A PLATONIC ARGUMENT FOR THE IMMORTALITY OF THE SOUL IN CICERO (TVSCVLANAE DISPVTATIONES 1.39–49)

Abstract

An argument in Cicero's Tusculan Disputations (Tusc. 1.39–49) defends psychic immortality by reference to the physical constitution of the soul. This article argues that this ‘Physical Argument’ should be interpreted as a reception of Plato's doctrine of the soul within the philosophical paradigm of the Hellenistic era. After analysing the argument, it is shown that Cicero's proof recasts elements of Plato's Phaedo, in particular the kinship between the soul and the heavens and the soul's essentially contemplative nature, within a corporealist cosmology. The article also argues that Cicero formulates his argument to oppose the Stoic view that the soul's survival after death is only temporary. The Physical Argument emerges as a modernization of Platonic thought, putting Plato into dialogue with contemporary Hellenistic philosophy. Cicero, too, emerges as a more adept philosophical author than is often supposed.

The first book of Cicero's Tusculan Disputations (= Tusc.) is a riff on the ancient genre of consolation literature. Whereas some consolatory works aim to relieve the bereaved after the loss of a loved one, Cicero here aims to dissuade his interlocutor from his own fear of death (Tusc. 1.9).¹ Early on in the discussion, the question of the value of death gives way to a discussion of the nature of the soul: is the soul mortal or immortal? The work achieves its consolatory aim by working through this dilemma: either the soul is mortal or it is immortal; either way, death is not an evil. If the soul is mortal, then there exists no subject who would experience the evil of death. If the soul is immortal, then death is in fact a boon, and an eternal blissful life awaits.²

While the philosophical works of Cicero's late period (46–44 b.c.e.) are predominantly concerned with expounding and opposing the doctrines of the Hellenistic schools, this would not do for psychic immortality. In Hellenistic philosophy, the dominant sects were unanimous about the mortality of the soul: the Epicureans held that psychic atoms dissipate at death; the Stoics that, while some or all souls survive separation from the body, their permanence is ultimately temporary and they too will perish.³ Instead, Cicero credits the defence of the immortality of the soul to Plato (Tusc. 1.39, 1.49). Cicero offers some version of the Platonic doctrine of immortality in a number of works, most famously in the Somnium Scipionis,⁴ and the arguments of Tusc. Book 1 have a degree of overlap with these other discussions.⁵ Yet the exposition in Tusc. Book 1 is unique in the way in which it deploys these proofs and integrates the Platonic arguments into its specific dialogic and argumentative framework.⁶ For these reasons Tusc. Book 1 deserves a deeper examination than it has yet received. Tusc. Book 1 has been largely overlooked by all but the most dedicated source-critics, determined to find traces of Posidonius or Antiochus lurking behind Cicero's text.⁷ Moving beyond the source-question gives us a better appreciation of the unique argumentation of Tusc. Book 1, and thus a pivotal moment in the ancient reception and interpretation of Plato. (NB: I will refer to the author of the dialogue as ‘Cicero’, and to Cicero's dialogic avatar as ‘Marcus’.)⁸

Cicero presents Tusc. Book 1 as a companion piece to two Platonic works, the Apology and the Phaedo: the former provides the sceptical argumentative framework, while the latter is the locus classicus for Plato's defence of immortality.⁹ In this article I set aside Cicero's Academic-sceptical perspective and mode of composition.¹⁰ I focus instead on one particularly puzzling argument, which I call the ‘Physical Argument’ (Tusc. 1.39–49). The argument is puzzling for at least two reasons. First, it appears to attribute to Plato the doctrine that the soul is a corporeal substance with an elemental constitution, an attribution at which most interpreters of Plato, both modern and ancient, would likely demur. Second, the argument appears patently Stoic—Marcus mentions Panaetius by name (1.42)—while none the less arguing for the Platonic and un-Stoic conclusion of psychic immortality. I defend two claims in response to these apparent incongruities. First, the Physical Argument can be defensibly grounded in a reading of Plato, above all the Phaedo, within the theoretical milieu of the Late Hellenistic era. Second, the dialectical thrust of the argument is anti-Stoic: Marcus’ strategy is to argue that the Stoics, in light of their own philosophical commitments, ought to agree with Plato's doctrine of psychic immortality. In these ways the Physical Argument presents a modernization of Plato by bringing Platonic doctrine to bear on contemporary Hellenistic debates about the nature of the soul. By situating this argument within a contemporary dialectical context, the dialogue's return to Plato also marks the return of Plato to the philosophical fray.

