Protreptikos a publication of Introduction to Philosophy

Monism and Pluralism

Monism (from greek monos - monos - one) is a term that describes any philosophy that denies that there are many separate beings in the universe. The early Greek philosopher before Socrates (pre-Socratics) generally tried to explain the physical universe by one simple thing. The most radical monism is that of Parmenides, who said that all that exists is being, and therefore all is one. Either being or non-being, and since non-being does not exist, there is only being. Parmenides denied the evidence of the senses, that tell us there are many beings. Parmenides even denied the evidence of the senses, saying that even the distinction between the knower and the known, between the thinker and the object of thought, are illusions (tauton de esti noein te kai ouneken esti nohma - tauton d' esti noein te kai houneken esti noema - the same thing is the thinking and what the thought is about; to gar auto noein estin te kai einai - it is the same thing to think and to be.)(1) Heraclitus held the opposite view, that there is no permanent being, only change, but he was also a monist in his own way, saying that everything is change. Socrates (470-399 BC)and his disciple Plato (428-348 BC) did not deny the reality of the real world, and so they were not pure monists, but they did think that material things had less reality than the ideas of those things. The ideas existed in a higher way, and all the ideas were connected together in the highest idea of the one and good.

The atomists, such as Democritus (c. 460-360 BC), Leucippus, and Lucretius(2), did not say that there was one being, but that there was really only one kind of being, the atom (atomos, atomos, individisible) All things can be reduced to small indivisible particles that could not be changed in any way except their position in space. The combinations of atoms in space could explain (explain away!) everything. Free will was accounted for by a mysterious swerve in the movement of atoms through space. The view that physical reality can be reduced to the movements of indivisible particles was accepted by scientists after the time of Newton, and was only rejected early in this century.

René Descartes (1596-1650) was himself a dualist, saying that there were two kinds of realities(3) -- res cogitans or thinking thing, and res extensa or extended thing -- but his system would lead to a kind of monism that is based on a thinker who knows only his own thoughts and cannot reach any reality outside his own self.

Bishop George Berkeley followed Descartes' method, saying that the fact of knowledge was the most evident reality. He is famous for the saying -- esse est percipi, to be is to be perceived. (4) He argued that we can never affirm that anything exists, unless we know about it by some sort of perception. It is impossible to think of anything except in relation to our own mind. His argument can lead to solipsism solus - alone, unique ipse -self), the view that I alone exist.

Immanuel Kant (1724-1804) taught that the outside world is unknowable, and that our perceptions of time, space, and the relations of cause and effect, do not come from reality but from the structure of our own mind.(5) Time, space, and cause-effect are not realities, but they are a priori categories (like the software of our mind). Later German philosophers did away with the whole idea of an outside world, since according to Kant it was unknowable anyways, and talked about the "I" as it divides itself into the thought of self and the thought of non-self (Fichte), or about the evolution of ideas in human consciousness (Hegel), or they tried to withhold judgement about reality and simply to describe consciousness (the phenomenologists, notable Max Scheler and Edmund Husserl).

Composition in Being

However, our common experience tells us that we live in a world of many real beings. I am only one of those beings. These beings can be understood according to their different natures, and they come into being and go out of being. This position is called pluralism (plures - many more). The universe has unity, but not the unity of one thing, but the unity of many things that have the fact of existence in common. Aristotle and Aquinas explained the pluralism of beings by composition. None of the beings of our experience is an absolute being, but is limited in various way. Composition in being is the presence of two elements that go together in one thing. There are four basic kinds of composition in classical philosophy:

  1. act/potency;
  2. accident/substance;
  3. form/matter;
  4. existence/essence.
The most basic type of composition is that act and potency.

