Schopenhauer called his magnum opus The World as Will and Representation (Die Welt als Wille und Vorstellung). In this blog, I will try to elaborate on the meaning of the term 'Will' (Wille) and its application to and relevance in modern science, especially quantum physics.

The concept of will has a long history in philosophy. Starting with the ancient Greek philosophers, who did not yet have an elaborate idea of will as it later developed in Scholastic and modern philosophy, the term βούλησις can mean 'willing' in general, but also 'wish', 'desire' or 'purpose'. The Stoics used this word for the reasonable desire that a wise man is allowed to feel. Cicero later translated this word to 'voluntas' in Latin:

Id cum constanter prudenterque fit, eius modi adpetitionem Stoici βούλησις appellant, nos appellemus voluntatem.
[Cicero, Tusculan Disputations, IV, vi]

(Now here this strong desire is constant and prudent, it is called by the Stoics βούλησις – we may call it will.)

And further:

…voluntas est, quae quid cum ratione desiderat.

(Will is that which desires something with reason.)

Plato divided the soul into three parts: logos or reason (λογιστικόν), thymos or spirit (θυμοειδές) and eros or desire (ἐπιθυμητικόν). The latter is that part of the soul which is the seat of the desires, appetites and affections (see Plato's Republic, 475b).

The Stoic's concept of βούλησις is likely based on the definition Aristotle provided in De Anima, as a "form of appetite, when appetite moves according to reason":

ἡ γὰρ βούλησις ὄρεξις ὅταν δὲ κατὰ λογισμὸν κινῆται, καὶ κατὰ βούλησιν κινεῖται.
[De Anima, 433a 23]

(For will is a form of appetite/desire, when appetite/desire moves according to reason and is moved according to will.)

While for Aristotle and the Stoics, βούλησις is an activity of reason and not a distinct part of the mind, Augustine and the later Scholastics, defined 'voluntas' as a separate faculty:

Communis igitur opinion est quod, cum in parte intellective sive ratoinali duae ponantur potentiae quarum une est cognoscens et dicitur intellectus, altera non cognoscens sed appetens quae dicitur voluntas…
[Pietro Pomponazzi, De Fato]

(The common opinion is that there are two faculties in the intellective or rational part [of the mind], of which one is cognitive and is called 'intellect' and the other is not cognitive but appetitive, which is called 'will'.)

The Epicurean Lucretius considered will or wish as a form of movement (motus) that begins ex animi voluntate (from the will of the soul) and initiates the actions of the body in order to seek pleasure. He even thought that atoms must contain some “innate power” of motion.

Jumping ahead now to the Romantic philosophers, 'will' obtains a much broader and encompassing meaning than when considered as an active faculty of the mind employed to make decisions, strive towards an end or act morally in everyday life. For example, Novalis believed will to be the basis of all creation:

Im Willen ist der Grund der Schöpfung.
[Das Allgemeine Brouillon, notebook 512].
Wir stossen immer zuletzt an den Willen – die willkürliche Bestimmung – als wenn dies überall der eigentliche und notwendige Anfang wäre.
[Das Allgemeine Brouillon, notebook 568]

(In the end, we always arrive at the will – the voluntary determination – as if this were everywhere the proper and necessary origin/beginning.)

Schelling defined will as primary being:

Es gibt in der letzten und höchsten Instanz gar kein andres Sein als Wollen. Wollen is Ursein, und auf dieses allein passen alle Prädikate desselben: Grundlosigkiet, Ewigkeit, Unabhängigkeit von der Zeit, Selbstbejahung. Die ganze Philosophie strebt nur dahin, diesen höchsten Ausdruck zu finden.
[Über das Wesen der menschlichen Freiheit, VII 350]

(In the ultimate and highest instance, there is no other being than willing. Willing is primary being, and to this alone are all its predicates applied: groundlessness, eternity, independence of time, self-affirmation. The whole philosophy strives to find this highest expression.)

The Romantic concept of the will shows already clear signs of the panpsychist meaning it will adopt in Schopenhauer's philosophy.

On a more scientific level, the theory of dynamism developed by Leibniz and Boscovich in the 18th century proposed that all phenomena of nature are manifestations of force. Schopenhauer also adopted this concept when he said that the will manifests itself as the forces of nature.

Eduard von Hartmann, who was a follower of Schopenhauer, believed that ideas define the 'what' of the world and the will its 'that'. The opposition of the will and the order of the ideas causes the emergence of consciousness and the individuals.

We now examine more closely Schopenhauer's concept of will. It's a more radical concept since it deviates from the traditional conception of will as an active faculty of the human mind and also what differentiates us from animals and inanimate things. Philosophy prior to Schopenhauer considered the intellect as the primary faculty of the mind and even went as far as to determine the ultimate reality as rational or mind (see German idealism, esp. Hegel). Schopenhauer turns this around and makes will the primary reality and intellect only a secondary faculty that is a manifestation of the will in human beings and animals.

