Thomas Hobbes on Accidental and Essential In “Leviathan”

In his book “Leviathan”, Thomas Hobbes prefaces his discussion of politics and the “social contract” with a discussion “Of Man”. ( (My references to “Leviathan” are to the Penguin Classics version, 1987, ISBN 0-14-043195-0 )

Hobbes recognizes that one must study the nature of man before discussing how men should be organized into society and what sort of political system they should adapt. He also recognizes that the nature of the human mind, and how it acquires knowledge, is key to understanding the nature of man.

In historical context, Hobbes lived in a time when some of the scientific assertions of Aristotle, which had been re-incorporated into Western thinking by Thomas Aquinas, were being questioned.

Galileo Galilei had presented evidence that tended to overthrow the Ptolemaic system, which had described the Earth as the center of the universe. This idea had become official doctrine of the Church with its adoption of Aristotle, through Thomas Aquinas, at the beginning of the Renaissance.

Hobbes wrote against this backdrop, in which all of Aristotle’s science, especially his cosmology, was starting to be questioned.

Despite his declared rejection of Aristotle, Hobbes didn’t go far enough in questioning the philosopher when it came to the distinction between “essential” and “accidental” properties of a thing. (

Although Hobbes was right to reject the Platonic/Aristotelian view of “essences”, his embrace of the idea of “accidental” features in things that are not man-made lead him to believe that definitions are based on mere “accidental” features.

An alternative to both Hobbes and the “realists” (Plato and Aristotle) holds that essential features are characteristics perceived by a particular type of mind, the human mind, to serve human purposes -ultimately, man’s life.

There is a long-standing debate in the history of philosophy about where the essential feature(s) that comprise a concept come from:


“Since man’s knowledge is gained and held in conceptual form, the validity of man’s knowledge depends on the validity of concepts. But concepts are abstractions or universals, and everything that man perceives is particular, concrete. What is the relationship between abstractions and concretes? To what precisely do concepts refer in reality? Do they refer to something real, something that exists -or are they merely inventions of man’s mind, arbitrary constructs or loose approximations that cannot claim to represent knowledge?…To exemplify the issue as it is usually presented: When we refer to three persons as ‘men’, what do we designate by that term? The three persons are three individuals who differ in every particular respect and may not possess a single identical characteristic…If you list all their particular characteristics, you will not find one representing ‘manness.’ Where is the ‘manness’ in men? What, in reality, corresponds to the concept ‘man’ in our mind?” (Ayn Rand, Introduction to Objectivist Epistemology, 2nd Ed., “Forward to the First Edition”. New York:Meridian (1990).)

Plato said that “essences” exist in pure form in some other realm, and that the world we see around us is just a vague, shadowy approximation of that real world of forms. This is probably what was meant by Plato’s “Allegory of the Cave”

Plato said we are all like people who are chained and forced to face the wall of a cave with a fire behind us. We can see the shadows of people and other things as they pass by, but we cannot see the actual things. This is a metaphor for the idea that human senses do not perceive actual entities or things, just the shadows of things that actually exist. What actually exists are the “forms”, which are in some other realm. Human beings are merely perceiving the shadows of those forms. Those “forms” are what we mean when we speak of the essence of a thing. The “manness” that we perceive in men actually exists in some pure form in another realm, and the individual men that we perceive are just shadowy approximations of the “Platonic form” of man.

Plato’s student, Aristotle was somewhat more “this worldly” than his teacher. Aristotle rejected the idea that “forms” exist in some other realm. Instead, some scholars interpret Aristotle as saying that the “form” or “essence” of a thing exists within each concrete instance. The practical result of this would be that for Aristotle, studying concrete particular things is important to understanding them, since that “essence” of the thing exists somewhere within it, whereas Plato said the “essence” isn’t in the thing –the thing is just a shadow of that “pure essence”. Plato’s view of knowledge would tend to suggest that one gains knowledge by learning about some other world, other than the one you perceive, while Aristotle at least believed that you should study the things you can actually see and perceive in order to learn about their essence.

Starting in the late Middle Ages, the ideas of Aristotle were rediscovered by Western Scholars like Thomas Aquinas. By the time of the Renaissance, much of Aristotle had been incorporated into Church doctrine. The ideas of Aristotle and Aquinas became part of the “scholastic” tradition.

In the 1600’s, Hobbes, and other thinkers and scientists, began to reject the ideas of the “Schoolmen” (the Scholastics).

