Aristotle, Aquinas & Emergence

I was asked to write an article relating the teaching of Aquinas to contemporary science for the journal Scientia et Fides. I decided to use and further develop the material contained in my doctoral dissertation. I expanded my reinterpretation of the classical notion of emergence, with its emphasis on the role of downward causation, in terms of the fourfold notion of causation in Aristotle and Aquinas, and the theory of divine action offered by the latter. The PDF version of the article is available HERE.

Abstract of the article:

One of the main challenges of the nonreductionist approach to complex structures and phenomena in philosophy of biology is its defense of the plausibility of the theory of emergence and downward causation. The tension between remaining faithful to the rules of physicalism and physical causal closure, while defending the novelty and distinctiveness of emergents from their basal constituents, makes the argumentation of many proponents of emergentism lacking in coherency and precision. In this article I aim at answering the suggestion of several thinkers to redefine emergence and downward causation in terms of the broader Aristotelian view of causation. In addition, I further develop this interdisciplinary conversation to include theological implications of emergentism, analyzed in reference to Aquinas’ understanding of divine action in terms of the same fourfold division of causes—bringing thus natural science, philosophy, and theology into creative and fruitful dialogue.

Keywords: emergence; downward causation; hylomorphism; teleology; Aristotle; Aquinas.

 

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Metaphysics of Downward Causation

I have just finished writing my presentation for the conference on Agency and Quantum Physics in Innsbruck. I’m excited about it. This is the first time that I’m invited to give an hour long talk at the major session of an international conference. The conference begins on March 30th and ends on April 2nd. Here is the abstract of my paper:

Metaphysics of Downward Causation:
Nonreductionist Physicalism versus New Aristotelianism

Mariusz Tabaczek, O.P.

Graduate Theological Union, Berkeley, CA

Abstract

Many proponents of methodological nonreductionism in contemporary science find the notion of downward causation (DC) a sine qua non of the strong (ontological) version of emergence (EM), which strives to give an account of the irreducible character of the complex levels of the organization of matter. But what for many is the essence of nonreductionist physicalism, carries with it quite a bevy of problematic issues, and becomes a stumbling block and an obstacle for those, who acknowledge the metaphysical and logical inconsistencies of the emergent theory based on the idea of DC. For how can physicalism be non-reductionist? How can DC be reconciled with the causal closure of physics? What do “higher” and “lower” levels refer to? What is causal in DC? What is being caused (acted upon)? What is the very nature of DC?

I will argue that the defense of DC requires from us a broader notion of causation, which goes beyond the efficient causes accepted and described in modern science. I want to argue in favor of the retrieval of formal causation in particular. Its acceptance not only makes EM and DC plausible, but also helps to overcome and replace Humean causation of events with the causation of living and non-living beings, explained in terms of their causal powers and dispositions. I hope to show, in the course of my presentation, that true non-reductionism needs to be philosophically grounded. Yet it can still remain compatible with science provided it values and is open to the reflection offered by philosophy of nature. My position follows new Aristotelianism developed within the analytic tradition, although an explicit reintroduction of formal cause goes beyond it to the original thought of Aristotle.

Philosophy of Causation – Vol. 3 – Modernity

The struggle between more theoretical approach to scientific explanation in medieval Oxford and the empirical and causal approach of Aristotle promoted in Paris, prepared the ground for the big change which came with modernity. The advance of the new science brought a gradual dominance of reductionist empiricism and rejection of causal explanation in metaphysics. The third part of the first segment of my special comprehensive exam depicts the way in which this change happened, in reference to five philosophers from that period.

René Descartes (1596-1650)

51U5u9K+ABL._SY300_In order to understand methodology, ontology, and reflection on causality presented by Descartes, the father of the philosophy of classical science, we must remember that he was deeply rooted in Aristotelianism and scholasticism (deeper than it is usually acknowledged). He was particularly impressed with Aristotle’s demonstrative ideal of knowledge best exemplified in mathematics. His ambition was to apply this methodology to the physical sciences: “In physics I should consider that I knew nothing if I were able to explain only how things might be, without demonstrating that they could not be otherwise. For having reduced physics to mathematics, this is something possible …” (Oeuvres de Descartes). In order to make it happen he introduces a dualist ontology in which material substance is subject to mathematical, mechanical and deterministic description, and is distinguished from mind, which is unextended but capable of thought.