Der Wille, als das Ding an sich, macht das innere, wahre und unzerstörbare Wesen des Menschen aus: an sich selbst ist er jedoch bewusstlos. Denn das Bewusstsein ist bedingt durch den Intellekt, und dieser ist ein blosses Accidenz unsers Wesens: denn er ist eine Funktion des Gehirns.
[Die Welt als Wille und Vorstellung, volume 2, chapter 19)

(The will, as the thing-in-itself, constitutes the inner, true, and indestructible nature of man; yet in itself it is without consciousness. For consciousness is conditioned by the intellect, and the intellect is a mere accident of our being, for it is a function of the brain.)

Das Ding an sich hingegen ist allein der Wille. Demach ist er der Schöpfer und Träger aller Eigenschaften der Erscheinung.
[Parerga und Paralipomena, volume 2.33]

(But the thing-in-itself alone is the will. Therefore the will is the creator and bearer of all the properties of the phenomenon.)

Schopenhauer identifies the Kantian thing-itself as the Will, as the ultimate reality of the world:

Der Wille als Ding an sich ist von seiner Erscheinung gänzlich verschieden und völlig frei von allen Formen derselben, in welche er eben erst eingeht, indem er erscheint, die daher nur seine Objektivität betreffen, ihmselbst fremd sind.
[Welt als Wille und Vorstellung, I.23]

(The will as ting-in-itself is quite different from its phenomenon, and is entirely free from all the forms of the phenomenon into which it first passes when it appears, and which therefore concern only its objectivity, and are foreign to the will itself.)

Demzufolge ist die Materie Dasjenige, wodurch der Wille, der das innere Wesen der Dinge ausmacht, in die Wahrnehmbarkeit tritt, anschaulich, sichtbar wird. In diesem Sinne ist also die Materie die blosse Sichtbarkeit des Willens, oder das Band der Welt als Wille mit der Welt als Vorstellung.... Daher ist jedes Objekt als Ding an sich Wille, und als Erscheinung Materie.
[ibid, II.24]

(Consequently, matter is that whereby the will, which constitutes the inner essence of things, enters into perceptibility, becomes perceptible or visible. Therefore in this sense matter is the mere visibility of the will, or the bond between the world as will and the world as representation... Therefore, every object as ting-in-itself is will, and as phenomenon is matter.)

'Will' is the somewhat ambiguous term Schopenhauer gives to this concept of a dynamic reality which we cannot know directly but only through the sense data (appearances, representations) given to us in our mind or immediately through the individual will in self-consciousness.

The common idea of will throughout history seems to be that it is a drive or force that we find in us but also in nature, a force that strives to accomplish or arrive at something. This force is what moves the world, the cause of all change in nature. Schopenhauer imagined this force to be pervasive throughout nature, because everything is an objectivation or appearance of the one ultimate reality, i.e. 'will'.

If we think of it as a pyramid with will at the bottom, as the ultimate reality of everything, the upper levels are different grades of objectifications of the will. First, the fundamental forces of nature, like electro-magnetism, gravity are the immediate objectifications of the will.

Aber die Materie selbst ist bloss die Wahrnehmbarkeit der Erscheinungen des Willens. Daher hat man in jedem Streben, welches aus der Natur eines materiellen Wesens hervorgeht und eigentlich diese Natur ausmacht, oder durch diese Natur sich erscheinend manifestiert, ein Wollen zu erkennen, und es giebt demnach keine Materie ohne Willensäusserung.
[Über den Willen in der Natur, p. 84]

(But matter itself is only the perceptibility of the appearances of the will. Therefore, one must recognize in every striving, which proceeds from the nature of a material being and actually determines its nature, a willing, and consequently, there is no matter without the expression of the will.)

Matter, according to Schopenhauer, is efficient causality, and where there is causality, there is will and no will acts without causality. The essence of each thing is the specific kind of its operating or acting. Or as the Scholastics already taught: operari sequitur esse, i.e. from the essence of each being follows its activity, or what Schopenhauer called the aseity of the will ("Denn ich will je nachdem ich bin: daher muss ich seyn je nachdem ich will" (For I will according to what I am: therefore, I must be according to what I will)).

In den dumpfen und blinden Urkäften der Natur, aus deren Wechselspiel das Planetensystem hervorgeht, ist schon eben der Wille zum Leben, welcher nachher in den vollendetsten Erscheinungen der Welt auftritt, das innerlich Wirkende und Leitende und bereitet schon dort, mittelst strenger Naturgesetze auf seinen Zweck hinarbeitend, die Grundfeste zum Bau der Welt und ihrer Ordnung vor.
[Parerga und Paralipomena, 2nd edition, II, p. 229 f.]

