2.1 Taking a Step Back: The Word Nun in the Corpus Platonicum

The adverb nun, which the Greek-English dictionary LSJ renders as the “now, both of the present moment and of the present time generally” is used in the corpus Platonicum in a more general way (a), as well as in a rather technical way (b), which is my focus here.

1. a) Like the emphatic forms nundê (“just now”) and nuni (“just now”), nun is used to make the conversation now unfolding in the dialogues vivid.Footnote ⁵ Mostly, the nun refers to something punctual. This is best illustrated by a passage of the Phaedo, where Cebes recalls Socrates’ theory of recollection, according to which it is necessary to have learned (μεμαθηκέναι, perfect) in a certain previous time (ἐν προτέρῳ τινὶ χρόνῳ) the things that we now remember (ἃ νῦν ἀναμιμνῃσκόμεθα, present) (Phd. 72e5–7). The contrast being constructed is between a period of time in the past, in which learning as a process has taken place, and its result in the present (hence the perfect tense), when the punctual act of recalling happens. On many occasions, however, the nun conveys duration, rather than something punctual — I shall show at the end of Section 2.2 why this is problematic. A nun stretching for a while is best exemplified by expressions such as “all things which have been said just now.” Whereas, in the Parmenides, it refers just a few lines back (e.g., Parm. 130d8), in the Statesman “all things which have been said just now” (Pol. 286a7) encompass considerations expressed also in the Statesman’s prequel, i.e., the Sophist.

2. b) Nun is also used in a more technical sense, often in the phrase ho nun chronos, as occurs in the Philebus. In order to show that the soul experiences pleasure without the body (Phil. 34c 6–9), Socrates takes hunger and thirst both to be species of desire, namely a state of emptiness. Socrates begins by considering someone who is emptied for the first time, and gets Protarchus to agree that there is no way a person “could be in touch with filling, either through sensation or memory, since he has no experience of it, either in the present (ἐν τῷ νῦν χρόνῳ) or ever in the past” (Phil. 35a7–9, translated by Dorothea Frede; see Plato, 1997b). Here, the phrase ho nun chronos seems to refer to the present time generally speaking. In order to find a conscious technical treatment, we need to take into account the Parmenides, to which I will now turn.

2.2 Ho Nun Chronos in the Parmenides

Even in the Parmenides, Plato uses nun in a non-technical, more quotidian sense before assigning it a more technical sense. In doing so, Plato confirms his tendency to juxtapose more technical uses of terms usually taken to be metaphysically loaded — such as eidos and genos — with their respective conventional usages.Footnote ⁶

The first occurrence of the nun in the dialogue is to be found in the “narrative frame”Footnote ⁷ : Adeimantus tells Cephalos that Antiphon met many times with Pythodorus, who was present at the conversation between Socrates, Zeno, and Parmenides. Adeimantus tells Cephalos that Antiphon used to consider these topics assiduously, while now “he devotes most of his time to horses” (126c6–8). This nun is evidently protracted (as, for example, the translation of “these days” by Mary Louise Gill and Paul Ryan shows; see Plato, 1997a). A protracted nun also occurs in the dialogue between old father Parmenides and a young Socrates. Discussing the thorny question of which Forms exist, Socrates openly addresses the difficulty he faces and explains to Parmenides the way he found to cope with it (130d5–9). Parmenides attributes Socrates’ difficulty to his young age: after telling Socrates that “philosophy has not gripped you as it will in the future” (130e1–3), Parmenides adds that now Socrates still cares about what people think (130e3–4). Like the nundê, which Socrates has used a few lines before to refer to the things mentioned a moment ago (130d8), this nun (at 130e3) also extends over a period of time. As Parmenides will claim, a great deal of practice, which obviously requires much time, will be needed to overcome the actual state (135d2–6).

