In the brief introduction to concepts I explained that a concept is a complex consisting of two components, a word and a definition, and that its only function is to identify something which is isolated or indicated by the definition. What a concept identifies are existents, and existents can be anything: entities, events, qualities, relationships, or other concepts; concrete or abstract.

Our simplest, and earliest, concepts identify existents we can directly perceive, things we see, hear, smell, taste, and feel both externally and internally. Such existents include objects, events, qualities, relationships, and internal "feelings."

Earliest concepts are formed almost without effort. The child's mind is very alert and nearly insatiable and almost every association is quickly and easily remembered. A child probably begins to form concepts before it has associated words he has heard with the things in his field of perception.

[Note: Though debated, one piece of evidence for this is called twin language. A child's earliest gurglings and babblings are likely associated with things it perceives as a kind of proto-conceptual language.]

A Word about Words

As stated earlier, "it is words that provide the part of a concept we are conscious of," but also that, it is not spoken or written words, but "words as we think them." This requires some explanation.

A common, but mistaken, notion about concepts supposes a concept is like a little fuzzy picture, or incomplete "abstract" image in the mind of what a concept means. A concept of a horse might be a "little picture" of a white horse one "sees" in their mind. In everyone's experience, some concepts, are accompanied by an image recalled from memory. A boy thinking "apple" might picture a bright red apple, but the concept "apple" can be thought with no attendant image and has identically the same meaning. Most concepts are not accompanied by any image. What "picture" would accompany the concept "important" and exactly what does "mistake" look like?

How, then, do we "think" a word? We can be directly conscious of a word we hear or read (see), but what are we conscious of when we merely "think" it?

When we first learn to read, we read aloud, saying each word as we read them, but when we've learned how to read well enough, we begin to read silently. When we read aloud, we recognize each word, then say each word; but notice, to say the word aloud, two things must occur: we must first have the word in our consciousness and then must choose to say it. When reading, the word is in our consciousness as an image of the word we are looking at, but it is also in our consciousness as something we may choose to do, that is, to say the word aloud. We learn to read silently when we discover that we need not say the words we are conscious of to understand their meaning, and can choose not to say them, but only to "see them in our mind" as we read them. The "seeing them in our mind" is one way we "think a word." It is not the primary way however.

Most of the words we have learned, until we learn to read, are words we've heard and learned the meaning of from others. When someone "speaks" a word, our "hearing it in our mind" is another way of thinking a word. This also is not the primary way we "think a word", however, though it is closer to it.

The primary means of thinking words (or anything else) is related to the primary purpose of language itself. Reading (and writing) and listening (and speaking) language is communication—the primary purpose of language, however, is not communication. The primary purpose of language is to make it possible for humans to have knowledge and to think. We must know something before we can communicate it, and we must think it before we can know it.

Thinking, like reading, can be done aloud. It is a common experience called talking to one's self, often misinterpreted as a kind of mental problem, but is exactly what thinking is, when the talk is reasoning, except that, for adults, like reading, it is usually done silently.

Both reading silently and "talking to one's self" (thinking) silently have to be learned, however, because it is natural to simply speak each word one is conscious of, and to read or think silently requires the conscious choice not to speak the words aloud. Our consciousness of words we would say aloud, if we did not choose not to, is experienced as the "sense of saying the word," even when we choose not to say it aloud.

Exactly what that sense is, as experienced by any individual is not objectively describable, because it is a non-demonstrable conscious (subjective) experience. It is, however, the same experience we have when we actually speak words aloud—it is the experience of choosing to say the word, making the sound and moving the lips and tongue to form it and hearing it as we speak it—but the experience is only in consciousness as if we said it aloud. It is that "sense" which for most people is the primary way of thinking a word.

Any Word At All

Though concepts are not "fuzzy little pictures" of things, the fact that some concepts are accompanied by some kind of image, like the little boy picturing an apple when thinking about apples, is significant. The "picturing" part of what is going on in the mind is not thinking, but "imagination." Imagination is nothing more than perceptual "data" recalled from memory, another subject to be dealt with at length elsewhere. The significance to how we think words, however we think them, is that what we are directly conscious of is perceptual "data" recalled from memory which is perceived just as if it were a direct perception. It is not, however, a percept of what a concept means (not a picture of a referent) that is recalled from memory, but of a word, most often as it is spoken, the sound of it, the lips and tongue moving, for example, which are all perceptual data that is stored in memory.