Descartes1However, because he was rooted in Aristotle, Descartes saw scientific knowledge being not only demonstrative, but also explanatory, and therefore referred to causal description (even if he understood explanation only mechanistically). Thus, he would put an emphasis on experimentation and value hypotheses, saying in his Discourse that he finds experiments “more necessary in proportion as our knowledge advances.” He was indeed both a keen observer on nature and careful experimenter. He saw hypothesis as: a) being equivalent with mechanical explanation, or b) offering possible explanations of phenomena, or c) suggesting the “true cause” of phenomena based on experimental evidence. But this aspect of Descartes’ method would never hinder nor question his rationalism. In the end he would regard experiments as merely confirmatory and not capable of refuting conclusions that he arrived at by rational insight. He says that: “while our experiences of things are often fallacious, deduction (…) can never be wrongly performed by an understanding that is in the least degree rational” (Rules for the Guidance of our Native Powers). To sum up, we can say that we find in Descartes a philosopher trying to relate his a priori deductions to the actual world which he experienced and in which he performed his experiments. He would find the latter, practical part of his methodology, providing data for analysis and an opportunity for mind to gain an intuition of clear and distinct ideas underlying the particulars it has experienced.

Descartes on StampConcerning philosophy of causation, while Aristotelian ideal of strict demonstration through causes permeates his work, Descartes rejects Philosopher’s fourfold notion of causality. Replacing the complex scholastic system of substantial forms, qualities of various kinds, elements, and other particles, with the clear and distinct idea that bodies are composed of particles in motion, he banishes formal and final causality (the latter he saw as being beyond human understanding). Though he still subscribes to material causality, he reduces it to basic physical constituents (rejecting “primary matter”), and eventually finds himself left with just one – efficient cause. Because it bears the burden of all other types of causation, Descartes develops a more complex theory of efficient causality. He distinguishes between the efficient cause of being and existence of all created things, which he attributes to God (efficiens and totalic causa), and efficient causes of various phenomena of the physical world (they have more explanatory power from the scientific point of view). His view of causation becomes deterministic. He sees the determinism of natural laws built into the efficacy of mechanical motion. Ends are predetermined by God and are opaque to human understanding, but through the laws that God predetermined “as the efficient cause of all things,” we can explain “the effects that we perceive by senses” (Principles of Philosophy).

Gottfried Wilhelm Leibniz (1646-1716)

Descartes won a great popularity among philosophers of his time. His method, including his causal reductionism, was followed by Hobbes, Gassendi, and Spinoza. However, there is one philosopher who would depart from this Cartesian tradition. Although Leibniz had followed in his early reflection the crowd of philosophers who valued mainly mechanical principles, he eventually changed his mind and become a defender of the plural notion of causality (which he defined in a manner that was peculiarly his own).

Gottfried Wilhelm von LeibnizLeibniz’s early fascination with mechanical philosophy finds its best expression in the paper written in 1677 (On a Method of Arriving at a True Analysis of Bodies and the Causes of Natural Things), in which he states that: “since we may perceive nothing accurately except magnitude, figure, motion, and perception itself, it follows that everything is to be explained through these four.” Here we can see Leibniz who was convinced that through experimentation and observation one can arrive at the mechanical explanation which supplies ultimate “true causes” of phenomena.