It is only in the second part of the Parmenides that the nun is also, although not exclusively, used in its technical sense. The technical sense is prominent in the first and second deductions. In the first deduction, the nun is characterized as the in-between member of the threefold ordered temporal series, pote — nun — epeita (i.e., at 141e3–7) which recurs later (i.e., at 155d1–3 and at 164a8–b1). The important point of the series is that, whatever direction we take, the order must stay the same; in other words, whatever direction we take, the nun will always be sandwiched between the pote and the epeita. A brief comment is necessary here on Plato’s choice of vocabulary. We get pote (— nun) — epeita, whereas the pair proteron — hysteron, which will be so important for Aristotle’s definition of time as the “number of change in respect of the before and the after” (ἀριθμὸς κινήσεως κατὰ τὸ πρότερον καὶ ὕστερον, Phys. IV 11, 219b1, Aristotle, Reference Hussey1983), occurs in our passage only in the coda, namely in relation to numbers (153b4–6), as well as in the exaiphnês-argument. The comparison with the pair proteron — hysteron is instructive. Even if pote and epeita are evidently related to one another, I do not take them to be relative terms in the way that proteron and hysteron are. Nevertheless, translating pote with “once” and epeita with “then” seems to me to miss the point conveyed by “heretofore” and “hereafter” (Turnbull, Reference Turnbull1998, ad locum) whereas the adverbs “once” and “then” can stand alone, “before” and “after,” qua prepositions, naturally demand completion (before/after what?), thus stressing their relation to the series comprised of pote — nun — epeita.Footnote ⁸ It is only in the second deduction, however, that nun is explicitly thematized and treated as a proper notion, as the nominalization witnesses.Footnote ⁹

2.3 The Temporal Notion of the Nun in the Parmenides

As I mentioned above, for a treatment of the notion of the nun, one must consider the passage 151e3–153b7. By way of introduction, a few words must be said about the argumentative context as well as about the structure and the premises of the argument.

The context. We are in the second deduction (i.e., 142b1–157b5) of the second part of the Parmenides, which is explicitly advertised as a dialectical exercise (135d7). Parmenides and his interlocutor Young Aristotle consider the consequences for the One in relation to the others if the One is, that is, if the One partakes of Being. I take this deduction, which is the longest of the entire exercise, to culminate in the so-called Appendix (155e4–157b5), for reasons I shall explain in Section 3.2.

The structure. The passage 151e3–153b7 can be divided into three main sections: the first section, i.e., 151e3–152b2, contains the premises; the second section, i.e., 152b2–152e10, presents the actual argument, and the third section, i.e., 153a1–153b7, can be regarded as a coda on difference, plurality, and things that have numbers. Since a shorter coda dealing with “being of the same age” can be also distinguished in the core argument (152b2–152e10), the true core of the argument, which I shall deal with extensively in what follows, is 152b2–d4. Before doing so, I shall briefly deal with its premises.

The premises. Parmenides begins abruptly with a quite condensed claim that works as an assumption for the argument, the logical steps of which can be identified by considering the interlocutor’s lines. Parmenides asks,

As the ensuing question of clarification (Πῶς;) attests, Young Aristotle takes Parmenides’ claim to be not entirely straightforward. Note that Young Aristotle voices a deep puzzlement precisely when the temporal aspect, which plays a pivotal role in the first two deductions, gets discussed (as his answers in the first deduction especially at 141d3 and 142a1 make manifest). Why? Here is my guess: because time is considered from a logical and not from the more familiar point of view, which is the empirical one. Even if change is the most incontrovertible phenomenon of our experience, the discussion of change is carried out on a purely logical level; in line with the (second part of the) Parmenides, the impulse throughout the passage is logical. To quote G. E. L. Owen, the problems are not “questions of empirical facts, but conceptual puzzles” (Owen, Reference Owen1986, p. 242).