“Lastly, the Metaphysiques, Ethiques, and Politiques of Aristotle, the frivolous Distinctions, barbarous Terms, and obscure Language of the Schoolmen, taught in the Universities, (which have been all erected and regulated by the Popes Authority,) serve them to keep these Errors from being detected, and to make men mistake the Ignis Fatuus of Vain Philosophy, for the Light of the Gospell.” (Leviathan, Pg. 708)

Along with the doctrines of Aristotle, Hobbes also denounced, amongst others, the idea of Papal infallibility (“…that the Pope In His Publique Capacity Cannot Erre…” Leviathan, Pg. 706) and transubstantiation (“…they assure the same, by the Power they ascribe to every Priest, of making Christ; and by the Power of ordaining Pennance; and of Remitting, and Retaining of sins.” Leviathan, Pg. 708)

Hobbes likely regarded Plato’s Allegory of the Cave as an “abuse of speech”:

“Secondly, when they use words metaphorically; that is, in other sense than that they are ordained for; and thereby deceive others.” (Leviathan, Pg. 102)

The allegory of the cave could be considered a “metaphorical” use of words, aimed at deceiving others into doubting the evidence of their senses.

If Hobbes rejected the essentialism of Plato and Aristotle, what did he believe we were referring to when we speak of an essential, defining characteristic of a thing?

For instance, I read an article about a chimpanzee that lost all of his hair in a zoo because of alopecia –a disease. (

This is what Hobbes says the schoolmen would say:

“From these Metaphysiques [the philosphy of Aristotle], which are mingled with the Scripture to make Schoole Divinity, wee are told, there be in the world certaine Essences separated from Bodies, which they call Abstract Essences, and Substantiall Formes…” (Leviathan, Pg. 689)

Aristotle tried to draw a distinction between “essential” and “accidental” properties of a thing to account for something like a chimpanzee without hair, and why it is still a chimpanzee. (

The fact that most chimpanzees have hair on their bodies must be an “accidental feature” of a chimpanzee. Something else must be “essential”.

Although he is not always clear on this point, I believe Hobbes thought all definitions ultimately rest on “accidental qualities”:


One Universall name is imposed on many things, for their similitude in some quality, or other accident: And whereas a Proper Name bringeth to mind one thing onely; Universals recall any one of those many. ” (See Leviathan, pg. 103)


In the above passages, Hobbes says there are “accidental qualities” that make up “matter” and “body”. Hobbes initially did seem to suggest that one “…Universal name is imposed on many things, for their similitude in some quality, or other accident…” (Leviathan, Pg. 103)

This could be interpreted as meaning he made a distinction between “similarity” and “accident”. So, for instance, the chimpanzee with alopecia has no hair as a result of an “accident” (a disease). However, given what he then gives as examples of “accident” (“living”, “moved”, “hot”, “long”, etc), the logical implication is that all characteristics of any given entity would ultimately be considered “accidental”.

Additionally, for Hobbes, a “body without us” is what is commonly called an “object”. “Objects” are the things we perceive with our senses:


Every “object” that we perceive, according to Hobbes, is a “Representation” of “Apparence” of “some quality, or other Accident of a body [an object] without us; which is commonly called an Object.”

The logic of Hobbes’ view of knowledge is to say that everything about a particular entity that we call “matter” or “body” is just an accidental feature. Therefore, all of our concepts must be based on “accidental features”. There is no “essence”, as Plato or Aristotle speaks of them.

One of the strengths of Hobbes is his commitment to good definitions:



Here, Hobbes says that all authority must be rejected (specifically the authority of “…Aristotle…Cicero…[and]…Thomas [Aquinas]…” He says that one must “…examine the Definitions of former Authors…” to see if they are right or wrong. Hobbes says that failure to do so will cause one to “…find himselfe entangled in words…”

But, Hobbes doesn’t always follow his own advice on definitions. Hobbes uses the term “accidental” without thinking about what that means -what its definition is. The definition of “accident” is:

“an event that is not planned or intended: an event that occurs by chance” (

An “accident” means something that was not planned or intended. With respect to “the metaphysical”, i.e., all aspects of reality that don’t involve human choice, the concepts of “planned” or “intended” do not apply. Only human beings, and, arguably, certain other types of living organisms, are capable of “planning” or “intent”. These concepts pertain to entities that possess a mind like human beings.

Similarly, the concept of “chance” means that an event occurs about which one does not have sufficient information to know for certain what the outcome will be. For instance, if I flip a coin, whether it will come up heads or tails is a question of “chance”, and I can speak of the probability that it will come up heads or tails.

