Definitions and Conceptual Analysis

A central aim of this e-book is to help you learn to think clearly and carefully. In order to clarify our thinking, it is often helpful to analyze (dissect, study, and examine) the concepts we employ. In fact, some of the most foundational questions in philosophy are questions about concepts. What is truth? What is knowledge? What is beauty, goodness, justice, or virtue? What is a person? What does it mean to exist? And so on.

Such questions are foundational, in the sense that our thinking about other philosophical issues depends on our prior understanding of these important concepts. For example, before we can address the question of how to obtain knowledge, we need to understand what knowledge is. Similarly, in order to pursue goodness, justice, and virtue, we need to know what we’re pursuing. And when we consider how it is possible to have a personal relationship with God, we must have some grasp of what a person is. We need to understand what we’re talking about.

One might be tempted to address those conceptual questions by consulting a dictionary. What is knowledge? Just look up the word ‘knowledge’ in Merriam-Webster’s or the Oxford English Dictionary, and you’ll have an easy answer! Unfortunately, however, the dictionary definition of a word usually doesn’t produce the depth of understanding we seek in philosophical inquiry.

There are various kinds of definitions, which serve different purposes. In what follows, we’ll distinguish several types of definitions and consider their roles in philosophy. We’ll also learn some basic strategies for analyzing concepts and constructing philosophically useful definitions.

Four Kinds of Definitions

There are numerous ways of classifying definitions. One helpful classification distinguishes types of definitions by their different aims or purposes. Here are several of the most common kinds of definitions employed by philosophers:

The kind of definition found in a dictionary is called a lexical definition. Its purpose is to explain the accepted meaning(s) of a word or phrase as it is used by a linguistic community. For example, the Oxford English Dictionary explains the meanings of words as used by English speakers in general, while the Oxford Dictionary of Philosophy explains the meanings of terminology and technical jargon employed in the community of professional philosophers. Lexical definitions may be correct or incorrect, depending on whether they accurately represent accepted meanings, and the correct definitions may change over time as linguistic conventions evolve.
Many words and phrases have more than one lexical definition. For example, the word ‘proof’ may refer to compelling evidence for a claim, or it may refer to a formal derivation within a system of deductive logic. To avoid ambiguity, philosophers may use a precising definition, specifying precisely which meaning is intended in a specific context. Precising definitions also can be used to restrict the meaning of a vague term. For instance, the word ‘youth’ is vague: there is no precise age at which youth ends. When addressing philosophical issues involving vague concepts (e.g., when discussing how the moral responsibilities of youths differ from those of adults), philosophers sometimes find it useful to reduce the vagueness with precising definitions, for instance by defining ‘youth’ to mean a developmentally average person under a certain age.
Occasionally, philosophers devise novel concepts for which no words have been invented. In such cases, a new word or phrase may be introduced and defined with a stipulative definition, which stipulates the meaning of the freshly-minted terminology. Much of the technical jargon in philosophy, as well as in other academic disciplines, originated in this way. Terminology introduced by stipulative definition may eventually gain broad acceptance, in which case the stipulative definition becomes a lexical definition. The term ‘altruism,’ for example, was coined in 1853 by French philosopher Auguste Comte, whose stipulative definition for the word has become the lexical definition widely employed today, even outside the philosophical community.

Lexical, precising, and stipulative definitions all have important purposes. The purpose of a lexical definition is to explain the accepted meaning of a word, the purpose of a precising definition is to reduce ambiguity or vagueness, and the purpose of a stipulative definition is to assign a meaning to a newly-coined term. However, none of those three kinds of definitions is exactly what we’re looking for when we ask foundational philosophical questions like what is knowledge or what is virtue. Stipulative definitions won’t help to answer those questions, obviously, since knowledge and virtue aren’t novel concepts. Precising definitions only specify which of various possible meanings is intended in a particular context, so they won’t help to deepen our understanding of the concepts in question. Lexical definitions just explain the conventionally-accepted meanings, which are often superficial. This may be helpful when we encounter unfamiliar terminology, but lexical definitions don’t shed much light on concepts that are already familiar to us.