This is confirmed by the architecture of the premises to be found in the section 151e3–152b2, namely (i) the distinction of present, past, and future (151e7–152a2), (ii) the introduction of the flow of time, and (iii) the direction given to such flow, namely from the pote to the epeita. Only after the three dimensions have been singled out,Footnote ¹¹ Parmenides adds the element of the flow of time. Notice that the argument gives the logical aspect absolute priority, since the element of the flow of time is specified only in a second moment and even then as a purely logical matter, namely without appeal to sense-experience. For only after inducing Aristotle to agree that the One partakes of Time, Parmenides adds “of the proceeding time” (πορευομένου τοῦ χρόνου) (152a3–4). What may sound like a trivial tenet, namely that time proceeds (προέρχομαι at 152b5) onward is far less trivial if we consider how the argument began. Whereas at 151e3 Parmenides’ initial compressed premise encompassed becoming both older and younger than itself and the others, for the most part of the core argument, the interlocutors deal with going forward κατὰ χρόνον, namely according to time or in time. This means to constantly (ἀεὶ) become older than oneself, which is according to the first deduction (141a 6–7), what it is to be in time, namely to partake of Time.

The core argument. What I consider to be the core part of the argument (152b2–e3) starts with a question, in which Parmenides drops the becoming older addressed so far and turns to the being older that becomes crucial in the central part of the argument (152b2–5). The One is said to be — no longer to become — older when it is in the nun chronos; the nun chronos is said to become the metaxu, the “was” and the “will be.” This is so (γάρ) because, moving forward from the pote to the epeita, the One will not overstep (ὑπερβήσεται) the nun (152b4–5).Footnote ¹²

While the basic idea could be expressed by saying that the One stops becoming older and is already older when the nun enters the picture, Parmenides almost intentionally plays with slightly different formulations, each of which seems not only to stress a different aspect of the same tenet but even to twist it, so that the reader wonders which formulation is the most “representative.” As is often the case in the passage at hand, the uncertainty arises because we cannot simply assume that a claim gets progressively refined. As we have seen before, it can happen that a quite compressed premise is then progressively explained, so that the most formally refined version comes at the beginning and not at the end of a line of reasoning. Here we are first told that it ceases to become older when it meets the nun and does not become, but already is, older (b6–c2); then that “if it is necessary that everything that becomes does not elude (παρελθεῖν) the nun, then whenever it is in it, it always ceases to become and already is that which it happens to become” (152c6–d2, my translation); and finally that the One, when in becoming older it has met (ἐντύχῃ) the nun, has ceased (aorist) becoming older and is already older (152d2–4). The second formulation (i.e., 152c6–d2) provides a third verb (παρέρχομαι) in addition to ὑπερβαίνω and ἐντυγχάνω. Notice that the verb ὑπερβαίνω is of extreme interest for the idea of the ordered series discussed above. In the sequel, we are told that the One meets (ἐντύχῃ) the nun, which is a formula that appears three times (152c1, 152d3, and 152d8) and seems to make the nun a sort of “gate” in the fixed route the almost personalized One must follow. Furthermore, the second formulation adds “whenever it is in it” (ἐπειδὰν κατὰ τοῦτο ᾖ), i.e., in the nun. One is made to wonder whether the three verbs (i.e., elude, meet, and not overstep) are functionally equivalent or whether one of the three captures more properly the problem at stake (and, if so, then, which one), the formulation “whenever it is in the nun” seems to ascribe to the nun a duration, no matter how short. We shall see why “being in the nun” is a problematic tenet.

Despite the emphatic “and thus” (Ἆρ’ οὖν at 152b6), it is difficult for the reader to understand how exactly Parmenides has drawn the inference that is precisely the tenet that, as we have seen, gets repeated with slight variations and additions throughout the passage: when the One encounters the nun, the One ceases to become older and does not become, but already is, older (156b6–c2). When the One meets the nun, there is no becoming older, but being already older — there is no process of change; change has already occurred; there is no process but instead a state, a result.

