (per impossibile) a zero-dimensional, non-quantitative, indivisible entity, but rather only a Hobbesian instant, a divisible but undivided quantity of duration.

Second, if we take the present to be a Hobbesian instant, we can explain both those passages that imply that the present has some extension, and those passages that might seem to treat it as if it has none. On the one hand, since the present is actually extended and divisible, it can exist in a world in which all things have some quantity. It can accommodate real (present) motion and, hence, real (present) processes of thought, imagination, memory, and sensation. On the other, so long as we are thinking about this same period as the present—which is to say, as a particular kind of Hobbesian instant—we will be systematically ignoring its quantity and its divisibility into parts.

To specific texts. We can explain how it is that Hobbes might say that ‘there cannot possibly be a succession’ in the present (AW 28.2). Granted, the present is divisible, in thought, into any number of successive parts. But as soon as we start thinking about those parts, we are no longer treating the quantitative period of duration that we had previously called ‘the present’ as the present, but are mentally dividing it up. Moreover, given Hobbes’s ‘potential parts’ analysis of space and time, the parts into which the whole could be divided do not exist until it is so divided (Holden 2004: 96–99). Thus, in the specific context of space and time, ‘Nothing has Parts till it be Divided, and when a Thing is Divided, the Parts are onely so many as the Division makes them’ (DCo 7.9). A mental act of division is required to create the parts as so many distinct countable entities in the first place, and (hence) to create, if not the particular sequential ordering or successive arrangement that they stand in, at least the parts themselves that are successively so arranged.

We can also accommodate Hobbes’s assertion that thought about motion always involves thought about distinct tensed phases, ‘that there can be no Conception of Motion, without conceiving Past and Future time’ (DCo 8.11). Once we start to conceive of or think about the motion that unfolds within the extended ‘present’, we are imaginatively dividing that period into earlier and later stages, and discriminating relatively past and relatively future parts of that motion. But then we are no longer treating the period in question as the present, which is to say, as a particular kind of Hobbesian instant.

Third, we can also see how it is that Hobbes might take presentism to be at odds with the mind-independence of time while still allowing for the mind-independence of motion. Motion itself can exist in the present in a perfectly real and mind-independent way: it plays out within the extended and divisible present moment, even as we systematically ignore the extension and divisibility of the present in our thought and reasoning. But time, for Hobbes, essentially involves both our discriminating various successive parts within some instance of motion and our thinking of those parts as successive: it requires our imaginative attention to certain of motion’s distinct sequential stages, and our animadverting to the fact that some of those stages come before others while others come later. Hobbes is very clear on this point:

When I say Time is a Phantasme of Motion, I doe not say that this is sufficient to define it; for this word Time comprehends the notion of Former and Later, or of Succession in the motion of a Body, in as much as it is first Here then There. Wherefore a compleat Definition of Time is such as this, Time is the Phantasme of Before and After in Motion. (DCo 7.3)

Similarly, ‘Time’ is not simply an idea of motion, but rather ‘an idea of Motion in which we consider Former and Later, that is Succession’ (DCo 12.4, emphasis added; compare also AW 28.1, 30.5). For Hobbes, time just is this imaginative representation of the various parts of motion as sequential—this mental attending to the fact that certain stages come before others while others come after. But if the present is a Hobbesian instant, then we cannot imaginatively represent it (qua present, qua instant) as containing such successive stages of motion. We cannot mentally discriminate former or later parts of whatever motion in fact occurs within it. While real mind-independent motion can unfold in the present, time itself—that is, our imaginative attention to the successive parts of motion—cannot. Not, at least, while we are treating the present as the present, which is to say, as a particular kind of Hobbesian instant. Of course, should we go looking for the successive temporal stages in which any present motion unfolds, we can always find them. But then we will be considering that motion through a new imaginative representation—and are, in fact, imposing the parts-distinguishing and sequence-attentive idea of time upon it, creating the temporal stages that we ‘find’.

Fourth, this picture of a present moment that can accommodate real mind-independent motion even as time itself is a phantasm constructed in the imagination also comports well with Hobbes’s well-known thought experiment in which the external world is annihilated, leaving only a sole human survivor—a scenario in which neither any other material bodies nor (presumably, as usual) any past or future phenomena exist in nature. Hobbes posits that the surviving human would retain ‘Ideas & Phantasms, hapning internally in him that imagineth’ (DCo 7.1; see also HN 1.8; AW 3.1). This conscious inner life, with its ongoing ‘imagery and representation of the qualities of things without us’ (HN 1.8), serves as the starting place for Hobbes’s general metaphysics and natural philosophy, the beginning datum from which we can both ascertain the nature of space and time, and work out an empirically adequate account of the properties of outer bodies. Thus, even with the external world destroyed, the sole surviving human is still able to imagine different distributions of outer bodies, thereby revealing that space is an imaginative representation of the ways in which material bodies might variously be situated (DCo 7.2). In the very next paragraph, Hobbes argues similarly that time is an imaginative representation of the ways in which bodies might variously be moved—one that pays (as we have seen) particular attention to the successive stages of that motion: an ‘Idea or Phantasme’, picturing how a body might pass ‘out of one Space into another by continuall Succession’. All of these possible spatial and temporal orderings and arrangements are painted out in the imagination even while the world outside is annihilated, and even while all past and future motions have (as Hobbes explicitly reminds us) no existence in nature (DCo 7.3; see also AW 28.2). Still, the present imaginings of the mind are themselves real enough, and Hobbes insists that these inner imaginings are themselves so many internal bodily motions:

[T]ime is not a motion in things themselves outside the mind, but is mere imagination.

