Person outdoors, holding an open book

Epistle 2. Posted on 2019-01-22. Edited on 2019-05-06.

One of the most important skills in introspection and philosophical counseling is the skill of developing and refining definitions of concepts. Whatever the topic of interest, there are important concepts that need to be defined with respect to your experience, with your own definitions. For example, if someone experiences grief, the dictionary definition of grief is (mostly) unimportant. Instead, it is the personal experience and concepts related to a topic that are relevant in introspection. For a grieving person, what does grief mean to them? They grieve a loss, what does loss mean to them? They lost their spouse? What does spouse mean to them, and so on.

The main reason that I have asked you to read this article is that I intend to collaborate with you with respect to developing and refining definitions of concepts that are important to your topic of interest. I strongly believe that embracing this material is good for you throughout your life, and that familiarity with it now will reduce the time required to explore certain concepts and definitions in philosophical counseling.

There are many reasons to learn how to develop and refine your own definitions of your own concepts. This allows you to be clearer about what you mean when you refer to that concept. When this definition is shared, it allows the philosophical counselor to have a better idea of what you mean and imply by the concept. It helps you learn about the concept, represent it more accurately, and prevent some bad judgments. Most importantly, it allows you to be more consistent in your reasoning about important concepts in your life, as well as connections between important concepts. Being skillful with definitions is crucial to developing a reasoned sense of meaning and purpose.

What you should expect is to be amazed and thrilled as you learn about yourself, and I am honored to be your guide. On my end, definitions of concepts are necessary for evaluating propositions, for using logic. Skill in developing and refining definitions is one of the two most important skills in using analytic logic, which is to practice formal reason.

Genus and Differentia

We will focus on a particular kind of definition called the genus and differentia definition. To define anything, you must regard it as belonging to a larger category of things, a genus, and then specify how it is unique among all the members (or species) of that category. In biology, there is a taxonomic structure, such that each species belongs to a genus, and each genus to a family, and so on. Of these taxonomic terms, we only need genus and species.

Aristotle introduced the genus and differentia definition, and the most famous example is the definition of a human as a rational animal. Each human is an animal, and so an animal is regarded as the genus, and the human is a species of that genus. There are many other species of animal, including cats, dogs, and so on. Next, Aristotle reasoned that rationality, the capacity for reason, is what makes a human unique among the species of animals. Rationality is the differentia, it is what defines our species.


Each genus and differentia must also be essential to the defined object. Here, essential means conceptually necessary. If it is conceptually possible that any instance of that category of object does not have that genus or differentia, then the definition is unsuitable. It must be, not merely possible, but necessary.

For example, cynical Cedric attempts to define a human as the animal that has damaged the planet. Let us first drop the past tense so that the definition can apply to any human, including the future. Cedric regards a human as an animal that damages the planet. For this definition to be suitable, every human must damage the planet (because if they don’t, they’re inhuman), and it must be conceptually impossible for a human not to damage the planet. According to his definition, he is declaring that it is impossible for scientist Suzy not to have harmed the planet in any way. Notice, however, that Aristotle’s definition seems to remain suitable; necessarily every human is an animal, and every human is rational (has the capability to reason).

This brings up the difference between everything in experience being a certain way, and it being conceptually impossible for something not to be that way. Newby Nathan has never before seen a marble, and is shown an urn with three blue marbles inside. Although he has never seen a non-blue marble, this does not imply that all future marbles will also be blue. Newby Nathan considers that there is nothing essential about a marble having a specific color, that it is conceptually possible for a future marble to be green. However, his definition of a marble most likely makes it essential that a marble is round.

Specific Genera

A modern critic of Aristotle’s definition of a human might quip that a more specific genus is a primate, and that the differentia is that we have the largest proportion of cerebral cortex to the rest of our brain. The critic may present the alternative definition that a human is a primate with a cerebral cortex in the largest proportion. Better definitions have more specific genera (genera is the plural of genus).

Both of these definitions are correct for each person. One is better than the other because it is more specific, but neither is erroneous. Usually but not always, a more specific genus results in more accuracy, but in this case, both definitions may have the same accuracy, because the cerebral cortex is the source of rationality.

Most Explanatory Differentia

A definition may have multiple differentia that all appear suitable. The best differentia is the one that explains the most of the essence of the concept, meaning the most qualities that are conceptually necessary.

As an example, a biologist once defined a human as the animal that is in heat throughout the year. Suppose this biologist is considering which is the better differentia: rationality or lack of a mating season. Rationality explains more of the qualities that are essential to humanity, such as the capabilities to author books and compose music.