The process (of becoming) in which the One constantly is, needs to be stopped in a “snapshot” whenever the One “coincides with the present,” to quote Francis MacDonald Cornford (Cornford, Reference Cornford1939, p. 187). In what resembles a spatial treatment of time, such a reconstruction appears to be treating the One as a train which, in going, for instance, from Cologne to Bochum, will not overstep Düsseldorf, which lies between Cologne and Bochum. For a less spatial image, we might draw an analogy from music: there is no way to play the beginning of the Ode to Joy without playing a second E after the first one and before the F, which comes third. The E that is sandwiched between the opening E and the F cannot be skipped. Both examples evidently assume a continuum: just like the melody, which is not a series of impulses, the movement of the train is not a step-like progression. The train does not jump from one station to the next; the stations are merely arbitrary points along a continuous journey. Such points are indeed arbitrary, for while Düsseldorf’s main station is clearly in Düsseldorf, it is not obvious where Düsseldorf begins and where it ends. It is indeed a question of (setting) boundaries, as the central sentence shows:

To reconstruct Parmenides’ complex and condensed argumentation, I shall consider (a) the structure, and (b) the key terms of the key sentence, i.e., 152c2–6.

1. a) As for its structure, the key sentence consists of two gar sentences which purport to provide together the reasons for the claim made at the beginning of Parmenides’ line, namely that when the One meets the nun, the One ceases to become (older) and is already older. The second sentence is also supposed to ground the first one: each gar is a step back into the assumption of the prior sentence (van Emde Boas et al., Reference van Emde Boas, Rijksbaron, Huitink and de Bakker2019, 59.14). We thus witness a regress towards underlying conditions. In the first γάρ-sentence, the reason that the One must stop becoming when it meets the nun is presented in a counterfactual way: if it were moving forward, that is, proceeding in time, the One would not be caught by the nun (152c2–3). Note that the perspective has been altered, since it is now the nun that has the active power previously ascribed to the One. We learned that the One meets the nun and now we are told that the One is caught by the nun. Meeting the nun implies that the One moves while the nun does not; by contrast, being seized by the nun seems to make the nun, which chases the One, a moving entity as well.Footnote ¹⁴ The second γάρ-sentence specifies that what moves forward is such as to be in touch with both the nun and the epeita; what proceeds in time is said to depart from the nun, on the one hand, and, on the other hand, to reach the epeita while coming to be between nun and epeita (152c3–6). If my analysis of the argument’s structure is correct, then this is the key sentence:

1. b) The key sentence is puzzling in many respects. Terminologically speaking, the sentence is puzzling as far as (i) its subject, (ii) the verb used, (iii) the adverb metaxu, and (iv) the two elements that the metaxu connects, are concerned. Before dealing deal with these difficulties one by one in what follows here is the take-home message: since we are no longer dealing with the One, but rather with anything that becomes, Parmenides seems to be claiming that change as such has to take place between two contiguous nun, namely the nun, where no change can occur, and the epeita, a sort of nun in the future, where no change can occur either.

2. (i) The first thing to notice is the shift of subject: we are no longer talking about the One, but rather about that which proceeds in time (τὸ προϊόν at 152c3), which will then be referred to by the phrase “anything that is becoming” (πᾶν τὸ γιγνόμενον at 152c7). Thus, the conclusion seems not to be confined to the status of the One of the second deduction, but rather to encompass “anything that is becoming” and thus change in general.Footnote ¹⁵

3. (ii) What moves forward temporally is said to be such as to be in touch (ἐϕάπτεσθαι) with both the nun and the epeita (152c3–4). Within the same deduction, the entire section 148d5–149d7 has been devoted to showing that “the One has and has not contact (ἅπτεται) with the others and with itself” (149d5–6) and at least the following two connected aspects of this section are of interest for the present purpose: succession and neighbouring position. At 148e4–7, we learned that everything that is to touch something must lie next to that which it is to touch, occupying the position adjacent to that occupied by what it touches. In the aftermath, Parmenides added that that which is to touch must, while being separate, be next to what it is to touch, and there must be no third thing between them (149a4–6). Owen is right in pointing out that contact is defined in terms of succession (ἐϕεξῆς) and that contact requires immediate (εὐθύς) succession in the contiguous terms, since they must occupy neighbouring positions (Owen, Reference Owen1986, pp. 246–247). No third thing can lie between them (αὐτῶν ἐν μέσῳ μηδὲν εἶναι at 149a6). In our passage, however, what is in contact with both is also said to come to be between (μεταξύ) the two that are contiguous (152c5). This metaxu is key.