I. A LATIN PHAEDO

Within the fictional narrative of the dialogue, the discussion is prompted by Marcus’ young interlocutor's, ‘A.’, fear of death (malum mihi uidetur esse mors, 1.9). Since death is either the separation of soul and body or the complete dissolution of the soul (1.18), the value of death and whether it is to be feared hinges on the nature of the soul. In his first pass, Marcus mounts a Socratic or elenctic refutation of the claim that death is an evil (1.9–18).¹¹ A. is unpersuaded, partly because he resists Marcus’ logical hair-splitting but more so because of his unshakeable attraction to immortality. A. signals this to Marcus, and in doing so Cicero signals to his readers the prominence of Plato in the discussion to come:

A. … in the first place I want this view [that we survive after death] to be so, and even if not, nevertheless I want to be persuaded.

M. So why do you need my work? Surely I can't surpass Plato in eloquence. Carefully read through that book of his, the one on the soul (qui est de animo):¹² you'll want for nothing more.

A. Dammit! I've done this, and many times over. But somehow, while I'm reading it I give my assent, but when I put down the book and by myself begin to contemplate the immortality of souls, all my former assent slips away. … Explain then, if you don't mind, first, if you can, that souls remain after death; then, if you fall short of establishing this (for it's difficult), please teach that death lacks all evil. For I fear this very thing, that it is an evil, and I don't mean that to lack sensation [is an evil], but the necessary prospect of lacking it. (24–6)¹³

A.'s request sets the template for the dialogue that follows, and Marcus will treat each horn of the dilemma—the soul is either immortal or mortal—in turn. The exchange also makes clear the importance of Plato, above all the Phaedo, in defending the first horn of the dilemma.¹⁴ The Phaedo is in many ways the Ur-consolatory text,¹⁵ and Marcus’ discussion directly and indirectly refers to the Phaedo throughout.¹⁶ But why does Cicero make A. a reader of the Phaedo? Gildenhard¹⁷ has identified here Cicero's spirit of cross-cultural rivalry: where Plato has failed to persuade, Marcus will succeed. But this overlooks the fact that Cicero presents Marcus as recasting Plato's own arguments for psychic immortality. This suggests that Tusc. Book 1 does not so much aim to supplant the Phaedo as to reframe and update Plato's arguments in a way that will be persuasive and effective for Cicero's contemporary audience.

Marcus’ three Platonic arguments are:

1. (i) Physical Argument (39–49)

2. (ii) Affinity Argument (50–70)

3. (iii) Simplex Argument (71)

It is fairly straightforward to discern the Platonic provenance of Arguments (ii) and (iii). In (ii), Marcus defends the immortality of the soul by likening it to god (Tusc. 1.50–1, 66, 70), recasting the Affinity Argument of the Phaedo (79e8–80a5).¹⁸ In (iii), Marcus offers an embellished translation of Socrates’ claim that the soul is non-composite (Tusc. 1.71 ~ Phd. 78c1–4). But the sense in which (i), the Physical Argument, can be considered Platonic is far less obvious.

II. THE PHYSICAL ARGUMENT

In the Physical Argument, Marcus argues for the immortality of the soul based on the soul's elemental constitution: the physical make-up of the soul guarantees its immortality. In this section, I offer an exegesis of the Physical Argument before situating it within its dialectical and interpretative context.

While Marcus attributes some of the cosmological details of the Physical Argument to certain mathematici (40), Cicero marks the proof as Platonic. Just as in 24–6, again Cicero dramatically motivates the introduction of Plato through A.'s Platonic fervour: A. would rather err with Plato than believe the truth with anyone else (39); Marcus approves of his enthusiasm (40).¹⁹ While the doctrine that souls are immortal was first advanced by Pherecydes and his pupil Pythagoras, the Pythagoreans failed to give reasoned argument (rationem illi sententiae suae non fere reddebant, 38–9).²⁰ It is Plato who, having studied in Italy with Pythagoreans, was the ‘first not only to believe in the immortality of souls but also to adduce arguments as well’ (primumque de animorum aeternitate non solum sensisse … sed rationem etiam attulisse, 39; cf. 49). The contrast is not merely between Platonic argument and Pythagorean authority (cf. Nat. D. 1.10). Indeed, Marcus asserts that, even if Plato had offered no proof, he would be compelled by Plato's authority alone (ut enim rationem Plato nullam adferret … ipsa auctoritate me frangeret, 49). Thankfully, this is not the case: Plato has offered rational arguments for the immortality of the soul (tot autem rationes attulit, 49). Dramatically, then, Cicero draws us away from both A.'s blind adoration of Plato and Plato's weighty authority to an appreciation of Platonic argument itself.

