Metaphysics, Philosophy

Between Possibility and Reality: Heisenberg’s Appeal to Aristotelian Metaphysics, Part One

by Dave Seng

“As there is a material object behind every sensation, so there is a metaphysical reality behind everything that human experience shows to be real.” – Max Planck, Scientific Autobiography

[Note: I would like to thank Dr. Derek Gardner for reading a draft of this essay and supplying helpful suggestions. His scholarship saved me from making errors when describing quantum mechanics and I deeply appreciate his insight.]

I recently heard a professional philosopher say that metaphysics is no longer a dirty word in the field of philosophy. This was good news to me, because for the last four hundred years or so metaphysics has been considered a lost cause in philosophy. Upon reflection, however, I think there has been a small resurgence in the interest of classical metaphysics but the philosophy of mind, language, science, politics, and ethics still seem to be the most popular areas of study in the field. I’m still told that professional positions for metaphysicians are hard to find. Nonetheless, it is fascinating that philosophy is rediscovering its primary role—to explicate the most universal principles of reality and discover the rules, axioms, and laws that make our universe, fields of learning, and human experience possible in the first place. I think the ultimate questions of reality and what it means to be human will never really go away. Thoughtful individuals will always try to offer systematic attempts to illumine our human experience in depth and set it in a vision of the whole of reality. Why might there be an emerging interest in metaphysics and what would that tell us about the relationship between philosophy and science?

Aristotle explains in his Metaphysics that there is a science (for Aristotle ‘science’ is a body of knowledge) which is concerned with “being as being” and that the primary causes and principles of being are the object of study for the metaphysician. This is the formal study of ontology, the metaphysical exploration of all existing things as they exist, the properties of being, and whether certain things, whose existence can be questioned, do or do not exist. Aristotle also laid out the tactical possibilities for conducting what we now call the physical sciences – the study of the structure and behavior of the natural world through repeated observation and experiment. For Aristotle, however, and the many classical and medieval philosophers that came after him, the physical world and the ultimate principles of reality (what they would have called ‘physic’ and ‘metaphysic’) are not to be divorced or separated because both are needed to explain the ultimate nature and significance of reality. While the subdivision and classification of learning and science is helpful for sharpening one’s focus on their object of study, most areas of study ultimately fall back on basic first principles that attempt to explain or support their overall project, such as the principle of sufficient reason, the law of identity, the law of noncontradiction, correspondence, cause and effect, act and potency among others. Perhaps one reason metaphysics is being re-discovered is that all fields of inquiry, whether the social sciences or physical sciences, use foundational first principles which reflect their basic assumptions about the nature of the universe and how the world works. Note that nearly all our basic assumptions are not empirical in the sense used by Enlightenment philosophers and natural scientists and yet it would be foolish to discard them. There are many immaterial and material aspects of reality. The union of the immaterial with the material has often been discarded or forgotten in Western thought but recently have been rediscovered with interesting metaphysical corollaries. Every cosmology, mathematical formula, scientific hypothesis, and ethical theory has metaphysical implications.

Another reason I think metaphysics is being rediscovered is that a few physicists and mathematicians in the twentieth-century ventured into the discussion and pointed out that physics and metaphysics are indeed related and ought not to be detached. This was a profound change in Western thought at least since the Enlightenment. Due to the skeptical theories of Descartes, Hume, Hobbes, and Kant, metaphysics was considered dead or impossible to pursue. However, interesting scientific developments in the early part of the twentieth-century changed things. Einstein’s colleagues, Max Planck, Werner Heisenberg, G.H. Hardy, Niels Bohr, and Erwin Schrödinger, among others, argued for a new understanding of nature due to the quantum discoveries of their day that described the behavior of reality at the atomic scale, where standard Newtonian physics failed to do so. Here, a basic tenet of quantum mechanics, as opposed to classical mechanics, is that reality, at an atomic level is not causally linear or smooth in its behavior but probabilistically discontinuous and discrete. In Newtonian physics, for instance, and in the classical “every day” large-scale sense to which it applies, it is generally possible to determine the future states of a system by knowing its present state (e.g., we can predict where a baseball will land given some initial conditions). In the new atomic physics of the twentieth century, this was no longer the case. Classical mechanics has at its basis the contention that all states of a considered system can be measured and known. When we describe atomic physics with quantum mechanics, on the contrary, one must accept that it is impossible to know the exact value of a parameter without measuring it, and one can know it only for that measurement. Heisenberg’s discovery of quantum indeterminism suggests that in the moment of an atomic measurement, the system (e.g., a molecule) is necessarily disturbed (e.g., by a probing photon) thus “collapsing” the original potential possibility-space into one state of the many probable states, some with much higher probability, but otherwise without any reason to “collapse” into one or another particular possible state (Silva, 637). The most one can do to describe the state of any given system, before or after the measurement, is to provide a probability for the outcome of that measurement (Dirac, 73).