If I had enough data about the original position of the coin prior to being tossed, the angle(s) and speeds of all the forces that worked on it when it was tossed, the wind and weather factors involved, etc., then I could know for certain whether the coin toss would end up heads or tails. It would no longer be a matter of “chance” because I have sufficient knowledge to know all the factors that are playing into its eventual resting state.

All inanimate things act in accordance with their nature, and the nature of other things that they interact with, and they absolutely must act that way. “Chance” is just a way of saying that a human being doesn’t have enough knowledge about the nature of certain inanimate things to know what the outcome will be.

For example, the fact that the Earth and the other planets came to revolve around the sun the way they do, and at the orbits they occupy, had to occur that way because of the nature of the Sun and the other planets. (Their masses, their speeds, their composition, etc.) The element of “chance” comes into play because human beings do not know all of the factors that led to the Earth orbiting the sun in the way it does. “Chance” is just a reflection of some human being’s level of knowledge on a subject.

As far as we know, only human beings make choices. Since only human beings can make plans or intend to bring about some event or goal, only human beings are capable of having their plans or intentions fail due to some ignorance, negligence, or irrationality on their part. Only human beings can have “accidents”, because only human beings can be mistaken.

This means that when it comes to reality, apart from those aspects that don’t involve human choice, nothing is “accidental”, because the concept does not apply. It’s like asking: what is the sound of one hand clapping? Or: what is outside the universe? Since clapping, by definition, is the striking together of two hands, it is a nonsense sentence. If the universe is all that exists, then you cannot speak of anything “outside” it, because anything that exists is part of the universe. “Outside” is also a relational concept, implying that something that exists is not within something else, so there is no “outside” the universe. (Arguably, there is no “inside” the universe, either.) Similarly, speaking of “accidental” aspects or features of reality, that don’t involve human choice, is a nonsense statement.

Going back to the chimpanzee with alopecia, the fact that he lost all of his hair is not an “accident”, nor is the fact that other chimps have their hair an “accident”. Chimps that don’t have alopecia have their hair because of their nature as a living organism, plus the nature of the rest of reality that they interact with. It isn’t an “accident” that chimps have hair. It had to be that way, because reality is what it is. There is no god making choices about how reality is going to be. Reality simply is. Only human beings make choices, that we know of, and only human beings can make plans. Human beings, not reality, are capable of having “accidents” -of making mistakes. If a chimp looses his hair for some reason that doesn’t involve human choice, it had to be that way because of the nature of certain diseases and the nature of the chimp’s body in reaction to those diseases.

What is the consequence of believing, as Hobbes appears to, that all features or characteristics of “matter” and “body” are “accidental”? He would have to believe that all concepts that human being hold must be, in some sense, “accidental”. Concepts for Hobbes are not going to be fully real to him. Hobbes is what is known today as a “nominalist”:

“Denying that concepts have an objective basis in the facts of reality, nominalists declare that the source of concepts is a subjective human decision: men arbitrarily select certain characteristics to serve as the basis (the “essentials”) for a classification; thereafter, they agree to apply the same term to any concretes that happen to exhibit these “essentials,” no matter how diverse these concretes are in other respects. On this view, the concept (the term) means only those characteristics initially decreed to be ‘essential’. The other characteristics of the subsumed concretes bear no necessary connection to the ‘essential’ characteristics, and are excluded from the concepts meaning.

Observe that, while condemning Plato’s mystic view of a concept’s meaning, the nominalists embrace the same view in a skeptic version. Condemning the essence-accident dichotomy as implicitly arbitrary, they institute an explicitly arbitrary equivalent. Condemning Plato’s ‘intuitive’ selection of essences as a disguised subjectivism, they spurn the disguise and adopt subjectivism as their official theory…Condemning Plato’s supernaturally determined essences, they declare that essences are socially determined, thus transferring to the province of human whim what had once been the prerogative of Plato’s divine realm. The nominalists’ ‘advance’ over Plato consisted of secularizing his theory.”(Leonard Peikoff, “The Analytic Synthetic Dichotomy.” In: Rand, A. Introduction to Objectivist Epistemology, 2nd Ed.” New York:Meridian (1990).)