I now turn to the details of the Physical Argument. Marcus begins by stating some cosmological facts: earth is the centre of the universe, which is composed of four elements with natural motions each towards its natural place, earth and water downwards, air and fire upwards (40). The upward motion of these latter elements is due either to their inherent nature or else because of their lightness. These cosmological facts teach us about the soul:

(T1) Since these are agreed upon, it should be clear that souls, when they depart from the body, whether they are breathy, that is, of an airy nature, or fiery, are carried aloft. But if the soul is some sort of number (a view more subtle than lucid), or some fifth thing, unnamed but understood, then there are things even more pure and uncontaminated that carry themselves as far as possible from the earth. Therefore, the soul <is> one of these, so that so active a mind does not lie submerged in the heart, brain, or Empedoclean blood. (40–1)²¹

Marcus here does not advocate a single theory of the constitution of the soul but asserts a range of possible views: whether it is fiery–air, or quinta essentia, or even number, the nature of the soul carries it upwards. Why these three views? I suggest they all share two things in common.

First, these three candidates all originate in the thought of Plato's successors, at least according to the history of the Academy taught by Cicero's teacher Antiochus of Ascalon. Antiochus had claimed that Plato's successors in the Old Academy, the Peripatos and the Stoa all take their start from Plato himself, and are in broad agreement despite some minor doctrinal differences.²² The constitution of the soul is one such difference (Acad. 1.26, 39; Fin. 4.12–14). Aristotle advocates quinta essentia (Tusc. 1.22, 65–6 = Cons. fr. 21 Vitelli; Acad. 1.26; Fin. 4.12), Xenocrates number (Tusc. 1.20; Acad. 1.39; Luc. 124), and Zeno fire (Tusc. 1.19; Acad. 1.39; Fin. 4.12; Nat. D. 2.41). So, according to a prominent historical account of the Academy, all three views about the constitution of the soul have their roots in Plato's thought.

Second, the underlying thought behind these three views is that the soul's physical constitution must be sufficient to account for the activity of soul, which is treated as identical to mens (cf. Tusc. 1.22, 46, 66, 67, 70). Marcus here calls the mind uegeta, a word connoting specifically mental activity; later, the soul's swiftness is emphasized (43).²³ Thus, the constituent element(s) of the essentially active soul must itself be essentially active. The active nature of the mind is supposed to be sufficient evidence that soul is not to be identified with blood, the heart, or the brain. In both Stoic physics (SVF 2.418, 444) and the physics Antiochus attributes to the Old Academy (Acad. 1.26), fire and air are the active elements, and the Stoics emphasized the essential activity of fire (Nat. D. 2.41). Similarly, Cicero writes that Aristotle opted for quinta essentia because of the active nature of the mind (Tusc. 1.22, 65–6).

Xenocratean number is obviously the odd one out, as is reflected in Marcus’ apparent puzzlement (‘a view more subtle than lucid’).²⁴ In the earlier doxographical section, Marcus states that Xenocrates denied that the soul has any shape or corporeality but is composed of number, ‘since number had the greatest power (uis) in nature’ (1.20).²⁵ So Xenocrates too attributed to souls a composition that is essentially active. Marcus’ incomprehension seems to arise from two considerations. First, all of Cicero's reports of Xenocrates’ definition of the soul omit the claim that the soul is a self-moving number (ἀριθμὸν αὑτὸν κινοῦντα, Aët. Placita 4.2.1; see frr. 85–107 IP²). This omission, it seems to me, derives from a more fundamental philosophical problem with the view for Cicero, namely the incorporeality of number. On Antiochus’ account, Zeno rejected Xenocrates’ definition because only bodies can be causally active (Acad. 1.39); Cicero echoes this in his sceptical doxography on the nature of the soul (Luc. 124).²⁶ I suggest, then, that Xenocrates’ view is deemed ‘too subtle’ because it is unclear in what way number, even if it were an active force, can possibly account for the psychic activity of the soul. The soul must act and be causally efficacious, and in Cicero's Hellenistic milieu causal action requires corporeality. This in turn indicates that Marcus’ conception of the soul in the Physical Argument as essentially active correlates with the fact that he conceives of the soul as something material.

In the next stage of the argument Marcus reiterates the consequence of the elemental theory of the soul:

(T2) Now if the soul is of one of the four elements out of which everything is said to be made, it is made from heated air, as I think seems most commendable to Panaetius. By necessity it strives for higher regions, for these two elements have no share of the lower and always seek the higher. Therefore, if these elements are dispersed, this happens far from the earth, but if they remain and preserve their proper condition, it is even more necessary that they are carried towards the heavens. (42)²⁷

Marcus names Panaetius as advocate of the Stoic theory that the soul is made of pneuma. I will return to Panaetius in section IV below, but note here that the Stoic theory is none the less stipulated conditionally—if it is one of the four elements, it is fiery breath; this retains the possibility of Aristotle, or even (though less likely) Xenocrates, being right.