While the, "sense of speaking a word," is the primary way we think words, it really does not matter which way we think them, because "hearing them in our head," or "seeing them in our mind," all accomplish the same thing—they all provide the perceptual part of a concept, our means of being conscious of concepts.

The reason it does not matter how we think a word is because the word we think is only the mental representation of a metaphysical word, spoken or written, and it is not the word itself our consciousness of it identifies, but whatever the concept it is the symbol for means, that is, its units or referents.

It should be pointed out that just being conscious of a word is not by itself a concept. It is the mental conjoining of a word, as we think it, with a concept's definition; only then does the word we are thinking act as the conscious identifier of something.

Baby's First Words

Whether babies form their own very rudimentary language, or not, we know that baby's' earliest words, which we recognize as words, are similar to (and are obviously attempts to mimic) our own. Babies obviously learn some words from observation alone, but most of them are taught. "Where's Tina's nose?" we say while touching Tina's nose. "Where's Tina's ear?" touching Tina's ear. "Kitty!" we say, guiding Tina's hand to touch the family cat.

When, later, Tina says, "kitty!" upon seeing the family cat, we conclude she has learned the meaning of the word "kitty." Has Tina now a concept "kitty" for a cat?

If the components of a concept are a word and a definition, what is the definition of "kitty" that Tina understands?" It is obvious Tina would understand nothing about animals in general, or the meaning of felix domesticus. "Kitty," to Tina is the thing that looks like the family cat.

A "definition" only has to indicate or isolate that which a word means, that is, what it identifies, from all other things. At what point Tina goes from simply repeating the word "kitty" when she sees the family cat to making the connection that it is "kitty" we do not know, but it is that connection that changes the word "kitty" from a mere word, a sound she can repeat, into a spoken symbol for the concept "kitty."

[Note: Tina does not have to do anything, mentally, to "isolate" Kitty from all other things. Tina recognizes Kitty because Kitty is already isolated from all other things by its its own attributes, both as a cat, as well as the particular cat that belongs to Tina's family. The fact that it is a thing's own attributes that differentiates it from all other things is an ontological fact not learned until much later, if at all.] At first, "kitty" is a particular concept, the identification of a single entity, the family cat. There is a sense in which even particular concepts have a universal aspect, however. If the neighbor's cat comes into Tina's view, if it is similar enough to her own family's cat, she will probably use "kitty" to identify it. Though Tina has not yet learned the concepts of similarity or multiplicity, her concept "kitty" means, "the kind of thing that looks like that," even though she does not know there is more than one of "that kind of thing." For Tina, the same cat on different occasions, or different cats (if similar enough) are the same thing.

It will not be until Tina happens to see two cats, perhaps her family cat and the neighbor's, at the same time that she might first conclude that "kitty" identifies more than one thing. It will be on such an occasion that Tina will form her first "universal" concept.

Two kinds of Concepts

A universal concept identifies things, not as particular individual things, but as members of a class or category of things. It is the difference between Tina's "kitty" identifying the family cat and her later more sophisticated use of the word "kitty" to mean "one of those kinds of things." Most of our concepts are universal.

The concept "dog" for example, means any dog there has ever been, is, or will be, real or imaginary. There is a difference, however, in a concept like "dog" and a concept like, "Athenian," meaning a citizen of Athens. The difference is something that has been a bane to philosophy throughout its history called "essence."

"Athenian," like, "dog," refers to any Athenian there has ever been, is, or will be, real or imaginary, but a dog is a dog because that is it's nature; an Athenian is not an Athenian because it is his nature, but because Athens is where he lives. He would have the same nature (human) if he lived elsewhere.

The reason a dog is a dog, rather than something else, is inherent in the dog itself; it is the kind of being it is; the reason an Athenian is an Athenian is not inherent in Athenians, they would be the same kind of being if Londoners or Parisians. Philosophers call what is inherent in dogs that makes them dogs their essence. The problem for philosophy has been to explain exactly what essence is. Most of the explanations have been disasters that have plagued philosophy with errors that make a rational epistemology impossible.

Another View of Concepts

There is one philosopher in history who came closest to correctly identifying what the essence of a thing really is. Though the explanation is mistaken, the approach to that explanation is correct. That approach, as well as the correct explanation of essence, requires another look at exactly what a concept does.

The only function of a concept is to identify the existents that it is the concept for.

[Note: The meaning of a concept, which are the actual existents it identifies are also called a concept's referents, units, or particulars.]