4. (iii) In our key passage, i.e., 151e3–153b7, metaxu, which will be key also in the exaiphnês-argument, recurs twice: what moves forward in time is said to become metaxu the epeita and the nun (152c5–6), whereas at the beginning the nun was said to become the metaxu between the “was” and the “will be” (152b4). As Spyridon Rangos convincingly argues, there are three entities that share the feature of being metaxu: the exaiphnês, which is metaxu movement (κίνησις) and rest (στάσις), as we shall see; the nun, which is metaxu “it was” and “it will be,” as we have seen at the beginning of the core section; and the proion, which is now said to become metaxu nun and epeita (Rangos, Reference Rangos2014, p. 550). As Colin Strang points out, the latter two cases of betweenness must be sharply distinguished (Strang, Reference Strang1974, p. 71): there is a becoming (γιγνόμενον) between the “was” and the “will be” (152b3ff.), and another becoming (γιγνόμενον) between the epeita and the nun (152c5–6). Whereas the metaxu of the nun explains its position in the temporal series, its being between the pote and the epeita, the metaxu of the proion explains when becoming takes place, namely between the epeita and the nun.

5. (iv) Note that what proceeds in time is said to be in touch (ἐϕάπτεσθαι at 152c3) not with the pote and the epeita, as one could expect from 152b4–5, but rather with the nun and the epeita. At the beginning the core passage, nun and epeita were characterized as neighbours in the series, that is, as contiguous. If this is so, then no third thing can lie between them. However, that is precisely what the end of the core sentence (i.e., 152b6–c6) implies by “coming to be between the two” (μεταξὺ ἀμϕοτέρων γιγνόμενον, τοῦ τε ἔπειτα καὶ τοῦ νῦν at 152c5–6). Directly after the nun, there can only be the epeita. As far as I can see, the only way to have a third thing between two adjacent things is to consider the limit at which the two things are in contact. Speaking of a “third thing” could be misleading, since that which moves forward is said not to be between the two, but rather to become between them. Is it then perhaps more appropriate to conceive the nun and the epeita as limits? Or is what moves forward becoming at the limit between nun and epeita? Proceeding in time is characterized as coming-to-be in between the nun, where no change can occur, and the epeita, which is a sort of nun in the future, that is, another moment/time/interval/limit (?), where change cannot occur but has already reached its telos, its completion. Along these lines, nun and epeita would be the beginning and the end of a duration, and thus its limit (πέρας) according to Parmenides’ dictum in the first deduction (Καὶ μὴν τελευτή γε καὶ ἀρχὴ πέρας ἑκάστου at 137d6).

The textual analysis gives rise to far reaching problems as far as the ontology of the nun (and ontology only, since nothing is said in the passage about how we get to know the nun) is concerned. The claim that what becomes has to leave the nun, in which Becoming cannot take place, to reach the epeita, may invite one to take the nun as limit (peras): the nun and the epeita would limit, at the beginning and at the end, respectively, Becoming qua duration. As far as the Parmenides is concerned, taking the nun as limit is problematic for at least two reasons: (i) taking the nun as limit would lead to an internal inconsistency, since whereas a limit has no extension, a chronos understood as time interval does; (ii) taking the nun as limit would also make it exaiphnês-like, if we also take the latter as peras, thus questioning the raison d’être of two distinct temporal notions with the same function in the same dialogue. Furthermore, but that goes beyond the Parmenides; if taken as limit, the Platonic nun would come close to the Aristotelian homonym, which notably is an extensionless boundary between past and future.Footnote ¹⁶