T2 highlights that the elemental argument leaves the conclusion underdetermined: there remain two live possible conclusions, namely that either the soul survives dissociation with the body but later dissolves or it remains forever (ita, siue dissipantur, procul a terris id euenit, siue permanent et conseruant habitum suum).²⁸ The latter is the Platonic conclusion of psychic immortality for which Marcus is arguing. The former is the Stoic view that all souls survive separation from the body, but do not persist eternally (cf. Tusc. 1.77–8).²⁹ So far then, the elemental argument can support either a Stoic or a Platonic conclusion, and it remains for the argument to defend psychic immortality over Stoic temporary permanence. That is what Marcus goes on to do:

(T3) When the soul reaches this region and is in contact with and recognizes a nature similar to itself, it settles among the fires composed from rarefied air and the tempered heat of the sun and ceases from its upward ascent. For when it has reached a heat and lightness similar to itself, held aloft in equilibrium no part of it moves, and at long last, when it penetrates to what is similar to itself, this is its natural seat. Here it lacks nothing and is nourished and sustained by the same things which nourish and sustain the stars. And since we are accustomed to be burned by the fires of the body and we are spurred towards nearly every desire … certainly we will be happy, when we are free from desire and jealousy with our bodies left behind. (43–4)³⁰

The soul's post-mortem permanence—rather than its belated dissolution—is defended by reference to the cosmological theory of natural place in conjunction with a particular moral psychology. When in the heavens, the soul is surrounded only by what is of the same nature as itself (sui simile). It is thereby devoid of destructive alien bodily influences and consequently free from anything that would cause its dissolution. Among what is akin to itself, it will cease its motion and be nourished by the same nourishment as the stars. So far, this is an argument from physics that could apply as much to fiery souls as to elemental fire. Marcus supplements this with a conception of the affections of the soul: since the soul is corrupted by emotion while embodied, when divorced from the body it will be free from these somatic corruptions. This emphasis on the freedom from bodily desire and emotion fits with the broader aims of the Tusculan Disputations, throughout which Cicero defends a broadly Stoic ideal of the extirpation of all emotions. Here, the freedom from psychic disturbance is not just the aim of human ethical pursuits, but the very fact that this is desirable while embodied is further proof that the soul will survive eternally intact after death. By combining the physical argument about the natural place of the corporeal soul with a moral psychology which emphasizes freedom from psychic disturbance, Marcus drives home the Platonic conclusion that the soul is immortal and rules out the Stoic alternative that disembodied souls only persist for a limited time in the heavens.

The proof ends with an elaboration of the activities in which the immortal soul will engage when disembodied:

(T4) What we do now when we are free from concerns, how we desire to look upon and examine things, we will do this even more freely then and will dedicate ourselves entirely to contemplation and understanding, especially because in our minds there is a natural insatiable desire to see the truth. To the extent that the borders of the regions to which we migrate makes this knowledge of the heavens easier to attain, so much greater will our desire for understanding be. This beauty, even on earth, excites that paternal and ancestral philosophy (as Theophrastus says), which is inflamed by a desire for thought. But theirs will be the highest enjoyment who, even while inhabiting this earth and engulfed in darkness, nevertheless desired to pierce through. (44–5)³¹

The human soul, Marcus claims, has a natural desire to see the truth. Since when embodied we turn to contemplation when we are free of earthly concerns (cum laxati curis sumus), all the more will the disembodied soul devote itself wholly to contemplation and investigation (totosque nos in contemplandis rebus perspiciendisque ponemus). While embodied we are limited, but when disembodied we will be able to attain a panoptic vision of the entire earth, its inhabitants and the heavens (45–7). Marcus adds a brief supplement on the mechanisms of the perceptive and cognitive powers of the soul (46): against a possible objection that the disembodied soul will be unable to perceive and contemplate without sense-organs, Marcus argues that ‘there is no perception in the body’ (neque est ullus sensus in corpore) but that the soul itself perceives through the sense-organs (animum et uidere et audire).³² The argument closes with a brief litotes: Marcus could continue to enumerate the marvellous sights and discoveries that await the soul in its natural abode (quam multa, quam uaria, quanta spectacula animus in locis caelestibus esset habiturus, 47), but this would go too far astray from the essential point of the soul's immortality.

So goes the Physical Argument. Marcus has not offered a complete account of the life cycle of the soul—for instance, he does not discuss how souls become embodied in the first place.³³ In line with the narrower consolatory aims of the dialogue, the focus is on eschatology and securing the soul's post-mortem permanence in the celestial realm.

III. A HELLENISTIC PLATO

The Physical Argument is proof for psychic immortality grounded in the physics and cosmology of the Late Hellenistic era. But while it comes to the same conclusion as Plato, in what sense can the argument itself be considered ‘Platonic’? Many of the details will strike readers as patently Stoic. We are left to wonder how Cicero could have believed that this kind of argument could be plausibly associated with Platonic immortality. I propose a two-part explanation. First, in Cicero's intellectual milieu, the fundamental approach of Stoic physics had become associated with the Platonic tradition as well. Second, once we realize the ubiquity of these shared commitments, we are able to read the Physical Argument as emerging from an interpretation of Plato's Phaedo within this contemporary paradigm.