From the standpoint of Aristotelian philosophy, Werner Heisenberg is especially interesting due to his specific appeal to Aristotelian categories of act and potency when describing his theory of indeterminism. Before getting further into Heisenberg’s interpretation of quantum mechanics, however, it is important to understand the central Aristotelian categories of Act and Potential.

As a quick review, ‘act’ or ‘actuality’ simply refers to that which exists. It is the physical, concrete existence of something (philosophers call this the ‘positive mode of perfection’ but we will not go into that here). For now, think of act or actuality as that which really exists here and now—a physical object. Another way to think of act is that which is ‘informed matter’. (In classical philosophy, matter is not form and form is not matter. Form is the essence of a thing or that which makes something the kind of thing it is and without which it can not be. Ordinarily, essence is considered distinct from existence. This is one reason why all reality has an immaterial as well as material elements.) ‘Potential’ or ‘potency’ is simply all the capacities for change, transformation, or movement that which is in act has. For example, a student has the capacity to become a great mathematician if she uses her rational capacities well. A rubber ball has the capacity or ability to be melted down and formed into a figurine, balloon, or tire. Potential is another way of describing all the possible modes of being something has (it is always innate to that which is in act). Potency is never unlimited, however, and is governed by the essence, nature, or form a thing has—and this will be important when we get to Heisenberg’s understanding of probability and atomic potency. For example, a hamster will never become a helicopter pilot, and a cephalopod will never become an architect because potency only relates to the nature (or essence) of the thing itself. Act and potency are metaphysical co-principles that help us make sense of the world around us. The act/potency distinction is an absolute feature of reality and is accepted by all serious philosophers from the classical tradition through the early modern period, including neo-Platonists and Aristotelians. For example, the neo-Platonist philosopher, Plotinus, appropriated Aristotle’s categories of act and potency when describing change.

Part two will specifically focus on Werner Heisenberg’s book, Physics and Philosophy with some concluding remarks from Max Planck.

Works Cited:

Dirac, Paul. The Principles of Quantum Mechanics. Oxford, Clarendon Press, 1958.

Silva, Ignacio. “Werner Heisenberg and Thomas Aquinas on Natural Indeterminism.” New Blackfriars, 2013, 635 – 653.

Metaphysics, Philosophy

A Very Short Introduction To Aristotelian-Thomist Metaphysics: Act and Potency, Part. 2

by Dave Seng

Although Aquinas applies the concepts of act and potency to almost every facet of existence, from natural science to the features of the intellect, and even to the characteristics of the soul and angels, the best starting point to understand the important categories of act and potency is the relationship these ideas have with Being. A large part of Aquinas’s philosophical methodology is to distinguish and apply the categories of act and potency to all of reality. (Sometimes Aquinas uses the word “powers” to mean innate potencies or abilities.) Aquinas himself tells us that all reality, or Being, can be divided between act and potency. “Potency and act divide being and every kind of being” (400). At another point Aquinas explains, “Since Being properly signifies that something is, in act, and act is properly ordered to potentiality, a thing is, in consequence, called Being absolutely according as it is primarily distinguished from that which is only in potency; and this is each thing’s substantial Being” (23). Furthermore, Aquinas expands upon the nature of Being, “Being is the actuality of every form or nature; for goodness or humanity are spoken of as actual only because they are spoken of as being. Therefore, being must be compared to essence, if the latter is distinct from the former, as act to potency” (17). Something is “in act” or in the state of actuality when it is existing in physical reality or knowable through the intellect. Echoing Aristotle, Aquinas tells us “everything is knowable only in so far as it is in act” (24). The concept of Being which is the most general concept we have of reality, can nevertheless be delineated between act and potency.