About eighteen years later, in Specimen Dynamicum, Leibniz is less optimistic about mechanical character of scientific explanation. Reflecting on the causes of motion, he proposes a new solution through the idea of force. What is crucial here is that he treats force as something prior to extension, present everywhere and implanted by the Author of nature. He distinguishes between active and passive aspects of force, and thus goes back to formal and material causality as defined by scholastics. Active force is of two kinds: a) a primitive active force which is nothing more but the “first entelechy,” and corresponds to the soul or substantial form; and b) a derivative active force which is exercised through limitation of primitive force resulting from conflicts between bodies. Passive force is divided into two kinds as well: a) a primitive passive force which constitutes the very thing and resembles scholastic idea of materia prima; and b) a derivative passive force which is found mainly in inertia and resistance of secondary matter.

Leibniz further develops his defense of plural notion of causality in his justification of metaphysics. He says that matter cannot stand by itself and that mechanism needs intelligence and spiritual substance, for it did not come from a material principle and mathematical reasons alone. Here he introduces a reflection on final causality. There is no doubt that for him God is the ultimate cause of everything in the universe. But he does not follow the occasionalism of Malebranche and acknowledges that God put into things certain properties which explain all their predicates. God’s eternal law is carried out by the activity of creatures.

hqdefaultThese developments of Leibniz’s metaphysics find another expression in his Monadology. The internal forces of monads can be identified with substantial form. When conceived as appetites, they have also a teleological character. The efficient causality of monads is not reciprocal. They cannot influence one another. That is why Leibniz introduces a rather vague idea of the principle of sufficient reason, which is supposed to explain the existence and relations between things (monads) apart from efficient causation (the meaning of both “sufficient” and “reason” is metaphysically unclear). The final cause of the order of monads and their characteristics is God. Although, according to his reflection in Monadology, efficient and final causality are complementary, Leibniz does not escape entirely the problem of determinism, which in his philosophy takes the form of a pre-established harmony.

David Hume (1711-1776)

Despite of Leibniz’s defense of formal and final causality, Descartes’ causal reductionism became more and more pervasive. It was followed by Locke, Newton, Berkeley, and Hume who is regarded by many as the one who gave the final blow to the theory of causation. While Berkeley argued against causal explanations (with reference to any kind of causation) in physical science, Hume generalized his opinion and applied it to natural philosophy and metaphysics, and thus did away with causality altogether. He claimed that given the concept of causal necessity, there is no way of justifying it rationally (causal necessity is not a logical necessity). He questioned three basic assumptions which he believed we accept in our notion of causation: 1) contiguity in space and time between cause and effect, 2) temporal priority of a cause to its effect, and 3) a necessary connection between cause and effect.

{D5079E92-F881-4CAD-98D4-BB94EE48752F}Img100In his Treatise of Human Nature Hume assumes that every idea in our mind is based on a prior impression. That is why in order to justify our idea of causation, we must find the impression that gave rise to it. The idea of necessity has its source in many instances of similar occurrences. It is an outcome of constant conjunction which produces an association of ideas in our mind. Hume emphasizes that the tie of necessary connection “lies in ourselves, and is nothing but the determination of the mind, which is acquired by custom,” and which we tend to project onto the world. Here he gives two important definitions of cause: 1) a cause is “an object precedent and contiguous to another, and where all the objects resembling the former are placed in like relations of precedency and contiguity to those objects, that resemble the latter;” 2) a cause is “an object precedent and contiguous to another, and so united with it, that the idea of the one determines the mind to form the idea of the other, and the impression of the one to form a more lively idea of the other” (A Treatise of Human Nature). Because causal relations are not logically necessary, they cannot be known a priori. In order to determine whether there is a causal relation between A and B we must rely on our experience of similar relations. Thus, constant conjunction or regularity is both necessary and sufficient requirement for causation. Especially if we assume that “we never can, by our utmost scrutiny, discover anything but one event following another” (An Enquiry Concerning Human Understanding).