Stoics held that the soul, god and the heavenly bodies are all made of pneuma or fire, and that human souls are fragments (ἀποσπάσματα) of god and so share the same pneumatic physical constitution.³⁴ Yet we have seen that Marcus does not solely report Stoic views (T1) but draws on the broader Platonic tradition, including Aristotle and the Pythagoreans. Within Cicero's milieu, a view similar to that of the Stoics had become common property among these schools. The Aristotelian notion of quintessence—largely absent from Aristotle, and surely not the physical constituent of the soul for him—rises to prominence among late Hellenistic Peripatetics.³⁵ Similarly the Pythagoreans are said to hold that souls are ἀποσπάσματα of aether (Alexander Polyhistor apud Diog. Laert. 8.28), and that our souls are ‘plucked’ (carperentur) from the all-pervasive world soul (Cic. Nat. D. 1.27). Relevant too is Antiochus’ conception of Old Academic philosophy. Antiochus claimed that the physical nature of the soul was a point of contention within the Old Academic tradition (Acad. 1.39; Fin. 4.12), but that by-and-large the Stoics and the Academics are in agreement about the most important aspects of physics (de maxima autem re eodem modo, Fin. 4.12). While Antiochus’ own position on the physical nature of the soul remains obscure,³⁶ his account of the physics of the Old Academic tradition are reflective of the broader trends in Cicero's philosophical milieu.³⁷ The predominance of a view of this kind is clear from Cicero's other expositions on the nature of the soul. For example, in the Somnium Scipionis the soul is composed of the same eternal fires as the heavenly bodies (Rep. 6.15).³⁸ We see, then, the ubiquity of the doctrine of a divine corporeal soul even within the Platonic tradition. What the Physical Argument does is argue from the physical constitution of the soul to its immortality. By framing this as a Platonic proof, Cicero brings Plato into the fold of Hellenistic thought about the nature of the soul.

Yet we would still like to find some sort of justification that renders the Physical Argument more than a mere retrojection of Hellenistic physics onto Plato. I think that, given this philosophical milieu and the ubiquity of the theory of a corporeal soul, the Physical Argument emerges as the result of an attentive reading of the nature of the soul in Plato's own works, in particular the Phaedo. To see this, let us look at two passages from the Phaedo which have close affinities to the Physical Argument:

(T5) But whenever the soul engages in investigation, itself by itself, it ventures there into what is pure and always existing and immortal and self-same. The soul, since it is akin to this, is always with this whenever it comes to be itself by itself and is able to be this way. And it ceases from its wandering and is in the same state with respect to the same things, because it grasps things of this nature. And is this condition of the soul not called wisdom? (Phd. 79d1–7)³⁹

(T6) The soul of the philosopher would reason in this way: it would not think that philosophy must free it, but nevertheless, once free, give itself over to pleasure and pains and bind itself down once again, working to no end like Penelope at her loom. Instead, the soul achieves a calm from these emotions, and follows reason and is always in reason, contemplating what is true and divine and removed from opinion. Nourished by this, it thinks that it ought to live in this way as long as it is alive, and when it dies, it will arrive at what is akin and of this nature and be freed from human evils. From this nourishment, Simmias and Cebes, there is no danger that one should fear that in separating from the body the soul would be dispersed by winds, blown apart and strewn about, ceasing to be anything anywhere. (Phd. 84a2–b7)⁴⁰

Socrates here recounts the nature of the soul, wisdom and the life pursued by the philosopher. I identify six key parallels with Marcus’ Physical Argument.

1. (1) The soul is naturally akin to the divine and heavenly. In the Phaedo, the soul is akin (συγγενής, 79d3; 84b2) to the eternal and the divine, and will arrive at and grasp (ἐφαπτομένη, 79d6) what is akin to itself after death (cf. 81a4–10).⁴¹ Marcus states that the disembodied soul will rise to its natural seat (naturalis est sedes) in the heavens, where it will ‘be in contact with and recognize a nature similar to itself’ (animus naturamque sui similem contigit et adgnouit, 1.43 [T3]).

2. (2) The soul ceases its motion in the heaven (πέπαυταί τε τοῦ πλάνου, 79d4–5; finem altius se ecferendi facit, Tusc. 1.43 [T3]).⁴²

3. (3) The soul is nourished in the heavens. For Socrates, this nourishment (τρεφομένη, τροφή) is achieved in contemplation.⁴³ Marcus claims that the ascended soul will be ‘nourished and sustained’ by the same things which nourish the heavenly bodies (T3). As a cosmological doctrine, this resembles the Stoic view that stellar bodies are nourished by the vapours from the earth (Diog. Laert. 7.145, Cic. Nat. D. 2.40). But note that Marcus here conspicuously does not identify the nourishment of souls and stars.