A definition needs to be consistent with other concepts and definitions, as well as with the object defined. A human should not be defined as a type of piano, obviously.


A goal in developing any definition is that it is accurate with respect to the object defined. A human should not be defined so that it includes a non-human as a human, or such that it excludes a category of human such as Californians or clerks. A definition of a human should distinguish accurately a human from a non-human, for instance.

Even though accuracy is a goal, each person’s experience of the world differs, and therefore concepts differ between people. Although it is desirable to arrive at a definition that everyone would agree with, there may be no such thing as one, correct definition for an object; each of us has a unique context.


So far, every concept has been a noun. But, we have concepts for adjectives such as tall, adverbs such as quickly, and verbs such as walks. A definition can be developed for any concept, regardless of its part of speech, though a conversion is required. To convert a non-noun to a noun, consider adding a generic -ness suffix. The result is a common noun, as opposed to a proper noun. A common noun refers to a member of a category of objects, or to the category itself, whereas a proper noun refers to one, particular object.

For example, the concept of tall becomes the concept of a tallness, quickly becomes a quickness, and walks becomes a walkness, which is more recognizable as a walker. It is awkward to attempt to define the concept of walk without respect to any objects that walk. It is fruitless to attempt to conceive of the color red, absent any red object, and so on. By converting walks to a walker, we can now refer to a category of walking objects, and any walking object is a walker, just as tallness refers to a category of tall objects.

The main advantage to requiring nouns is that either objects or categories of objects must be referenced. The concept of freedom is defined with respect to free objects, happiness with respect to happy objects, love with respect to lovers, and life with respect to the living.

From Socrates to You

Socrates asked people about concepts that they were confident that they knew. For example, he would ask someone if they know what justice is, and they would proclaim they know for sure. Socrates asked questions in order to explore the development of a definition. He kept refuting the current and proposed definition by demonstrating inaccuracies, and his subject responded repeatedly by proposing a refined definition. The point is that, by attempting to develop or refine a definition of something, even something you think you know very well and are very familiar with, most people quickly realize their first few attempts at defining it are poor, and that the subject was very poorly understood.

If all of this seems too simple, some exceptions may be interesting. For example, consider the field of biology, which means the study of life, and that, surprisingly, this field does not endorse any definition of life. Isn’t that curious? After all, how can you study something without an operational definition of what it is? The reason this academic field does not endorse any definition, I conjecture, is to avoid political and social implications. That seems rather sad for an academic field to be stifled so easily.

The field of statistics does a better job of defining probability, but a central problem is called the problem of induction, in which inductive inference (which includes all probability statements) cannot be justified, except with other inductions. Consequently, its justification is circular. Why is the field of statistics regarded as legitimate, and as part of science? It is mysterious, when you examine it closely. The reason is because, although induction is commonly called the scandal of science, induction has been extremely successful. Nonetheless, induction is not justifiable. Bertrand Russell (1872–1970) provided an example in which a chicken is fed by a farmer every day, until finally its neck is wrung. Each day, the chicken expects food from the farmer, but on its last day, that expectation is proven to lack justification. The scientific method is largely due to the deductive logic of Karl Popper (1902–1994), who claimed adamantly that induction has no place in science. This certainly calls into question many studies in journal articles in everything from economics to medicine to psychology.

Mathematics has defined itself with set theory, which has the odd assumption that abstract objects are actual, physical objects. If that assumption is removed and the basis of mathematics became consistent with a reasonable sense of reality, set theory would have to be replaced, as I understand it. Some alternative systems have been proposed, which are based on relations between parts and wholes, rather than between sets and members of sets. Even mathematics has issues with definitions, though this academic field probably has the fewest number of problems.

Good luck looking for a uniformly accepted definition of the field of philosophy, which I regard as the pursuit of good judgment. If it were up to me, I would define it as the department of logic, and strive to demonstrate that analytic logic is the basis upon which every other academic field relies.

The point is not to analyze our academic fields, but to demonstrate that a habit of developing definitions is worthwhile, and is certainly not a fruitless exercise.

I encourage you to begin the lifelong consideration of the concepts of everything important to you in terms of definitions. How do you define friendship, happiness, humanity, life, love, meaning, purpose, yourself, wisdom, value, and so on.

But before you delve into these concepts, please develop a definition of something I am sure you are confident that you know: please define a table. I look forward to hearing your definition, next we meet.

Vale (pronounced WAH-lay is Latin for Farewell),

Ron Hall

Ron Hall

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