But Hume’s metaphysical and methodological position, as well as his opinion about causation, are not as clear and transparent as it is usually assumed. First of all, his embrace of the radical empiricism is accompanied by some rational implications. While he states that the mind is concerned only with its own ideas and cannot perceive anything of the reality outside itself (radical empiricism), he adds at one point that all our distinct perceptions are distinct entities (strong realism). Considering Hume’s theory of causation, Don Garrett (“Hume” in The Oxford Handbook of Causation) points towards three possible interpretations of his position: 1) causal projectivism – a projection onto cause-and-effect pairs of an element of felt necessity that does not resemble anything in these pairs, and is derived from the experience of constant conjunction (causation is mind-dependent); 2) causal reductionism – causality is reducible to constant conjunction, but constant conjunction is not alone sufficient for knowledge of causal relations and we have to know, a posteriori, that constant conjunction is what the causal sense detects; 3) causal realism – it is possible to argue that Hume can accept causal cognitivism while rejecting the semantic reductionism that treats causal claims as synonymous with claims about constant conjunction. Garrett claims that Hume “concedes something to the motivations of each of these packages, and he could with some justice be classified as subscribing to any of them, or all of them, or none of them – depending on the details of the more specific definitions that might be proposed for them.”

Immanuel Kant (1724-1804)

bildKant found himself confronted with the rationalism of Leibniz and the empiricism of Hume, which he regarded as being in accord with Newtonian physics and philosophy, but incorporating to much of skepticism. Therefore, he was looking for a middle way which would implement both a priori elements of human knowledge stressed by rationalists, and the necessity of synthetic judgments based on the experience, emphasized in empirical circles. He sought a synthesis of these two approaches in a new type of judgment which is both synthetic and a priori. The price of this operation was significant. Since we can know a priori of things only what we ourselves put into them, synthetic a priori knowing “has to do only with appearances, and must leave the thing in itself as indeed real per se, but not known by us” (A Critique of Pure Reason).

Taking this position in his critical period Kant consequently and radically changes his way of philosophizing. While before Critique he was concerned with the problem as to how one substance acts on another, the problem of cause and effect, and the problem of space and extension as being constituted only by interaction of substances, in his present reflection substance as a basic explanatory principle is replaced by the a priori forms of sensibility and of understanding (he lists 12 of them). They are understood as the conditions of the possibility of experience, and are valid a priori for all objects of experience.

kants-thinking-capFollowing this methodological strategy Kant wanted to ground the principle of causality in the structure of reason. But in order to avoid the epistemologically disastrous consequences of the Humean criticism, he classified it as a principle explaining the synthetic a priori judgments of science. An event A is the cause of an event B iff there is a universal law which says that events of type A are necessarily followed by events of type B. But because neither the necessity nor the universality of the causal relation can be established empirically, it has to be grounded in the a priori conditions of judgment of a possible experience. Thus we can see that Kant rejects Hume’s view that we first perceive temporal succession between events, and only afterwards we are able to name one of them as cause, and the other as effect. For him the opposite is true. In order to establish an objective order of events in time, we need a priori synthetic concept of cause-effect relationships.

Summing up, we can say that Kant thought he have proved that concepts such as “cause” (“substance,” etc.) “stand a priori before all experience and have their undoubted objective rightness, though admittedly only in respect of experience” (Prolegomena to Any Future Metaphysics). For him every occurrence has a cause which is a prior event. The effect follows from the cause necessarily, and in accordance with a rule which is absolutely universal. All this is known to us a priori, but not without reference to experience.

Auguste Comte (1798-1859)

auguste_comte_grandeDespite of Kant’s struggle to save causation in epistemology and scientific explanation, the positive method in science and philosophy followed the way proposed by Berkeley and Hume, disposing of the search for causes. Positivists, in place of causes, searched only for correlations between facts which can be expressed in general laws of phenomena. Auguste Comte, who is one of the main representatives of the positivist camp, formulates his famous law of three stages: 1) theological or fictious, in which mind seeks the essential nature of beings, 2) metaphysical or abstract, in which mind replaces supernatural agents with abstract forces, and 3) scientific or positive, in which mind gives over the vain search for absolute notions and studies laws of natural phenomena (The Course in Positivist Philosophy). Although he endorsed the use of hypotheses, Comte accepted them only provided they were open to empirical verification. He stressed prediction rather than explanation as science’s primary aim. At one point he speaks very bluntly, leaving no doubt as to what he thinks about causal explanation: “The basic characteristic of the positive philosophy is that it regards all phenomena as subjected to invariable natural laws. Our business is – seeing how vain and senseless is any search into what are called causes, whether first or final – to pursue an accurate discovery of these laws, with a view to reducing them to the smallest possible number” (The Course).