1. i. As we have seen, Parmenides begins with ho nun chronos.Footnote ¹⁷ Because of the term “chronos,” one could wonder whether the nun should be conceived as having a certain duration. According to Strang (Reference Strang1974, p. 73), precisely the use of “the now time” strongly suggests that a now has a duration. Along these lines, the nun would have to be conceived as an interval of time. Turnbull compares it with a non-technical use of now, which I have been exploring in the first part of the article; this now is “‘lasting’ a little while” (Turnbull, Reference Turnbull1998, p. 108). There are good arguments to challenge the view that the nun can or does in fact endure. According to Rangos, only an indivisible present conceived as (a) an atomic unit of time, or (b) an unextended boundary can satisfy the requirement of the argument according to which in the nun becoming is impossible. What lasts must have a duration, however short — something that a limit qua limit cannot have (see, e.g., Sattler, Reference Sattler2020, p. 235).

2. ii. Interpreting the nun as limit would also make it exaiphnês-like, if, of course, we interpret the Platonic exaiphnês as an extensionless instant. If both notions refer to durationless limits, one could feel invited to assimilate them into one single notion. I shall provide some reasons for avoiding this interpretive move in the next part of the article.

3.1 The Imperceptible Exaiphnês

Before turning to the exaiphnês-argument in order to clarify how it could interact with the notion of the nun, it will prove useful to consider an often neglected passage of Aristotle’s Physics where both the nun and the exaiphnês are unexpectedly addressed. It is well known that Aristotle’s nun plays a crucial role in his account of Time in the Physics, since “it is impossible for time either to exist or to be conceived without the now” (Phys. VIII 251b19–20).Footnote ¹⁸ The “treatise” on Time in Book IV of the Physics (IV. 10–14) contains a passage that almost always goes overlooked. In a small “dictionary” of temporal notions, Aristotle considers the nun together with τὸ ἐξαίϕνης, τὸ ἤδη, τὸ ἄρτι, and πάλαι (with no article). The extremely condensed passage reads as follows:

Aristotle connects the brief account of the notions of “the just” and “the recently” to our customary usage by means of a (fictive) dialogue.Footnote ²⁰ Whereas Aristotle’s interest in what could be labelled as everyday language is widely known, the dialogical framework with the structure of question and answer tends to receive less attention. Whether we are entitled to see a Platonic echo in this interrogational model is a question I shall leave open. Strictly speaking, the exaiphnês is detached from the conversational framework. However, the definition of the exaiphnês is given as though Aristotle were continuing what Plato’s Parmenides started, yet doing so — as is often the case for Aristotle — in polemical terms. It is perhaps a kind of meta-dialogue. As we shall see, the definition of the exaiphnês is given in Platonic terms because the Platonic exaiphnês is individuated by its detachment from time (ἐκστάν is the word chosen by Aristotle). In his own treatment, however, Aristotle adds the aspect of the perception of time (as marked by ἀναίσθητος), which is precisely what Plato’s Parmenides avoids. Yet, being imperceptible is precisely what allows Parmenides in the eponymous dialogue to give the exaiphnês the logical role required by the argument at hand. Let’s see what I mean by that.

3.2 The Exaiphnês-Argument in the Parmenides

Before offering some arguments as to why it makes sense to keep both notions distinct, I shall reveal my cards as far my reading of the exaiphnês-argument, the so-called Appendix of the Parmenides (155e4–157b5), is concerned. I take both the nun passage and the exaiphnês-argument to belong to the same deduction, to which I limit myself in this article.Footnote ²¹ As in many other places in the corpus, also in the Parmenides, the adverb exaiphnês is used to underlie that something of importance happens suddenly — the first place that comes to mind is surely the sudden vision of Beauty in the Symposium, where the kind of understanding or vision which results from a step-by-step process is said to happen exaiphnês (Symp. 210e4).Footnote ²² As for the Parmenides, I take the kind of μεταβολή addressed in the passage 155e4–157b5 to be a “switch” or a “jump” or “leap” (Gr. ἅλμα) from one state to the other,Footnote ²³ call it F and not-F, where F and not-F are “mutually exclusive and jointly exhaustive opposites.”Footnote ²⁴ The focus of Plato’s Parmenides in this passage is motion (κίνησις) and rest (στάσις), which are also considered enantiotata (most opposite) in the Sophist (Sph. 250a8–9).Footnote ²⁵ I take the Law of Non-Contradiction and the Law of Excluded Middle to be not only assumed, but even stated within the argument.Footnote ²⁶ Yet, the argument does seem to me to reintroduce the contradictory situation for whose avoidance time itself, that is, the temporal distinction, had been introduced by assuming that there is no time in which something is neither F nor not-F simultaneously (ἅμα at 156c6–7). Given that a shift from F to not-F or vice versa is needed, and given that “there is no time in which something can, simultaneously, be neither in motion nor at rest” (156c6–7), one could still have some reservations as to whether the exaiphnês-argument hits its declared target, which is to answer the question of when the change occurs.