Act and Potency

Act (actus) means the same as action in everyday language.(6) Philosophers apply this term in a special way, because they recognize that the primary action of any real thing is to exist. "To be" or "to exist" is a verb. Existence is the primary act of any real thing. All the other acts, expressed as verbs, are secondary acts, because they are based on the thing's existence and nature. This primary act of existence differs from all other acts because it is completely analogical. For each thing, its act of existing makes it what it is in reality. For myself, "to be" means to be me, and not you, and not another kind of thing. So, although you and are are "doing the same thing" by existing, we are also doing different things, otherwise for me to be would be the same as for you to be.(7)

Potency (potentia) is what a thing can be or can do, but is not actually doing. Potency is derived from posse, which is the Latin verb can or to be able.Philosophers say that a thing has a potency to something, which means that a thing has the ability to change into something. Potency in the primary sense is passive. It means that a thing can have a fuller existence if something else acts upon it. For example, we might say that a child has great potential, but that potential won't be realized or actualized unless other factors act upon the child. Passive potency is between being and non-being. Potency cannot exist all by itself, but exists in an actual subject and it is always ordered to some act. Matter is pure passive potency, because matter can take on any form, but it needs to be acted upon by something. Nothing moves from potency to act unless some agent acts upon it.

The Absolute Being is pure act without any mixture of potency, since potency is like an emptiness. We might say that the supreme being has no potency, but this refers to passive potency. Active potency, the ability to act, can be found in the Absolute Being.

Thomas Aquinas' first proof for God's existence is based on Act and Potency. A thing that is in potency to change must be acted upon by something which is in act. Ultimately, this leads to the existence of a Being which is in pure act.(8)

Matter and Form

Matter and Form are two components of every material being.(9) Matter cannot exist without form. Matter is the principle of potency in a material thing, and form is the principle of actuality. Matter is what makes change possible. One self-evident principle is that in every change something must stay the same.(10) When things change, for example, when a log burns or a plant grows, there are not simply two separate and unconnected realities, one before and the other after, but the matter stays the same, while it loses one form and takes on another. On the other hand, one and the same thing can remain in its identity while the matter comes and goes. Matter is either primary (when we think of matter as something that can go through all possible changes) or secondary (matter as already possessing some form and ready to take on a new one). In a living thing, the form is called a soul as the principle of life, which informs matter. A living body is matter and form. Without the form called soul (anima in Latin, yuch - psyche in Greek), there is no living body, just a collection of matter. The form of a thing is the source of its activities. The form of a thing sets one thing apart from another, so that we can understood it as belonging to a particular type of thing.

Form does not mean the same thing as shape. Since the form of a thing is the source of its activities, we know about form by looking at activities. Something may have the shape of a dog, but only a real dog acts like a dog. We know a real dog from the way it acts. This is expressed in the axiom operari sequitur esse - operation follows existence. This means that the way a thing acts is a consequence of its mode of existence, or of its form or nature. Now, if we look at the human being in this way, we see that a human being is capable of some actions that transcend matter. Intellectual understanding and will or love are not merely material acts. The mind can grasp meanings, and meaning itself cannot be explained as a mere arrangement of physical elements without the fallacy of a circular argument (since any such explanation will use other words, which in turn have meaning). If the human being is capable of immaterial or spiritual acts, then he has a very unusual form. The human soul is a form that makes matter into a living body, but it is more. It is a subsistent form. If it is capable of immaterial acts, then it has an existence that cannot be destroyed, because only material things can be destroyed.

Form is either substantial or accidental. The substantial form of a thing expresses its identity through all the time of its existence. Accidental forms are aspects of a thing that come and go. This leads us to the next composition, that of substance and accidents.

Substance and Accidents

Substance means the underlying reality of a thing (sub - under; stare - to stand). (11) It can mean the thing itself in its most basic reality. Accidents are modifications of the reality of a substance that come and go. Aristotle listed nine basic types of accidents:

  1. quality;
  2. quantity;
  3. where;
  4. when;
  5. relation;
  6. action;
  7. passion;
  8. disposition (arrangement of parts);
  9. habit or possession.
Substance is called ens in se -- being in itself. An accident is ens in alio -- a being in something else, because an accident cannot have independent existence. The accident of relation is called ens ad aliud -- a being toward something else.