In spite of his radical rejection of causality, Comte did not reduce his “positive philosophy” merely to induction. He still valued deduction for establishing particular conclusions related to special topics of research, and as an essential tool of making predictions. For this reason, we can venture to say that Comte in fact followed the path of those post-Cartesian philosophers who hoped to steer a middle course between empiricism and rationalism. Nevertheless, it seems that nothing was really able to change the course that philosophy of science took after Descartes, which led to the decline and final dismissal of causal explanation in phenomenalism, conventionalism, operationalism, and the orthodox interpretation of quantum mechanics. However, the story does not end up with these trends in philosophy. Causality is coming back on stage with anti-Humean tendencies and the return of realism, accompanied by some contemporary reflections on causality within the analytic tradition. But this is a material for yet another story.

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Philosophy of Causation – Vol. 1 – Ancient Greece

I have recently accomplished my Special Comprehensive Exam which is a major step on the way of my doctoral studies at the GTU in Berkeley, CA. The first part of the project was a written exam which covered some of the major developments of the theory of causation in ancient, medieval, and modern philosophy. In this post I publish the first part of the exam, the one referring to the ancient tradition. I hope the readers of my blog will find it interesting. Remaining parts are to come soon.

change

The development of the reflection on causality in ancient Greece has its beginnings in the philosophy of early Milesians, who presented three positions on the problem of change in nature. According to the first and predominant option some things change (totally or in some ways), while other things do not go through the process of change. Noticing this, some of the philosophers looked for a fundamental principle which does not change and remains constant. Thus, we can say that they gave the origin to the reflection on material cause. Thales (620-550 BC) claims that the fundamental constituent which remains unchanged is H2O. It can exist as solid, liquid or vapor. Hence, all things are water in various states. Anaximenes (570-500 BC) takes air for the basic stuff and says that everything is really air in different forms of rarity or density. Anaximander (610-525 BC) takes an important step saying that none of the basic elements (earth, fire, water) can be the first principle for it would destroy other elements. He enters a meta-level of philosophical reflection saying that the undetermined principle is most fundamental and may be called “the infinite.” It is by joining and separating of opposite qualities present in “the infinite” that all things come into being and change. (Michael Dodds rightly says that if we substitute “energy” for “air,” Anaximenes becomes Einstein. Heisenberg saw Anaximander’s “infinite” equivalent to “energy” in modern physics. Dodds argues that his description is closer to Thales: instead of H2O we have “matter” or “energy.”)

perpetual-ocean-world-currents-atlantic-cuba-haiti-dominican-republic-jamaica-bahmas-florida-cape-tip-stop-motion

The second view of change among early Greek philosophers is represented by Heraclitus (fl. 500 BC) and assumes that all things are constantly changing. Things are just ephemeral patterns of continuity in the perpetual flux of the world. (Dodds finds this position similar to the contemporary philosophy of process). The third view represented by Parmenides (fl. 500 BC) remains in opposition to the former one, as it assumes that nothing really changes in nature. Things either “are” or “are not,” there is no other option, and thus nothing can change. For a new thing could come into being only from non-being (which is impossible), or from being (which would mean that it existed before). Therefore, change is an illusion.

The conceptual level of Anaximander’s reflection (as distinct from more empirically grounded philosophy of other Milesians) finds its continuation in Anaxagoras (c. 510-428 BC), who declares cosmic intelligence (mind, nous) to be what causes everything. But since intelligence seeks what it values, this kind of explanation exceeds an interest in material cause, predominant among Anaxagoras’ predecessors, entering the new level of explanation, which is teleological in style. Hence, we can find here the first primitive notion of final causation. However, Plato (Socrates in Phaedo) claims that the details of Anaxagoras’ reflection show that he was not aware of this commitment (he concentrates mainly on materialistic factors such as air, water, and vortex).

