Kurt Riezler’s considerations of ontology and of possibility are closely bound together. He conceives of Being as the urge to realize particular form from out of the range of possible forms: “Being is intrinsically mobile”. It is this dynamic urge that is fundamental to all movement, especially the movement of creative insight.¹ For this is insight which is creative just to the extent that it aligns itself, knowingly or not, with the prior urge of Being itself. Both are essentially unmotivated by anything prior to them.²

The selections below are from Riezler’s 1940 Physics and Reality  In them Riezler speaks in the name of Aristotle to modern physicists.³ The selections are given here in the order in which they appear in Riezler’s text.

Being is intrinsically mobile, changing. What does that mean?

Before we attempt an answer [to the question of Being and its mobility], we shall have to agree upon the meaning of the [word] ‘is’.⁴ Perhaps here at the very beginning lies the source of our dissension. Your meaning of this ‘is’ may not be mine, mine not yours. If I am not mistaken you recognize only one possible meaning of that ‘is’.

I see, however, discontent and resistance in your faces. I can guess what annoys you — that dangerous word ‘is’. You fear to get entangled with its secret. You have worked out a thesis intended to elude it. You do not want to (…) hear that this ‘is’ is doubtful.

You admit perceptions only if they can be confirmed by any possible perceiver. [But] you eliminate the particular individuality of the perceiving subject. You have taken great pains to cast out the individual. You assume one ever present anonymous observer [as] the [only] possible observer. Statements relative to him are for you ‘objective’ statements about reality. By such statements you establish your order of nature. You have, as a consequence of this assumption⁵, no right to pretend that you coordinate a totality of all possible or real perceptions with your model of nature [or] that your design of this model is confirmed by the totality of your perceptions. You have made a selection [from the range of possible perceptions and perceivers] and a very narrow one at that.

You have not eliminated the subject; you have eliminated merely the individual differences [of subjects] in favor of an [undifferentiated] anonymous subject (…) an odd creature, a robot without blood and heart, whose only being consists in reading numbers from the pointers of your instruments.  Your ‘objective’ reality is merely an (…) order relative to this robot observer. All that is not measurement is closed to him. Your most intimate and impressive experiences mean nothing to him. He has no part in the colorful fullness of Being.

So your objective world has become a strange world relative to a strange observer.

Everything [in your view] is unequivocally determined — [your] Real is the only Possible [one] and the [only] Necessary [one]. There is [for you] only one modality of Being.

Where is your criterion (…) that permits one world line and forbids another (…)? You have no such criteria.

Let us look at the relation between [your] kind of causality and the principium rationis. This causality [of yours] presupposes an axiomatic order that underlies the successions [you posit] in time and is built in a very particular way. From this (…) follows the causal relation [you investigate] between events or states. Thus [your] law of causality presupposes a specific axiomatic system. [But we] may deny⁶ this specific order and yet maintain the principium rationis. If there are other axiomatic systems able to cover the order of physical happenings the law of causality [you posit] would have to give way to another kind of determination. The principium rationis would not be shattered. 

In every moment the possibility of motion, even if not actualized, is present, inherent in your reality, as something lacking.⁷

Between moving and being moved, between the possibility and actuality of either, life is suspended. The absent mode is silently present as danger or as need. In the interplay of all these modes of motion you have your life — in their concordance, tension, disunity. All these emotions are knotted together. By their being so knotted they and you are concrete.

Instead of [merely] consulting your [set] scheme of nature [objectively] (…) question your own reality in your actions: your own selves as possibility are the ‘Whence’ [of] yourselves as actuality, the ‘Whither’ of your actions.⁸  The Whence and the Whither are different modalities of Being. The two modes are interconnected in a unity that is not to be divided. In between the two you are at every moment of your life. You are both. You are what you  are able to be.⁹ Your potentialities, even if not actualized now or ever, are nonetheless part of you. From your potentiality you reach out toward your actuality; from your actuality you are bent back to your potentiality. That is the to and fro motion and tension ever present, at every moment. When we pose the one without the other we disrupt the living reality. 

Your actuality at any given time is real in its relation to your potential actions¹⁰, all your possibilities being mutely present. But this potential Being is diversely articulated: [its range includes all] the possibilities of your own selves (…) and [all] the possibilities of the external world constituting¹¹ your environment. One might say: internal and external  possibility. They too are interrelated. They move between harmony and discord. (…)  We have to consider the logos that conjoins them. You cannot comprehend one of its members by tearing it from the others. The detached part would cease to be. The parts exist only as a whole articulated within itself, only together. Each is silently present in the others.

Being is nothing without a world in which it is actualized,  vain is a world that does not reveal Being.