Hobbes is correct that all definitions of concepts rest on human choices -that all essences are based on human choice. He is mistaken in believing that certain aspects or characteristics of the things we perceive, given certain contexts of knowledge, should be considered no more essential than all of their other features, though. This is because the human mind has a certain nature, and it must organize the material it perceives in accordance with that nature if it is going to function effectively. Since human thought serves human life, certain characteristics of the entities we perceive are more fundamental than others, because we adopt certain principles of “fundamentality” that serve our nature as living beings with a certain nature of mind.

“Now observe, on the above example, the process of determining an essential characteristic: the rule of fundamentality. When a given group of existents has more than one characteristic distinguishing it from other existents, man must observe the relationships among these various characteristics and discover the one on which all the others (or the greatest number of others) depend, i.e., the fundamental characteristic is the essential distinguishing characteristic of the existents involved, and the proper defining characteristic of the concept.

Metaphysically, a fundamental characteristic is that distinctive characteristic which makes the greatest number of others possible; epistemologically, it is the one that explains the greatest number of others.” (Ayn Rand, Introduction to Objectivist Epistemology, 2nd Ed., Chapter 5, “Definitions”. New York:Meridian (1990).)

For instance, in the case of the chimpanzee, we know that it is a living organism that must obtain the fuel necessary for its continued existence. It must gather food and other resources. It will seek out females to reproduce with because all living organisms are capable of reproducing themselves, and, with the possible exception of humans, are driven by inexorable mating cycles to do so. Its internal organs are all aimed at sustaining itself. It reacts to its environment and attempts to adapt itself to that environment in a manner that will allow for its continued existence, so it behaves in certain ways. It possesses a consciousness that is, perhaps different from human beings, but a consciousness, nonetheless.

Take away its hair, and the chimpanzee is still a living organism, albeit one that is in a diseased state, so it might not be quite as successful at living. To the extent that human beings interact with a chimpanzee without hair, they will still do so in largely the same way. Hair, as far as human beings are concerned, is not an essential feature of the chimp. But, this is only as far as a human being are concerned. Outside of the way human beings organize certain entities that they perceive in their minds in order to serve human purposes, every entity is unique. No two chimpanzees are the same. The concept of “similarity” serves human needs.

What are some of the “principles of ‘fundamentality’” that human beings adopt in order to serve their purposes? Probably the most important one is the principle of causality. We try to find aspects of reality that we can use to bring about certain results. This is important because reason is our means of survival. So, for instance, we find that certain types of molds kill bacteria. A certain type of mold is the “cause” of bacteria death. We then extract the substance from that mold that leads to the death of certain types of bacteria, and make antibiotics. This means that when we form concepts we look for characteristics that are the “cause” of other characteristics of the thing. The more characteristics of a thing that a particular characteristic(s) causes, the more likely it is to be considered “fundamental”.

This isn’t always an easy task, since we may have incomplete knowledge, but this is what we are doing when we try to find “essential features” of a thing -and finding those essential features is necessary for successful living by human beings. The fact that the concept of essential features is necessary for living life means that there is a “right” and a “wrong” -that some ideas held by human beings are “true” and others are “false”. If one person believes that penicillin kills bacteria while another believes that voodoo incantations will cure disease, then the former is right and the later is wrong. If you want to live, then it’s not all just a matter of arbitrary definitions based on “accidental qualities”.

In the case of a chimpanzee, the fact that he has hair is not considered a fundamental feature. Other mammals have hair, and it doesn’t explain most of the chimp’s behavior patterns or the overall structure of his body. He also is still capable of reproduction with other chimpanzees, which is a strong indicator that an animal is the same species as another animal -although not always a definite indicator. (Wolves and coyotes can interbreed.) Why is interbreeding such a strong indicator? Because two animals breeding and giving rise to offspring tends to be very important to human beings in terms of farming. Agriculture, at least since the Neolithic period, is important to mankind because livestock for food and other purposes is important to human survival.

Essential features are neither “out there”, as Plato/Aristotle would say, nor “arbitrary creations”, as Hobbes would have to say. They are aspects of realty perceived and organized by a certain type of organism, a human being, who needs them to serve a certain purpose, which is living.

The legacy of Hobbes and of the Enlightenment is one in which tradition and authority is questioned. Hobbes just didn’t go far enough when he accepted, without criticism, the idea of “accidental qualities”, because the concept of “accident” does not apply to those aspects of reality that exist apart from human choice. (The “metaphysical”.) Only the metaphysical should be accepted, while all human choices and institutions should be judged, and, if necessary, reformed, if one wants to live.

Published by


I am Dean Cook. I currently live in Dallas Texas.