If the concept is a particular concept, the identification is accomplished by any definition that succeeds in isolating the particular existent from all others. The technical term for that isolation is differentiation; that is, it identifies what makes the existent different from all others. If the concept is a universal concept, it must not only identify what makes those existents different from all other existents, but must also identify what makes those existents members of the same class or category of existents, that is, what is the same about them.

For universal concepts like Athenian, cook, or trinket, the sameness is something external to the existents identified by the concepts and is determined by things such as where one lives, what one does for work, or what something is used for. I identify those kinds of universal concepts as extrinsic concepts. For universal concepts of things that are members of the same category because of something inherent in the existents themselves, like dog, planet, time, or history, it is their very nature that is the same. I identify those kinds of concepts as intrinsic concepts.

Kinds of Things and Essence

What makes things the same kind of things? More importantly, what makes anything the kind of thing it is? The answer to the first question is their essence; everything with the same kind of essence is the same kind of thing. It is the answer to the second question that is the explanation of what essence is. The answer to that question, is epistemological for extrinsic concepts, but metaphysical for intrinsic concepts That difference is one of the most important concepts of epistemology.

For intrinsic concepts, all of metaphysics, especially ontology, bears on the explanation of what essence is. This explanation will briefly touch on the basics of that explanation. Two appendices are included with this epistemology, one explicates the more important concepts from ontology, the other addresses the nature of qualities; both are important to this explanation.

The identity of an existent is determined by its qualities. By "determined" is not meant "caused" but "described." Listing all of a thing's qualities (attributes, characteristics and properties) is one way to identify a thing. It is not the way we do it, however. How we do it will be fully described in the discussion of definitions.

Essence and Qualities

Every existent has two kinds of qualities: necessary and possible.

Necessary qualities are all those qualities of an existent that it must have to be the kind of existent it is, and without which it would not be that kind of existent.

Possible qualities are all the qualities an existent may have, but will be the same kind of existent whether it has any of those qualities or not.

[Note: Necessary qualities also exclude any qualities that would make an existent a different kind of thing.]

A dog is a physical entity, a living organism, an animal, a mammal, and a canine. Physical, living, animal, mammal, and canine or all necessary attributes of a dog. If something had all these attributes except one, it would not be a dog. A dog can have short hair, long hair, a tail, no tail, be very big, or very small. Hair length, tails, and any particular size are all possible attributes of a dog, but none are necessary; a dog will be a dog with or without them.

From ontology we learn the identity of every existent is determined by three necessary conditions: 1. it must have some qualities, 2. it must be different in some way from all other existents; therefore, it must have some quality or qualities that are different from those of all other existents, and 3. every existent has some relationship to all other existents; therefore, it must have some quality or qualities it shares with all other existents.

Obviously it is an existent's necessary qualities that determine the kind of existent it is and equally obvious that every existent with the same necessary qualities is the same kind of thing.

The essence of a thing, therefore, consists of all its necessary qualities. A dog is a dog because it shares with all other dogs the same necessary qualities.

For there to be more than one of any kind of thing, everything that exists must have some quality or qualities that are different from all other existents.

The difference in existents of the same kind must be differences in possible qualities.

Every dog has some possible quality or qualities that are different from the possible qualities of every other dog. No two dogs can have exactly all the same possible qualities. (The differences can be pronounced or very slight.)

The essence of any existent is all the necessary qualities it shares with all existents of the same kind, that is, all those identified by the same concept. Every unit or referent of that concept will have some different possible quality or qualities from all other units of that concept.

"Particulars" of Universal Concepts

A particular of a universal concept is also called a referent or unit of a concept.

The necessary qualities of a particular individual existent are all the qualities it has at any moment. The identity of every particular thing, then, is all the necessary qualities it shares with all other existents identified by the same universal concept, and all possible qualities it has at any moment.

The possible qualities of any particular individual existent, as an individual, are those that can change over time, or have at some times and not at others. The necessary qualities of a particular individual existent are those that cannot change without that existent becoming a different kind of existent. For any particular individual existent, at least one of its necessary qualities, as that particular, must be a possible quality of all other existents identified by the same concept, and it must be different from the possible qualities of all other units of that concept.

All of a particular individual existent's necessary qualities are its essence as an individual.

For all intrinsic concepts, the essence is metaphysical, and if a concept of physical existents, ontological.

For all extrinsic concepts, the essence is epistemological (based on what is known about their function, use, or purpose). If the units of an extrinsic concept are material, the units themselves have intrinsic essences, but as units of an extrinsic concept, the units intrinsic essences, that is, their necessary material qualities, are only possible qualities of the extrinsic concept, not necessary ones.