We can say that living beings are always ‘on the way’ from a Whence to a Whither — and that not because Time goes on. Forget Time for a while. In acting and being acted on this ‘being on the way’ has a different meaning. In pure acting the self-constituent being is ‘on the way’ from itself to itself, from its innermost potentiality to the actualization of this potentiality (…) In pure acting the Whence of Motion is somewhat like your inner nature, the Whither somewhat like its fulfilment. In my terminology the Whence is dynamis, the Whither the energeia of this dynamis. This motion is self-movement. It is the joy of all your joy. 

Measured and judged by that self~movement, undergoing action means to be moved. But we are finite beings. Pure acting is not our lot. In undergoing action we move not from ourselves to ourselves, but from one something to another something, neither of which is entirely ‘we’. We are acted on in so far as we are moved aside from the way we are on; in our acting, we are [at once] deprived of our possibilities [and] our actualities are stunted and shattered. Thus I say: in acting and being acted on the Whence and the Whither are not the same Whence and Whither. In acting they are yours, in being acted on they are not. But keep in mind that both acting and being acted on are only modes of one and the same Being, that we are always on both [these] ways. We are able to act only because we are beings who are acted on. And we are acted on only as beings able to act.

All (…) your actions imply undergoing action. Suffering may even be the larger part of your acting.

When our acting is pure acting, which it never is, we move from a potential self to an actual self. This is one of the two modes of our ‘being on the way’. We are all at every moment ‘in between’ our potentiality and our actuality. Do not, please, think of these two termini of our acting as cause and effect, or apply Time to them. (…) Put your mind on the  logical structure linking the two terms together in yourselves so that each is the one of the other. If the first term, the Whence, appears to be prior to the Whither, it is certainly not prior in Time, as is cause to effect. Its priority, if there is priority, is by nature not by time. 

In this reading the two terms [potentiality and actuality, dynamis and energeia] would be related as ‘reason’ to ‘consequence’. (…) This ‘reason’ is, as it were, the soil, the
ground, out of which the action grows. It is ratio essendi.  Disregard your ratio cognoscendi.

From Sappho come forth sweet sounds. Only in singing is Sappho what she is; her own actuality. Sappho silent, the potential singer, is not yet quite what she is: the fullness of her Being. Or better still, consider her language. This language, as [the] pure potentiality of singing, certainly is and [yet] is not [yet] something real. Only in singing does it become wholly itself, its very own reality become sure of itself and enjoying being real. Potentiality thirsts for actuality [= “Being is intrinsically mobile”]. Language wants to be spoken, to sound, Sappho wants to sing.

Sappho’s singing will make clearer what I mean when I speak of pure action: the actualizing of Sappho’s inner nature, passing from potentiality to actuality. In her singing Sappho moves herself, from herself to herself. In this kind of motion singing, not the song, is the Whither, the end.

Consider the kind of Being you must attribute to your language, when you are not actually speaking it. It exists in that mode of Being I call possibility. The essence of language is that it can be spoken. But language is not a mere sum of possible utterances, of vocabulary, and grammar. It is all [an] organized whole, a system, embracing an immensity of possible phrases, styles, all manner of good and bad speaking. This mode of Being, I confess, is not altogether easy to grasp. In its innermost life language seems to be animated and governed by something you call its spirit, a thing to be neither denied nor understood clearly. As beings capable of speech you can conceive of yourselves as being ‘in’ your language as in a field of possibilities. You yourselves are this field. Its inner life, its hidden spirit is part of you. When you speak you pass from possibility to actuality. You actualize the language and yourselves. 

The basis of what you call your inner nature, your Whence, is such a field of possibilities. A field of possibilities is a kind of axiomatic system, like one of your spaces, the three dimensional space of Euclid, for instance. The axioms govern the figures that can be actualized in such a space. In the same way the immanent axioms — which, taken together, are what [one may]¹² call the spirit of your language — rule your speech. Of course you do not know these axioms of your inner nature; they remain secluded. They limit your possibilities; they also guide your actualizing. You may again note for later, that a moment ago I used the term ‘space’, [but this is] not yet your space of the order of the Many…

This field of possibilities has nothing to do with your electrodynamic and gravitational fields. We are dealing with something far more fundamental. In your view of reality there is no such thing as a field of possibilities or even possibility at all. You deal with actualities after having deprived reality of its reach into the realm of the possible. But the possible too is real in its way.

When you regard your inner nature you will recognize that something like a field of possibilities is part of your reality and that this field is endowed with a dynamic force. You yourselves as [related to] such a field are a ‘dynamic agens‘. There is something urging you from possibility into actuality. This very urge is the lifeblood of your existence.