Only substances are fully real existing things. Only a substance can perform an action. This is expressed in the dictum -- actiones sunt suppositorum -- actions belong to subjects (suppositum is another term for substance or subject). The philosopher Boethius defined a person (a human person or any other, such as a pure spirit) as individua substantia rationalis naturae -- an individual substance of a rational nature. Only a person can be the subject of rights and duties, and only a person can act with freedom and knowledge. A common error is to ascribe to something which is not a substance actions or attributes that can only belong to a real individual. For example, the economy, state, war, family, are examples of relations between real substances. The economy does not do things, people do. War does not break out, someone gives the order to engage in hostilities.

Substance is related to accidents as potency to act, because a substance may be completed or perfected by accidents. For example, knowledge is an accident of the person who knows, as a relation to reality, a passion because he is affected by reality, as an action because he performs an action to understand, and a habit because he possesses knowledge.

Essence and Existence

Essence is what a thing is.(12) Essence is also called nature (from nasci -- to be born) to indicate that the essence of a thing is the source of its activities. Essence is called quiddity or whatness (from quid -- what), to show that essence is what we describe when we answer the question "what is it?". Existence is the fact that a thing is. It is called the act of being. Existence is the fact that a thing is. This distinction is related to the distinction between necessary and contingent (or possible) being. A necessary being is something that must exist by virtue of its own nature. A contingent being is something that depends upon something else for its existence. There is nothing in the nature or essence of a contingent being that says that it must exist. The Arab philosopher Avicenna (Ibn Sinna) reflected philosophically on the meaning of God's response to Moses' question. When Moses asked Him what his name was, He answered "I am who am". Avicenna understood this as meaning that God is the Being who must exist, therefore a Necessary Being (Necesse Esse). Other beings in relation to God are merely possible (Possibile Esse), because compared to God they are merely possibilities that may or may not be actualized. Thomas Aquinas draws on this in his third proof for the existence of God.(13) If all the beings we see are contingent, then they can go in and out of existence, and at one time there could have been nothing. We might think that matter remains while things come and go, but we still must ask, is there anything in the nature of matter itself that says it must exist, and the answer is no. There is no reason in matter itself why ther e should be more of it or less of it, or none at all. If all the things we can see are contingent, there must be a necessary being from which they receive their existence. God is described as a being whose Essence and Existence is one and the same. It is his "nature" to exist.


1. Diels, fragments 4, 3.

2. cf. Stumpf, pp. 420-432 on the atomism of Democritus, Leuccipus, and Lucretius, and Sir Arthur Eddington's modified atomism (atoms are just mental tools but cannot be described in everyday terms).

3. cf. Descartes, Meditations, in Stumpf, p. 454-455.

4. George Berkeley, Three Dialogues between Hylas and Phylonous, (Stumpf. P. 433-444).

5. Immanuel Kant, Critique of Pure Reason (Stumpf p. 298-308).

6. Potency and Act are discussed in Aquinas, On the Principles of Nature (Bourke, p. 61-77); Summa contra Gentiles, II, 54 (Bourke p. 169); Disputed Questions on Truth XVI, 1, ad 13 (Bourke, p. 172).

7. Vaske, p. 13-14.

8. Aquinas five ways of showing God's existence, Summa Theologica, I, q. 1, art. 3 (Stumpf 379 ff).

9. Aquinas on matter and form in living things: Commentary on Aristotle's De Anima, II, 1 (Bourke 97-104); Summa Theologica, I, q. 75 a. 5, q. 76, a. 1 & 4 (Bourke, 112-117).

10. cf Vaske, p. 14.

11. Aquinas on substantial and accidental forms: Disputed Questions on Spiritual Creatures 1 ad 9 (Bourke 175-177).

12. Aquinas on essence and existence: On Being and Essence (Bourke 152-158).

13. Summa Theologica, q. 1, a. 3 (Stumpf 379 ff).