3.3 How the Nun and the Exaiphnês (Could) Interact

In the nun passage, we learn that becoming does not occur at the nun. If change cannot take place in the nun, because in the nun what is becoming stops becoming and is already what up to that point it has been becoming, when does it become? Between the nun and the epeita, as we have been informed; en tô exaiphnês if we trust the conclusion of the exaiphnês-argument. Yet, if time were made up of nun only, then there would be no change — perhaps good for the historical Parmenides, yet less good for Plato, who has never abandoned the view that physical objects are always changing.Footnote ²⁷

Nun and exaiphnês as functionally equivalents. Even if I take the nun and the exaiphnês to be distinct, it proves useful to begin by considering the opposite claim, namely that the two notions are, or at least work as, functionally equivalent in two distinct albeit closely related arguments. Since the nun almost disappears after 153b and since the exaiphnês is entrusted with the role of explaining when change occurs, some scholars suggest subsuming the former notion under the latter one.Footnote ²⁸

Nun and exaiphnês are different answers to different questions. To explain how the two notions are to be distinguished, some scholars have argued that they are intended to answer totally different questions. For the two notions are too disparate to answer the same question. In support of this claim, first consider the different way in which the nun and the exaiphnês are introduced in the dialogue. Whereas the exaiphnês receives a proper, albeit condensed, introduction by means of the emphatic question “does this out-of-place thing then exist, in which the One would be when it changes?” (156d1), the nun is not properly introduced. Some interpreters explain such non-introduction by claiming that the nun is somehow ready at hand, an “old familiar,” as Strang puts it (Strang, Reference Strang1974, p. 73). By contrast, the exaiphnês is famously characterized as something atopon, literally out-of-place, “absurd” or “beyond our reach,” namely something very much out of the ordinary becoming-in-time which we experience.

Same issues at stake, different notions. Even if different, I take the nun and the exaiphnês to be related to the same issue, namely making sense of Becoming. Here is why. The nun passage opens with Becoming (γίγνεται at 151e3–4) and by the end the initial One is replaced by “anything that is becoming” (πᾶν τὸ γιγνόμενον at 152c7). Becoming is explicitly singled out as the problem at stake within the exaiphnês-argument (γίγνεσθαι at 156a5), for there, motion and rest are chosen not to delimit, but to exemplify the underlying problem of everything that switches, namely the question as to when (we can say that) what switches switches. In both passages, what is at stake is Becoming.

In the nun passage, we learn that becoming does not occur at the nun. Since becoming cannot take place in the nun, because in the nun what is becoming stops becoming and is already what up till then it has been becoming. “So when, and how (comes the insistent question) does the moving get done?” (Strang, Reference Strang1974, p. 68). “The moving” gets done in the exaiphnês as well as between the nun and the epeita. Thus, if an equation can be established, then this equation would not encompass the exaiphnês (which has an in-between nature) and the nun, but the exaiphnês and what is in between the nun and the epeita. We shall see why even this equation should be rejected.

Combining switch and continuous change. To square the two tenets, namely (i) that shift from F to not-F occurs in the exaiphnês, and (ii) that everything that becomes, becomes between the nun and the epeita, I can see only two options, both of which face difficulties.