The further step on the way of defining causality was taken by Empedocles (ca. 495-435 BC) who presents the first reflection on efficient cause. He claims that besides the elements of earth, air, fire, and water, two further elements, “love” and “strife” are needed in order to combine or keep apart the basic elements. The idea of efficient cause was developed later on by Democritus (ca. 460 – ca. 370 BC) and atomists, who would remain in opposition to the idea of final cause of the universe, arguing in favor of the purely mechanical view of causation (movement and collisions of atoms).

Pythagoras

Among the earliest philosophical schools we find one more which remains at odds with those described so far. It is the school of Pythagoras (ca. 570- ca. 490 BC), who was the first to make an attempt to understand the cosmos and its phenomena in terms of number. His reflection was rooted in Egyptian geometry and Babylonian arithmetic. Pythagoras used them to develop a philosophy of nature based on mathematics. He suggested a parallelism between the idealizations of geometry and the physical patterns of the universe. According to him, number underlines all physical objects and its study reveals deeper level of reality than is apparent on the surface. Aristotle would say, later on, that Pythagoreans considered number to be the principle of both matter (even or “unlimited” elements of number) and form (uneven or “limited” elements of number). Thus, every physical entity is explainable in terms of mathematics. From this basic point the Pythagoreans went to a detailed study of mathematical proportions, harmonic relationships, and irrational numbers, which gave the origins to a study of continuum and infinite divisibility.

Penrose tiles

Pythagorean ideas combined with Democritus’ atomism inspired Plato (428/427 or 424/423 – 348/347 BC) to present his geometric theory of matter. The originality of his theory is based on the fact that he regards matter (“the mother of all becoming”) as a stable and eternal receptacle for Ideas of Forms, and thus formulates the first notion of formal causation. He is also probably the first one to state explicitly the principle of causality in Timaeus: “everything that becomes or changes must do so owing to some cause; for nothing can come to be without a cause.” For Plato the world accessible to our sensual experience is changing and made of appearances. It is merely a shadow of the true reality which is the world of autonomous and immaterial Forms. If the formless matter is “the mother,” the eternal form is “the father,” and the transitory phenomena known to our senses are their offspring. The elements of the physical world are construed on the model of geometrical patterns: fire takes the shape of tetrahedron, air of octahedron, and water of icosahedron. All of these shapes are made of multiplied triangles. Therefore, the triangle can be regarded as an atomic element in Democritean sense.

What remains crucial for our further reflection is the fact that neither Pythagoras nor Plato regarded mathematics, as did Aristotle, as a formal and abstract discipline which applied to reality enables us to construe a subalternated type of scientific knowing, abstracted from empirical and sensual experience. They saw it rather as a way of arriving at the ultimate and basic reality itself, which in sensual experience is given only in ephemeral appearances.

aristotle

Aristotle (384-322 BC) presents the most developed theory of causation among philosophers in ancient Greece. He systematizes and further develops the teaching of his predecessors, defining four kinds of causality in Posterior Analytics, Physics, and Metaphysics (he alludes to various causes in other works as well). Material cause for Aristotle means not only the basic building stuff. He introduces the term of primary matter (prōtē hulē) which he understands as a principle of potentiality, something that persists through all changes that a given substance can be exposed to (something that constitutes the very possibility of being a substance at all). Concerning formal cause, Aristotle remains in a radical opposition to the transcendental character of Ideas in Plato. For him forms must be in things, determining their actuality. Formal cause answers the question “why” something is the kind of a thing it is, and it cannot be reduced to “shape” or “appearance” of a thing. Aristotle introduces also an important distinction between accidental and substantial form, which he explains in terms of changes that effect in an “alteration” (an accidental change), which does not change the substantial principle of a substance, as opposed to a situation in which the thing changes as a whole (coming-to-be of a new substance). For Aristotle material and formal types of causation are intrinsically related. They can be separated only in mental reflection. In reality we know primary matter only as informed, and form only as informing primary matter.