For example, I own many pairs of chop sticks. They are all units or referents of the concept, "chop sticks." Their essence as chop sticks is, "two straight sticks used as implements for eating." The necessary qualities are, "sticks" that are "straight" with the exact quantity "two" with the function of being used "to eat with." I'll call this essence, "chop-stickness."

The essence,"chop-stickness," is strictly epistemological. While sticks are physical entities, and straight is a physical attribute and those qualities are necessary to chop sticks, "chop-stickness" is not inherent in chop sticks, because straight sticks can have many other functions (cue sticks or drum sticks, for example) and those qualities are attributes of many other kinds of existents. Notice it is the function, "to eat with," combined with the physical attributes (straight stick) that differentiates chop-sticks from all other things, including eating implements of other shapes.

I have chop sticks that are made of wood, others made of bamboo, and still others made of plastic. Wood, bamboo, and plastic are all intrinsic concepts; the essences of wood, bamboo, and plastic are metaphysical, the necessary attributes of these substances are material. As any of these essences is instantiated in chop-sticks, they are only possible qualities, however, because chop sticks can be made from many different substances and still be chop sticks.

[Note: Those with a philosophical background may notice a resemblance between necessary and possible qualities and the classical essential and accidental qualities. The meaning of essential and accidental is somewhat different, however, the concept "essential" having its origin in Platonic forms. I retained the word "essence" because it is easy to define, and I do not believe it will be confused with that word as used in other contexts. Other possible choices were quiddity, hypostasis, and haecceity, but all of these pertain to the essence of individual particulars, not classes or categories of existents.]

[Note: As stated before, I have no intention of refuting the mistaken philosophical view of other philosophers. However, I mentioned that another philosopher came very close to correctly describing the nature of essence, and need to say something briefly about that. Though reluctant to do so, because this is not about personalities, I've been advised to provide the name of that philosopher. The philosopher was Ayn Rand.

Ayn Rand did not use the word essence, nevertheless, that is what is being described. I'll summarize that description:

Measurement-Omission Theory of Concepts

The units or referents of a concept are the same kind of existents because they are similar. Similar means partly the same and partly different. What is different about existents of the same kind is more or less obvious, the difficulty is determining what is the same about them. Rand's explanation is that two or more things are similar when their qualities (or attributes) are the same; what is different about units of the same concept is the magnitude or "measurement" of those shared qualities. This is called "measurement omission."

This explanation differs from the correct one at two points. First, it makes no distinction between intrinsic and extrinsic concepts. The second difference is that it accounts for only one kind of possible qualities, magnitude.

The first difference is important because most of our concepts are extrinsic. The only intrinsic concepts are those of physical substances, naturally occurring physical entities, organisms, naturally occurring physical events, relationships, and attributes, and all concepts abstracted from these, such as attributes of life, values, scientific principles and similar concepts. All other concepts are extrinsic, including all man-made physical existents, activities, services. Almost all extrinsic concepts are defined by their purpose, function, or use of the units subsumed by the concept, none of which have magnitude as an attribute.

The second difference is interesting, because, for a small subset of intrinsic concepts, Rand's explanation is correct. The "measurement-omission" explanation does work for that subset of existents which are strictly defined by their geometric nature or quantitative attributes. A triangle is a triangle because it has three sides, and every triangle has those same qualities (attributes) and the difference between triangles is strictly the difference in the lengths of their sides, and of course the resulting difference in their angles. It does not work for any other kind of existent, however.

Consider Rand's own example which is intended to describe the formation of the concept "table."

According to the, "measurement-omission" theory of essence, the formation of the concept table begins with the observation that tables are differentiated from other things by their distinctive shape: a flat surface with supports, for example. The concept table leaves out the measurement of geometric characteristic of a table, but retains those geometric characteristics; for example: the concept leaves out the shape of the surface (round, square, octagonal), the number of legs, height, and weight, but retains the fact it must be some shape, have a leg or legs, be some height, and weigh something.

What actually distinguishes a table from all other things is not its shape, but its function. The possible number of different shapes a table can be is endless, and for almost all those shapes, there are other kinds of furniture and objects with exactly the same shape. In some parts of the world there are tables that look more like beds, and beds that look more like tables—if shape alone were what distinguished tables from beds—they could not be distinguished. A table and a bed might have exactly the same shape (and measurements); what distinguishes them is what they are used for.

This mistake is partly the result of the failure to distinguish between intrinsic and extrinsic concepts. Since "table" is an extrinsic concept, as are all concepts for man-made things, its essence will not be comprised of measurable necessary qualities, though it may have measurable possible qualities.