1. a) One could take the process of becoming as a duration, the beginning of which is marked by the nun and the end of which is marked by the epeita, which looks like the nun after or next to the actual nun. Since becoming is banished from both the starting nun and the ending epeita, we would need the exaiphnês to make the switch from the nun/epeita conceived as a static limit and the duration limited by the nun and the epeita.

1. b) One could take each nun to be a sort of snapshot where everything has to stay at it is, and the flowing time to be a series where one nun comes after the previous one. The temporal sequence would then consist of units. Each unit would not allow to being further divided, since if it were divisible, one could run into the following problem: if we can divide the temporal units into subunits, there will always be a before and an after within the divisible unit so that the nun will disappear. Jerking from nun 1 to nun 2 (the latter of which one could also call epeita), that is, a first snapshot where I have only one wrinkle to a second snapshot where I have two wrinkles, would require the intervention of the exaiphnês. The exaiphnês, which would work as the glue to keep one nun connected to the next, would guarantee that something changes between the nun and the epeita.

More basically, then, I take both models to be flawed because they aim to combine the exaiphnês and the nun. As a last step, I shall show why it is more fruitful to keep them apart.

Switching outside of time, Becoming within time. Both models discussed above aim to combine the exaiphnês and the nun within one model that integrates both of them. Having shown why both attempts to combine them fail, I shall now suggest a two-models model.

A two-models model could be conceived as follows. One could argue that the exaiphnês and the nun refer to different levels. Whereas “the now excludes becoming and by so doing it excludes any possibility of change” (Rangos, Reference Rangos2014, p. 546), the exaiphnês could be said to be the condition of possibility for change as such. One could also argue, as has been done, that each of the two notions refers to a different aspect of the same entity (Rangos, Reference Rangos2014, pp. 521–522) or that the two notions explain change from two different ontological perspectives, or as far as ontologically different realms are concerned. It has been argued, for instance, that whereas the nun explains change in the sensible world, the exaiphnês explains “change” as far as it “concerns” changeless Forms. The exaiphnês would explain participation in different Platonic forms, whereas the nun would describe the transition in the sensible world. For while participation changes instantaneously, sensible change is a process. In what follows, I shall develop an intuition along those lines, while leaving both Forms and the thorny issue of participation aside. By focusing on sensible entities only, I suggest a two-models model in which what differs is not the level or the ontological perspective, but the kind of change.

The kind of metaballein referred to in the exaiphnês-argument is not a process, like aging, but a switch.Footnote ²⁹ By contrast, the becoming-older addressed in the nun passage develops gradually. In the former, we have change seen as the jump from one state to the other. The exaiphnês is introduced to avoid a contradiction in switching from F to not-F, as the paradigmatic case of rest and movement shows. Yet, not all change is of this type. There is also a change understood as progressive becoming. There is no jump in becoming older and older and older. The key is the comparative to which Parmenides sticks in our passage.

The nun does look like a relative in the sense that it requires another nun to which to refer in the comparative: I am older now than I was a moment ago. The nun is this present is in relation to the past. Even if it stops becoming, the nun is in time. It is a part of time. Whereas the exaiphnês lies outside of time, the nun is part of the time series pote — nun — epeita. The two notions have a different relation to time: the nun is in time, always in process, but as a snapshot; that is, as a part of time we can at least conceptually abstract from the passing of time (in order to, for instance, formulate sentences about this very nun). The nun is the time in change whereas the exaiphnês accounts for the kind of switch, which must occur outside of time. By contrast, an exaiphnês in time would generate precisely the contradiction it is supposed to avoid. Only with a switch out of time (and out of space) can we avoid the contradiction. To the very specific question Parmenides asks, namely when the switch occurs, we can answer: outside of time. By contrast, to account for a continuous and progressive change such as aging, the question would be simply inadequate. We do not ask when the switch occurs because there is no switch. We simply compare different states. I can thus observe (and state) that I am now older than I was before. Between what was before and what will be, there will always be a nun I can conceptually abstract in which it will hold true that I am now older than I was before.