Before leaving [discussion of] the Whence I should mention that it has to do with what I called matter. Matter is potentiality. It is not your matter.

Applying the concept or the Whence as a field of possibilities to our being among others in a common world we may say that your inner nature as a field of possibilities governed by an unseen system of laws or norms or axioms or codes, and endowed with that dynamic urge for actuality, is merely a field in a field or [a] space in space. (…) Your individual field of possibilities stands in a more general space, common to you and to others. You may think of this general space too as governed by laws, ordered by axioms valid for you as well as for others. There may even be, as in your geometry, a hierarchy of spaces of increasing generality leading to the odd conception of the still undetermined space of unlimited possibility, which awaits fashioning: a receptacle of axioms. That I call ultimate matter, but I do not mean your matter. It is this space Plato speaks of in the Timaeus…

In this general space, which is neither your space nor your matter, you and the others-to-you are begotten. The  different individual fields are not side by side, unconnected.  They are in a more general field. It is in this field that you actualize yourselves as individual fields, and so do the others. Thus your moving changes the fields of the others [and] their moving changes yours. Referring to your possibilities you must distinguish between an inner and an outer possibility, the first expressing your inner nature, the other representing the situation that permits you to do A and restrains you from doing B.

Pure possibility is an abstraction. Possibility is nothing in itself. It is what it is through its relation to actuality. Your possibility is a momentum of your reality.

Your present individual actuality (…) may be [conceived as] your possibility actualized at the moment. It is by no means all your possibilities or the best. It is never quite your own. In this present actuality you ‘are’ all you are [currently] capable of, [but at the same time] you ‘are’ somehow [also] your not yet actualized possibilities. At any moment you may be said to be acting in so far as you move from yourselves to yourselves, actualizing and continuing to actualize your innermost possibility [from the range of possibilities]. Acting you enjoy your own selves — and the world.

Your potential being holds more than one actuality. Choosing means a movement from more than one to one.

To you [modern physicists] possibilities are not real. An observer who happened to be of your cast of mind would insist that the actuality expanded in actual space-time is the whole of reality. He would try desperately to connect the actualities located at different points of this space-time by means of your straight-line causality.

[We] move from the possible to the actual within the range of [our] possibilities, actualizing one of them, be it germane or more remote. In their action these two modes of being on the way [from the the possible to the actual and between actualities] are intermeshed.

The movement from actuality to actuality includes another movement from the potential to the actual. (…) This beginning [in the potential] and this end [in the actual], the Whence and the Whither of acting, are not separated by a stretch of time. They must be thought of as synchronous.

Your world is the plane of actuality. Your laws relate  actualities to one another. They are verified by experience in a stratum detached by the anonymous observer from the totality of phenomena. (…) But the plane of actuality is not the entire body of reality. Reality embraces both actuality and potentiality; the surface and the depth, in which the [identities we experience] are engendered [and] from which they strive to emerge. These [identities], called substances, relate [potentiality to actuality and] actuality to potentiality.  At every moment they are in between the concord and discord [of potentiality and actuality]. They move and are moved, act and are acted on.

There is only one foundation. Possibilities progress to  actuality. This is the primary movement.

The past is the actualized part of possibilities, the future the part waiting to be actualized. The past ever increases, the future decreases. It is beyond your power to change the past, an absolute impotence; you may be able¹³ to change the future, a relative weakness [but also a relative potency].

A certain movement is concealed that connects not only present with past and future actualities but also your potentiality with your actuality. In remembering you do not merely go back to past actualities. You remember what you were from the beginning, your potentiality, your inner nature with its secret rules and tendencies. The learning child remembers what he never knew. That is Plato’s Anamnesis. [When] you go back to the ‘Whence’ of your acting in every moment you are fully alive; when not, you lose yourselves.

You will never be able to comprehend the concrete interplay of past and future by merely connecting past and future as parts of your straight-line time of actualities. You must draw in possibility. Then you transcend your concept of time as a line of now points, to each of which belongs a given actuality.

Differentiate actual fields and fields of possibility, which are [fundamentally to be distinguished but are] related to each other. Perhaps that would help physics too and make it easier for you to deal with matter.

When you take hold of Matter — a bit of Matter here and now — it becomes to you nothing but a physical field of force. Thinking about the physical field of force and its changes you feel you need something that produces and agitates such a field: Matter reappears as a ‘dynamic agent’. So you endow Matter with a kind of double nature. In that you are right. But note: this double nature is not contradictory, nor is it something to get free from. The doubleness is unity, articulated within itself. The field of force is the present actuality of a field of possibilities which strive to actualize themselves. That is ‘matter’.