Being, however, has two senses — one sense refers to physical objects of reality and, in the second, intellectual objects of the mind such as statements, ideas or concepts such as goodness or humanity, and mathematics. Again Aquinas explains, “’To be’ can mean either of two things. It may mean the act of being, or it may mean the composition of a proposition effected by the mind in joining a predicate to a subject” (17). In sum, all of reality exists in one way or another in act — either in acts of perception or acts of the intellect. It is important to keep in mind, also, that Aquinas does not hold to a separate realm of ideas as Plato does, or the idea that the mind itself determines reality. As will be explained later, Aquinas holds that form and matter are always united together. In his epistemology, however, Aquinas holds that the natural physical things of this world (things existing “in act”) have their own intractable reality and they are known by way of the five senses. It is through abstraction that one realizes essences and universals that exist in the intellect. For example, “redness” is realized by viewing several red objects. Aquinas, following Aristotle, is grounded in nature and believes that the physical objects of this world have their own inherent and intrinsic characteristics and that these characteristics can be known through abstraction. In other words, reality is the determinate of order. According to Aquinas, “Our intellect cannot know the singular in material things directly and primarily. The reason of this is that the principle of singularity in material things is individual matter, while our intellect… understands by abstracting the intelligible species from such matter. Now what is abstracted from universal matter is the universal” (461). Aquinas indicates that it is possible for the intellect to know the particular through reflecting on the universal. All Being, nonetheless, exists in the universals and particulars that make up the being and becoming of this world.

For Aquinas, Being includes act and potency, but how does change actually take place in the realm of becoming? More specifically, what is the cause of change? With the exception of universals, virtually all things of the physical world are subject to change or movement. As noted earlier, both living and non-living things experience change. Change is the actualization of a thing’s potential. Aquinas provides this definition of change, “A thing requires to be moved by something in so far as it is in potency to several things; for that which is in potency must be reduced to act by something actual, and to do this is to move” (658). Change, then, is potency reduced to act. However, an outside and additional element is necessary to bring about change. Potency is needed for change, but it is only a necessary condition, not a sufficient condition to bring about change. Aquinas explains, “Now it is impossible for a thing’s being to be caused by its essential principles, for nothing can be the sufficient cause of its own being, if its being is caused” (17). In other words, for an acorn to change into a beautiful oak tree, more than potential is needed. In order for an oak tree to develop from an acorn, the acorn must be nurtured by sunshine, rain, nutrients in the soil, and time. Something else, always itself in “act,” is needed to actualize a potential. “For whatever is in potency can be reduced to act only by some being in act” (14). Potency itself cannot bring about act — just as non-being cannot bring about being.

That which reduces a potential to act is called a cause and a quick overview of Aristotle’s famous four causes is, therefore, necessary. Aquinas is fully committed to the Aristotelian four causes. The first cause is the material cause — that out of which something is actualized. The second cause is the efficient cause — that by which something is actualized. The third cause is the formal cause — that into which something is actualized. The fourth cause is the final cause — that for the sake of which something is actualized. A biological example will help explain how these four causes work in the physical world. To understand the basics of the human heart, it is important to know what it is made of — its material cause. In this case, the material cause of a heart is muscle. The efficient cause rests in the DNA that structures and orders cells in such a way as to create a muscular heart and not a kidney or spleen. The formal cause is that which the heart muscle is fashioned into — ventricles, arteries, aorta, etc. The final cause serves the purpose of pumping blood. For both Aristotle and Aquinas, final causes are significant and found whenever cause and effect relationships are seen. The totality of the three previous causes all serve a goal or ultimate end, culminating in the final cause. Focusing on act and potency, the efficient cause is that which actualizes a potency. That is why Aquinas says, “Now everything which is in any way changed is in some way in potency” (38). In other words, there is always an external component to a change which reduces potency to act, and that external component is the efficient cause. The builder of a ship is the efficient cause of the ship, and the DNA in the acorn is the efficient cause of the oak tree.