(In the dim and blind primary forces of nature, from whose interaction the planetary system originates, is already the will to life, that later appears in the most perfect phenomena of the world, what operates and directs intrinsically, and it already anticipates here, by means of stringent laws of nature working towards its goal, the foundations for the construction of the world and its order.)

The will also manifests itself in the inorganic realm as mechanistic and chemical forces, as repulsion and attraction, as energy, or, for example, in the process of crystallization.

The organic life, which includes plants, animals and human beings, expresses the will as life force, as “will to life”, as motion, reproduction, propagation of the species. Although Schopenhauer passed away before Darwin published his book on evolution, I think that the will as understood by Schopenhauer is clearly manifest in the evolutionary forces of natural selection, mutation and adaptation.

Schopenhauer thought that the life force has three modes of appearance: irritability, sensibility and reproductivity. These concepts originated in 18th century medical science. Irritability is the contraction of the muscle as a reaction to changes in an organism's environment. The will is immediately objectified in irritability. Sensibility is basically sensation or perception and is associated with the nervous system. Its highest manifestation is thinking or intellect which connects sensation with an external cause. And finally, reproductivity manifests itself as growth in plants and the sexual drive within animals and human beings.

In a nutshell, "the organism is just the appearance, visibility, objectivity of the will". So, we can see why Schopenhauer used 'will' as an appropriate term for all forces of nature, from mechanistic to organic forces. Will is then this dynamic concept of force or drive that manifests itself as a blind and purposeless force in nature, but also as a force driven by motives in living beings.

The question remains if 'will' as understood by Schopenhauer is still relevant today with respect to modern science, especially quantum physics. The preliminary answer is a resounding 'yes'.

In quantum physics, the thing-in-itself, or reality, is the quantum field, a “sea of dancing energy”:

The quantum field is seen as the fundamental physical entity; a continuous medium which is present everywhere in space. Particles are merely local condensations of the field; concentrations of energy which come and go, thereby losing their individual character and dissolving into the underlying field.
[Fritjof Capra, The Tao of Physics, 1991, p. 233]

David Bohm called the unbroken and undivided reality holomovement. Like Schopenhauer's will, it is undefinable and immeasurable, it is an implicate order not in time and space, which is unfolded into the explicate order of the world we perceive and experience. In a sense then, there is an unfolding, evolving process from the implicate order to an explicate order, similar to the objectivations of the will.

According to Ervin Laszlo:

The primary reality is the quantum vacuum, the energy- and information-filled plenum that underlies our universe.
[Science and the Akashic Field, 2004, p. 140]

In the last count matter is but a waveform disturbance in the nearly infinite energy-sea that is the fundamental medium-and hence the primary reality - of this universe, and of all universes that ever existed and will ever exist.
[ibid, p. 142]

That the universe is a dynamic holistic energy field is similar to Schopenhauer's idea of the will as a dynamic force that constantly strives to manifest itself in a plurality of phenomena that come and go incessantly.

In fact any area of the Universe, however small, is constantly subject to quantum fluctuations. These produce particles which appear 'out of nowhere,' and vanish back into 'nowhere.' This 'nowhere' is not 'in our Universe' but constantly communicates with it, as a kind of background or underlying ground. At the back of the Universe (as it were) there lies a vast field of energy.
[Graham Dunstan Martin, Does it Matter? The Unsustainable World of the Materialists, 2005, p. 143]

In Nietzschean terms, a quantum of energy (particle) could be considered a quantum of the Will to Power as it seeks to discharge or radiate its force or energy.

Gary Zukov described reality as “fundamentally dancing energy” in his classic The Dancing Wu Li Masters:

If there is any ultimate stuff of the universe, it is pure energy…According to particle physics, the world is fundamentally dancing energy; energy that is everywhere incessantly assuming first this form and then that. What we have been calling matter (particles) constantly is being created, annihilated and created again.
[The Dancing Wu Li Masters, 1980, p. 193]

And also, will could be associated with the concept of 'quantum vacuum', a seething mass of virtual particles produced by quantum fluctuations:

...the zero-point energy of the vacuum appears as a vast omnipresent ocean of infinite energy…
[Michael Talbot, The Holographic Universe, 1992, p, 21]

I could add more quotes from physicists, but there seems to be a general consensus regarding reality as matter-energy, as a dynamic fundamental force underlying everything in our phenomenal world.

I think if Schopenhauer lived today, he would embrace quantum physics and adduce its theory of matter-energy as an example confirming his metaphysical concept of the will.