[Note: An automobile is an extrinsic concept, determined primarily by an automobiles use. But an automobile is a real metaphysical object. That is true, and part of the essence of an automobile will be that it is a physical object with wheels, but that cannot define an automobile. The defining "essence" is what an automobile is designed and used for.]

There is an essence of every concept, or more exactly, of the units of every concept that describes what they are, and that essence is all their necessary qualities, but only the units of intrinsic concepts have a metaphysical essence; the essence of all other things is epistemological, that is identified conceptually, not from observation.

Some examples of things without measurable necessary qualities

From medicine—

antibiotic, with units: Penicillins, Cephalosporins, Macrolides, Fluoroquinolones, Sulfonamides, Tetracyclines, Aminoglycosides, which obviously have no common measurable attribute. Each antibiotic is also a concept, the referents of which have no common measurable attribute. Someone suggested that all have measurable dosages, which is true, because dosage is a possible attribute of all drugs; but it is simply a quantity. Certainly penicillin is not "a drug with some quality with the specific measure (dosage) of that quality left out. The necessary qualities of antibiotics are their specific purpose and function, which is not measurable.

hormones, with units: testosterone, estrogens, thyroxine, epinephrine (adrenalin), insulin, norepinephrine, cortisol, corticosterone, aldosterone, corticotropin (adrenocorticotropin, ACTH), growth hormone (GH or somatotropin), thyrotropin, and thymosin. What would the common attribute of these things be, the measurement of which is left out?

General concepts—

mind or attributes and functions of the mind, such as reason, concept, percept, memory, imagination.

philosophy and its branches, such as metaphysics, ethics, politics, aesthetics, logic.

language or its parts or structures such as verbs, nouns, pronouns, prepositions, adjectives, adverbs, conjunctions, declension, conjugation, subject, predicate, participle, gerund, infinitive.

adjective or particular adjectives, such as mysterious, pregnant, alive, dead, true, and false?

My favorites: heliocentrism and vegetarianism. Can anyone deny these are concepts? What measureable attributes do they have?

Rand was very close. The units or referents of a concept all share the same essence, that is, the same necessary qualities, with their "differentiating possible qualities left out." Rand's shortcoming was that she only identified one kind of differentiating possible qualities, magnitude (measurable attributes), which works only for one small subset of existents.]

—Reginald Firehammer (11/01/04)


  1. A concept is a complex consisting of two components, a word and a definition, and its only function is to identify something which is isolated or indicated by the definition.

  2. The existents a concept identifies can be anything: entities, events, qualities, relationships, or other concepts; concrete or abstract.

  3. A word is the part of a concept we are directly conscious of, that is, it is the perceptual part of a concept.

  4. It is a word as we think it that is part of a concept (not the word we see, write, hear, or say).

  5. We can think a word by "seeing," or "hearing" it in the imagination, or as the "sense of saying it," which is the most common way.

  6. Babies first form concepts by making the connection that a thing is what a word identifies.

  7. A Baby's first universal concept is formed when the Baby discovers there is more than one of something previously known only as a particular concept.

  8. There are two kinds of concepts: intrinsic and extrinsic.

  9. The essence of things identified by intrinsic concepts is inherent in the existents and is metaphysical.

  10. The essence of things identified by extrinsic concepts is not inherent in the existents but determined by the existent's purpose, use, function, or relationship to something else; it is something known about the existents and is therefore epistemological.

  11. There are two kinds of qualities (attributes, characteristics and properties): necessary and possible.

  12. Necessary qualities are all those qualities of an existent it must have to be the kind of existent it is, and without which it would not be that kind of existent and excludes those qualities with which it would be a different kind of existent.

  13. The essence of a thing consists of all its necessary qualities.

  14. All the qualities of a single existent, at any particular moment, are necessary qualities; it's identity at that moment includes all those qualities.

  15. For the duration of an existent, the possible qualities of a single existent are all those qualities that can change or be qualities at some times and not at others.

  16. For the duration of an existent, the necessary qualities of a single existent are all its qualities that do not change over time, and are that existents essence.

  17. The necessary qualities of a single existent are identical to the necessary qualities of all the existent of the same category identified by the same universal concept, plus at least one more necessary quality that is a possible quality to the universal concept and different from the possible qualities of all other referents of that universal concept.

  18. All the units or referents of universal concepts share the same necessary qualities and therefore have the same essence.

  19. All the units or referents of universal concepts have some different possible qualities from all other units of that concept.