The other two causes indispensable for Aristotle’s description of reality are: efficient and final. The former one is generally defined as an activity of an agent bringing motion or rest. However, Aristotle classifies as efficient causality also activities such as giving an advice, which in some of its aspects goes beyond physical interaction and exchange of energy. The latter, final cause, he defines as “that for the sake of which” a thing is done, or a good proper for a thing that can be attained. It is important for him to notice that final causality should not be associated merely with conscious and rational human decisions. He speaks about natural teleology which is present both in inanimate and animate nature even if it “does not deliberate.” Finally, Aristotle emphasizes the relation between efficient, formal, and final causation, noticing at the same time that final cause is the first and should be regarded as causa causarum.

monkey-with-name-chance-md

Aristotle devotes no less than three chapters of the second book of Physics to the study of chance and necessity. He criticizes philosophers of the past for either not finding a place for chance on their list of causes, or not paying enough attention to it. He refers specifically to Empedocles who attributed to chance certain events, such as movement of air in the process of the separation of elements, or the origin of the parts of animals, but did not analyze the nature of chance in more detail. He is also critical about Democritus who attributed the origin of the universe to spontaneity, claiming at the same time that chance is not responsible for the generation of plants, animals, or mind. Such an explanation ascribes the causes of things to both necessity and chance, understood as the “absence of purpose.” Following this line of thinking, Plato (Timaeus) saw both necessity and chance as inherent in the material cause, which is formed by the Demiurge (reason) who strives to prevail over necessity of matter resistant to order. Because the reason cannot succeed fully in its endeavor, chance events occur which show no order.

Contrary to Empedocles, Democritus, and Plato, Aristotle claims that necessity, which implies order, is irreconcilable with chance, which occurs contrary to a given order. Thus, Aristotle distinguishes chance events from occurrences that happen necessarily, and those happening in the same way for the most part. Chance events also have a unique character in his second classification, in which Aristotle distinguishes between events that come to be for a purpose (due to a deliberate intention or as a result of nature), and those that do not happen for a purpose. He says that “even among the things which are outside the necessary and the normal, there are some in connection with which the phrase ‘for the sake of something’ is applicable. (…) Things of this kind, then, when they come to pass incidentally are said to be ‘by chance’.” In reference to his distinction between per se and per accidens causality Aristotle states that chance is an unusual accidental cause, and as such it is inherently unpredictable, although it still falls in the category of events that “happen for the sake of something.” Although chance events are due to nothing in the substance or per se cause which happens to concur with these unexpected occurrences, as an accidental cause, chance occurs always and only in reference to per se causes. Therefore, chance occurrences for Aristotle are always posterior and inherently related to nature (φύσις) and intellect (νοῦς). Hence, they are associated with formal and final causality rather than material necessity.

regularity

The ancient philosophical reflection on causality notes one last important contribution brought by Stoicism (3rd cen. BC), which would have a major influence on the development of modern accounts of causation. Stoics linked causality with exceptionless regularity and necessity. We can list five of their most basic theses concerning causation: 1) Cosmos is an organism imbued with divine reason (logos) and ordained by fate; 2) Nothing happens without a cause; 3) Causation involves exceptionless regularity; 4) All particular events necessitate their effects; 5) There is a fundamental distinction between external and internal causes. The last rule seems to be an answer to a controversy concerning human freedom which appears to be undermined in Stoicism (Cicero, De fato). An external cause is only auxiliary and proximate while an internal cause is called principal and perfect. Every human action is a response (based on internal cause) to an external cause producing sense-impressions. The consistency of this theory is questionable, and the action of human being in Stoicism seems to depend entirely on determinism of nature and fate.

Summing up, we can see that the ancient tradition offers a variety of approaches to the problem of causation. It developed a fourfold division of causes defined by Aristotle which will prove to have a substantial influence on medieval philosophy of nature and its steps towards understanding of the world and its processes, opening the way to natural science of modernity.