4. (4) For Socrates and Marcus, the soul's ascent requires release from desires and affections. At 81a–c, Socrates describes the soul's pollution by desires as being weighed down by the bodily and earthly, and so restricted from its ascent to the heavens.⁴⁴ As in the Phaedo, Marcus seems to identify the source of these pernicious desires with the body itself (corporis facibus, Tusc. 1.44; cf. Phd. 66b–e). Additionally, Marcus follows Socrates in employing the soul's freedom from desire as proof of its immortality. Socrates assures Simmias and Cebes that the nourishing effects of contemplation ensure the likelihood that the soul will not be ‘dispersed by winds’ (T6). Similarly, Marcus argues that the freedom from destructive affections ensures that the soul (qua elemental compound) will not be dispersed (dissipantur, 42 [T2]) far from earth but will remain intact. Here the Physical Argument mirrors not only the doctrinal content but also the argument itself.

5. (5) The disembodied soul will engage in perpetual contemplation.⁴⁵ This is because contemplation is the natural activity of the soul. Socrates asserts that what the soul does ‘itself by itself’ is its proper or natural activity (T5). Marcus follows suit and identifies contemplation as the activity of the soul on its own, without the need for body (46).⁴⁶ And just like Socrates (Phd. 114c), Marcus too demurs at explaining in full detail the soul's post-mortem life of contemplation (Tusc. 1.47).

6. (6) Both Socrates and Marcus insist that, even while embodied, humans should pursue this life of contemplation. For Socrates, this is what it means for the life of the philosopher to be practice for death (Phd. 67d8–9). Marcus later repeats Socrates’ sentiment (tota philosophorum uita … commentatio mortis, 1.74), and emphasizes that those who have separated their souls from the body through contemplation in life will have an easier ascent to the heavens (1.44–5 [T4]; cf. 75).

Cicero has fashioned Marcus’ argument with an eye to Plato's Phaedo. The significance of this lies in the fact that Marcus does not merely rehearse Socrates’ arguments. Rather, he integrates Socrates’ views on the essence of the soul into a cosmological argument about the physical nature of the soul. The Physical Argument transmutes the themes and features of Plato's text into the realm of Hellenistic physics and cosmology and situates this Platonic argument in the contemporary philosophical paradigm of the Late Hellenistic era.

IV. THE ANTI-STOICISM OF THE PHYSICAL ARGUMENT

I have argued that, despite its apparent Stoic features, the Physical Argument can plausibly be viewed as a refiguring of arguments from the Phaedo, ‘modernized’ for Cicero's contemporary audience. What would be the philosophical motivation for undertaking such an interpretation of Plato? One option would be to invoke Plato in support of Stoic philosophy. Panaetius is named explicitly in the argument (T2), and scholars have noted significant parallels with a Stoic theological argument found in Sextus Empiricus (Math. 9.71–4 = SVF 2.812).⁴⁷ We might suspect that the affinities between the Physical Argument and Stoic thought are a product of the supposed Stoic ‘rapprochement’ with Plato in the Late Hellenistic era.⁴⁸ But there are good reasons to resist this conclusion. Quite the opposite: I claim that the dialectical core of the argument is anti-Stoic, designed specifically to counter the Stoic account of the post-mortem impermanence of the soul.

We must first get clear on the Stoic alternative to Platonic immortality. Among those who take death to be the separation of soul and body, Marcus distinguishes three options (Tusc. 1.18): (i) the soul immediately disintegrates upon separation; (ii) the soul temporarily survives intact but eventually suffers dissolution; (iii) the soul remains forever. The first is the Epicurean view, the third the Platonic view, and the second the Stoic view (cf. 1.77).⁴⁹ But one might accuse Cicero of oversimplifying here, as the Stoic view is not univocal. While Zeno is reported to have claimed that the soul is long-lasting but mortal,⁵⁰ his successors disagreed on the extent of the soul's post-mortem survival. Diogenes Laertius (7.157 = SVF 2.811) reports that ‘Cleanthes holds that all souls continue to persist until the conflagration, while Chrysippus holds that it is only the souls of the wise that do.’⁵¹ The Chrysippean view dominates later doxography.⁵² Two further Stoic positions are relevant. Panaetius, although he denied the conflagration, none the less adhered to the line that rejects the immortality of souls.⁵³ Finally, Posidonius’ view on immortality has been a point of contention for interpreters, since he apparently claimed that ‘the air is full of immortal souls’ (plenus aer sit inmortalium animorum, Cic. Diu. 1.64 = fr. 108 EK). I follow the interpretation offered by Ju, who contends that for Posidonius souls are immortal (ἀθάνατος) in so far as they survive death (that is, the separation from the body), but are nevertheless perishable (φθαρτός) and so liable to dissolution: souls therefore will dissipate during (if not before) the conflagration, and it is only god or the world soul who can be declared both immortal and unperishing (ἄφθαρτoς).⁵⁴