All things in act, therefore, are the subject or cause of change. That which is in act is always a composition of act and potency. According to Aquinas, all things are made up of a composition. “Thus, in everything which is moved, there is some kind of composition” (39). One of the metaphysical aspects of reality is that the normal everyday things of this world are composed of act and potency. For Aquinas, another significant aspect of all of reality is the composition of form and matter. Aquinas explains, “matter is that which is in potency” (15). And this relates to change as well, according to Aquinas, “For just as matter, as such, is in potency, an agent, as such, is in act” (21). The twofold composition of form and matter is simply a restatement of the Aristotelian understanding of formal and material cause. It is also important to understand that things which change according to a final cause must also be composed of form and matter. Without form there would not be an essence to something and an inherent or final nature could not be realized. Aquinas explains how this final end is related to act and form, “upon the form follows an inclination to the end… for everything, in so far as it is in act, acts and tends towards that which is in accordance with its form” (27). For Aquinas then, the immaterial aspects of causation are always connected to act and potency, and form and matter.

In addition, that which is in act is combined with form and matter, “being is the actuality of every form or nature” (17). Just as everything is composed of act and potency, all things are composed of form and matter. “Hence, being itself is the actuality of all things, even of forms themselves” (21). As we have seen already, being is that which is in act. We can therefore understand, that which is in act is also combined of form and matter. Aquinas explains that universals and essences can be infinite, but form is bound and contracted to matter, “Just as immaterial things are in a way infinite as compared to material things, since a form is, after a fashion, contracted and bounded by matter, so that form which is independent of matter is, in a way, infinite” (620). In other words, apart from universals, essences, or abstractions, forms are always in combination with matter and that which informs, or participates in the transformation of matter when it changes, and matter is that which participates in the potential of receiving the form. “Forms which can be received in matter are individualized by matter” (16). Echoing Aristotle, Aquinas holds that in physical objects, forms are inherent or immanent in the things themselves.

As it turns out, the concept of potency is powerful and helps to provide a foundation for understanding the metaphysical structure of things that undergo change in this world. Therefore, wider implications of the act/potency distinction warrants exploration. From physical nature to human beings, everything that is in act is also in potency. Potency, therefore, precedes and supersedes actuality and provides continuity when things change because that which is in act will change according to its nature, or essence, through potency. Potency is not something that can be measured by the tools of the physicist, but its effects can be. Science, after all, is not interested in matter in and of itself, but rather in the properties, capacities, and possibilities that the matter contains by virtue of its potency. Whenever a drug manufacturer gives a list of possible side effects (such as bleeding, restlessness, bloating, blindness, etc.) it is explaining the potentialities that might occur if certain conditions are met. In information science, we know that computers only perform as they do because electrons have certain properties and not others. Finally, we do not yet know the capacity and limitations of the human mind and intellect. The capacity for the mind to grow, develop, and learn speaks to the potential of what it means to be human. Human beings are amazing and have the ability to adapt, appropriate knowledge, and develop greater and greater abstraction. Pure potentiality can never be measured empirically, but to deny its reality would be intuitively and conceptually absurd. Aquinas’ act/potency and his correlative form/matter distinctions make the most sense out of reality and provide a significant foundation for understanding the metaphysical structure of change and the world we live in.

Works Cited

Aquinas, Thomas. The Summa Theologica, Volume 1. Great Books of the Western World. Vol. 17. Encyclopedia Britannica, Inc., 1999