Let no-one interrupt here that ‘mere imagination’ is nothing; for imaginary motions, inasmuch as they are imaginary, do not have that existence that they seem to have. In someone imagining, however, they are real, for ‘the imagination of motion’ is the same as ‘motion in him who imagines’. So also a face appearing in a mirror is imaginary and real at the same time: an imaginary face, truly, but a real ‘imagination’; for the imagination is the real motion of the organ with which we imagine. (AW 28.2)

So, even with the presentist denial of past and future phenomena firmly in place, the present imaginings of the surviving human being—the methodological starting point of Hobbes’s natural philosophy, including his imagination-based framework of space and time—are processes requiring some ‘real motion’ in the brain. The present moment comprehends some real motion, even as it precedes the imaginative construction of both space and time.

7. How Long Does the Present Last?

On the proposed interpretation, the present comprehends some positive quantity of duration, even as we systematically ignore that quantity. But how much duration? How long does the present moment last? With no direct texts to guide us, here we can only ask about Hobbes’s best options.

One proposal that can be ruled out is the thought that Hobbes might treat the present as comprehending whatever quantity of duration we choose in the same way that other Hobbesian instants may be of any duration we choose so long as we systematically ignore that duration when reasoning about them. Granted, ordinary language permits an elastically extensible employment of ‘the present’. (‘I am away from the office just for the present, and will get back to you when I return.’) In appropriate contexts, ordinary language also permits elastically extensible present-tense talk about longue-durée states of affairs and processes. (‘In its mid-life phase, the Sun is a yellow dwarf star; later, it will turn into a red giant.’) But this elastic employment of ‘the present’ cannot give the sense at work in Hobbes’s presentist metaphysics. It would imply, absurdly, that the domain of existing things shifts and changes depending on whether we happen to be thinking narrowly or expansively about the range of the present. A version of our uroboric paradox would also return with a vengeance: our thoughts (like all other phenomena) can exist only in the present; and yet whether any given thought is in the present will depend on how expansive we are, in our thoughts (which can exist only in the present), about the range of phenomena we dignify as ‘present’.

The more plausible reading is that Hobbes’s present comprehends some fixed and determinate period of duration: some specific quantity that does not vary with human attitudes and thought, even as we ordinarily ignore that quantity and only in special circumstances would start to think about the various sequential stages of (real, mind-independent) motion that are in fact contained within it. Most likely, I suggest, this period of duration will be relatively short in human terms. Naturally treated as a Hobbesian instant, it should be some quantity that is easily ignored or bracketed out of everyday thought and reasoning—perhaps lasting no more than a second or so. We might think of it as a brief moment in which some sensible processes of motion and change could play out—perhaps long enough to hear a few notes of music, or to see a ball strike and shatter a window—while yet plausibly being experienced, phenomenologically, as an entirely contemporaneous present moment. In ordinary human experience, brief processes such as these can seem entirely present to current sensation, as belonging to a temporally immediate ‘now’ that is thought of as separate from even the recent past. At the same time, we can, of course, step back from this immediate phenomenology and intellectually appreciate that any such process, however rapid, could always be anatomized into a sequence of earlier and later stages. This account of the present moment as a kind of brief Hobbesian instant—a short interval that appears undivided, immediate, and fully ‘present’ to current sensation, but whose internal anatomy of successive stages could always be distinguished if we adopt a more intellectual view—has at least some similarity with the notion of ‘the specious present’ as articulated by the nineteenth-century psychologist E. Robert Kelly (widely known as ‘E. R. Clay’),²⁴ a phenomenological ‘present’ supposedly given in conscious experience, which feels simple and immediate even as it in fact comprehends a series of temporally distinguishable parts.²⁵ Of course, it is important to appreciate that Kelly regards the ‘specious’ extended present as merely a psychological phenomenon, whereas Hobbes’s extended present must exist independently of the human mind (on pain of uroboric paradox).²⁶ Still, the thought that the present has some brief duration and can encompass some processes of motion and change is not entirely unfamiliar.²⁷

If Hobbes’s present lasts for some determinate quantity of duration, why does it last for the particular determinate quantity it does? Why does it last for one second (say), rather than for two, or three, or a thousand? I see no obvious explanation, especially once we properly dismiss any explanatory appeal to human consciousness, sensation, and memory—processes that would themselves require the prior existence of real (present) motion. So here my interpretation does leave Hobbes with an arbitrary and unexplained commitment—or, at least, a commitment that I have not been able to explain. Perhaps the particular determinate size of the present moment is simply a brute metaphysical fact in his system. However, even at this cost, the proposed reading still seems preferable to the only alternatives that I can see. To review, those alternatives are: that Hobbes’s apparent commitment to presentism is merely specious, and may be discounted in favor of a silent but controlling commitment to the reality of past and future motion; or that Hobbes’s present moment is not a Hobbesian instant at all (with all the textual contradictions that entails); or that his present moment is a Hobbesian instant that can expand and contract with changes in human thought, thereby widening and narrowing the sphere of real existence and real (present) motion.²⁸

Competing Interests

The author has no competing interests to declare.