Tusc. Book 1 completely fails to distinguish between these Stoic views. In particular, there is no mention of the different status granted to wise and non-wise souls, and any reference to the conflagration is conspicuously absent. That said, I do not think that Cicero's broad-brush approach seriously undermines his critical engagement with the Stoics. All these Stoic views agree in denying the eternity of souls and everlasting immortality to individuals. Given this underlying unity, I think it is justifiable for Cicero to paper over the details of the various accounts. The Stoics themselves admit that wisdom is vanishingly rare; since nearly every soul is non-wise, the special dispensation Chrysippus grants to the souls of the wise is moot.⁵⁵ In turn, this might justify the absence of the conflagration, since in practice the vast majority of souls will perish well before the conflagration.⁵⁶ In fact, one factor (but certainly not the only one) in specifically targeting Panaetius’ objections to immortality (1.79–80) may be that Panaetius is an example of a Stoic who denies the immortality of the soul on grounds irrespective of Stoic cosmological theory. Finally, it seems likely that Cicero, if he is sensitive to Posidonius’ distinction between immortal and unperishing, ultimately rejects this distinction.⁵⁷ The central conception of immortality in Tusc. Book 1 identifies immortality and eternity (aeternitas, 1.39, 50, 55, 80, 81), that is, eternal temporal permanence (1.18 permanare … semper; cf. 77 Stoici … semper negant). This identification is exactly what is denied by Posidonius’ distinction.⁵⁸ For these reasons, then, I think that Cicero is justified in treating the Stoic position monolithically as committed to the temporary permanence but ultimate destruction of the soul after death.

We can now return to the Physical Argument. Recall that at 1.42 (T2), Marcus teases the possibility of the Stoic conclusion only to resolutely deny it: the soul may persist temporarily only to dissipate later, but the natural affinity between the soul and the heavenly bodies and the soul's freedom from bodily disturbance prove that this cannot be so (T3). The implication of suggesting the Stoic theory only to deny it is that the Stoics themselves are guilty of the following error: their own theory of the physical nature of the soul and the cosmos is sufficient proof of the immortality of the soul, but they erroneously conclude that souls are subject to dissolution at some time after death. The Stoics by their own lights should agree with Plato but fail to do so.

This is exactly the criticism Marcus and A. raise against the Stoics later on. In maintaining that the soul persists after leaving the body, the Stoics assent to the most difficult part of the argument (quod tota in hac causa difficillimum est, Tusc. 1.78). But in asserting that souls nevertheless perish, they err in denying the logical consequence (quod … consequens) of their own view (Tusc. 1.78). Marcus then returns to Panaetius in order to draw the connection between this objection to Stoic psychology and the Stoic rejection of Plato:

Are we to believe Panaetius, when he dissents from his beloved Plato? For everywhere he calls Plato divine, wisest and most revered, the Homer of philosophers, but he does not abide by this one belief about the immortality of the soul. … He adduces a second argument: there is nothing that feels pain that is not also susceptible to sickness; but whatever succumbs to disease will also succumb to death; souls feel pain; therefore, they die as well. [80] These can be refuted: for they show his ignorance that, when the discussion is about the eternity of souls, we mean ‘mind’, which is always free from all disturbing motion, not the other parts [of the soul], which are subject to pains, angers and desires, which [Plato], against whom [Panaetius] is arguing, thinks are removed and isolated from the mind. (1.79–80)⁵⁹

Marcus mentions two objections to immortality levelled by Panaetius; my interest is in Marcus’ response to the second objection.⁶⁰ Marcus invokes Plato's tripartition of the soul, alluding to the theory of the Timaeus and the Republic that only the rational part of the soul is immortal.⁶¹ In the doxographical section, Marcus had already identified Plato's tripartite theory of the soul (Tusc. 1.20),⁶² and the proofs of immortality have focussed on the soul qua mens, that is, the rational soul. Since the rational soul is distinct from its irrational parts, it will be free from the destructive forces of pain and desire, and will survive permanently after its separation from the body. This reiterates the argument for the soul's eternal survival rather than merely temporary permanence advanced in the Physical Argument (T3).

Marcus’ response to Panaetius reinforces the anti-Stoic thrust of the Physical Argument. Recall that the broader argumentative aim of the dialogue is to demonstrate that, whatever the nature of the soul, death is not an evil. In principle, the mortality of the soul could serve this therapeutic goal, and indeed Marcus will go on to deploy a mélange of arguments concerning psychic mortality (82–111). The Stoic position alone is targeted for explicit refutation and is thereby flagged as especially deserving of reproach. The problem is that the Stoic position cannot convince us that death is not an evil because it is logically untenable. And it is untenable precisely because it does not agree with the necessary Platonic conclusion of immortality.

Panaetius, of all Stoics, is a fitting target for Marcus. The objections are not original to Panaetius,⁶³ but rather Panaetius is named as a representative of the broader Stoic position, as in T2 above. Panaetius had garnered a particular reputation as an ardent φιλοπλάτων, a Platonophile, as Philodemus calls him (T1 Alesse, Ind. St. LXI).⁶⁴ Here Marcus tells us that Panaetius calls Plato ‘divine, wisest and most revered, the Homer of philosophers’ (Tusc. 1.79), and elsewhere we learn that Panaetius ‘always had the names Plato, Aristotle, Xenocrates, Theophrastus and Dicaearchus on his lips’ (Fin. 4.79). By adhering to Stoic orthodoxy on the mortality of the soul, Panaetius is emblematic of the inconsistency which the Physical Argument imputes to all Stoics, rejecting Platonic immortality in spite of their own doctrines.⁶⁵

It is enticing to connect Marcus’ refutation of Panaetius with the reports that Panaetius labelled Plato's Phaedo inauthentic (νοθεῦσαι; frr. 146–8 Alesse). The details are obscure, but it is likely that Panaetius meant that the central thesis of the Phaedo—the immortality of the soul—was not a genuine Platonic view.⁶⁶ Marcus’ reproach turns the tables. Panaetius’ denial of the immortality of the soul becomes a mark not only of his philosophical ignorance but also of his misunderstanding his beloved Plato. I suggest that Marcus’ objection to the Stoics can be seen as a further intertextual nod to the Phaedo. Panaetius occupies the same philosophical position in Tusc. Book 1 as Cebes had in Plato's dialogue. Cebes’ famous ‘cloak maker’ objection protests that Socrates’ arguments prove only that the soul is long-lasting (πολυχρόνιον), not that it is immortal (Phd. 87b–88b). The long-lastingness of the soul is exactly the Stoic position (Stoici … diu mansuros aiunt animos, semper negant, Tusc. 1.77).⁶⁷ Cebes is a Pythagorean, and his incredulity at the immortality of the soul signals his inability to adhere to Pythagorean doctrine; he needs Socrates to convince him of his own doctrine, as it were.⁶⁸ So too here Panaetius, according to Marcus, ought to believe in the immortality of the soul both as a lover of Plato and as a Stoic. As Socrates corrects Cebes, so Marcus corrects Panaetius, and the Stoics in general, about their aberrance from Plato and the proper interpretation of their own doctrines.

V. CICERO'S PLATO

I have argued that the Physical Argument in Tusc. Book 1 is Platonic: Cicero presents a modern version of Plato, interpreted in light of, and in response to, the dominant philosophical paradigm of the Late Hellenistic era. This brings Plato into dialogue with contemporary philosophy, and in particular takes aim at the Stoics for their dissension from Plato. Marcus’ anti-Stoic strategy anticipates one that will recur in many of the Middle Platonists of the Imperial period: Marcus at once evokes Stoic doctrine only to undermine it by subordinating the incomplete and inadequate approach of the Stoics to a fuller and more consistent Platonic theory.⁶⁹ But there is a crucial difference between the Physical Argument and the strategies of later Platonists: Tusc. Book 1 does not advance the notion of an immaterial soul, but rather counters the Stoics within the Stoics’ own framework of psychic corporealism.⁷⁰

Finally, I have sidelined the source-question in order to give the Ciceronian material itself a fair shake. I do not wish to rehash the arguments pro et contra Posidonius or Antiochus or whoever as the source behind Tusc. Book 1.⁷¹ In fact, it seems to me that the source-question places the burden of proof in the wrong place, in so far as it assumes that Cicero needed a source. The dramatic unity of Marcus’ speech, especially his singling out of Panaetius (1.42; 79–80) and his advocacy for the life of contemplation (1.44–7; 74–5), speaks to Cicero's originality in crafting the argument. And the close parallels between the Physical Argument and the Phaedo suggest that, if we are so compelled to find a single source behind Cicero's argument, our best bet is to identify it as Plato himself. Tusc. Book 1 is a creative reinterpretation of Plato, and the Physical Argument has adapted and repurposed elements of the Phaedo to engage in the Hellenistic debate about the nature of the soul. Cicero, it seems to me, is the perfect candidate for this kind of creative reception of Platonic doctrine. Cicero was a product of his age, and he has presented a reading of Plato as a Hellenistic philosopher would. But being a student of one's age is different from being a slavish expositor of one's predecessors and I believe, barring any definitive evidence to the contrary, that the assumption should be one of Cicero's originality as a philosophical author.