If we want to gain a deeper understanding of concepts like knowledge, beauty, and goodness, simply looking up their definitions in a dictionary won’t help much. As competent speakers of English, we already understand how these words are used in ordinary language. That’s why dictionaries usually don’t provide interesting answers to profound philosophical questions. We already understand, at a superficial level, what it means to say that someone “knows” something, and what it means to call something “beautiful” or “good.” We understand how to use or apply these concepts in a wide range of cases. At least, we understand how to apply them in the easy cases, when there is no dispute. For example, almost everyone agrees we know uncontroversial things like President Lincoln was assassinated and the moon is closer to Earth than the sun is.

However, the superficiality of our understanding becomes apparent when we consider controversial questions about beauty, knowledge, virtue, and other such concepts. Are Pollock’s abstract paintings beautiful, and if so, what determines this fact? Is beauty objective, or is it all in the eye of the beholder? Is assertiveness a virtue, and if so, what makes it virtuous? Do Christians really know God exists, or do we merely believe it? What conditions must be met in order for this belief to count as knowledge? The exact requirements for knowledge, beauty, and virtue (etc.) are far from obvious. When we ask philosophical questions like what is knowledge or what is beauty, we are probing the essence of these concepts, trying to develop a deeper understanding that will enable us to adjudicate the controversial cases.

Sometimes, the deeper understanding we seek can be provided in the form of a fourth kind of definition, called a theoretical definition:

A theoretical definition is a definition introduced as a theory or as part of a theory or framework of interrelated concepts. The purpose of a theoretical definition is to improve our understanding of whatever subject the theory addresses. Some theoretical definitions are also stipulative definitions in the sense defined above: they introduce new terminology for novel concepts. For example, the 19^th-century physicist Rudolf Clausius coined the term ‘entropy’ for a quantity introduced as part of his newly-developed theory of thermodynamics. However, many theoretical definitions are intended to replace or improve existing lexical definitions. The latter sort of theoretical definition can, and often does, deepen our understanding of a familiar concept.

Theoretical definitions are especially common in the sciences, and the following example from physics nicely illustrates how theoretical definitions can improve our understanding of a familiar concept and even replace inadequate lexical definitions.

Prior to the publication of Isaac Newton’s Principia in 1687, heavy objects were thought to possess an inherent tendency to move toward the center of the earth, and the word ‘gravity’ was used in reference to that supposed tendency. However, Newton’s theory of universal gravitation redefined ‘gravity’ to mean an attractive force between any two objects with mass. Newton’s theory had many advantages over the previous idea: not only did it explain why heavy objects fall toward the center of the earth, it also explained numerous other phenomena—including the orbital motions of planets around the sun, the moon’s orbit around the earth, and why the ocean’s tides are correlated with the moon’s orbit. So, Newton’s theory of universal gravitation was quickly accepted, and his definition of gravity soon became the lexical definition.

Another shift in the meaning of ‘gravity’ occurred a few centuries later, with Albert Einstein’s theory of general relativity. Einstein redefined gravity yet again, not as a force but as an effect of spacetime curvature. Moreover, general relativity has important advantages over Newton’s theory of gravity: it explains everything that Newton’s theory had explained, and it also explains numerous additional phenomena—including, for example, the surprising fact that gravity affects the path of light. Though it took a few decades for physicists to test the predictions of general relativity, Einstein’s theory prevailed, and his theoretical definition of gravity eventually superseded Newton’s as the accepted lexical definition, at least in the physics community.

Similar success stories have occurred in philosophy, where a new theory or conceptual framework sometimes offers advantages over a previous view—advantages such as greater precision and clarity, better agreement with commonsense intuitions, or more fruitful applications. For example, the Bayesian theory of confirmation (which we’ll encounter later, in the chapter on Confirmation Theory) offers many advantages over its predecessors and it also provides useful theoretical definitions of some important philosophical concepts, including the concepts of evidence and confirmation.

In some cases, a theoretical definition itself just is the whole theory. For example, philosophers have developed various theories concerning the meaning of knowledge. Most of these theories attempt to deepen our understanding of knowledge not by situating the concept within a broader theory, but by providing an insightful definition: the definition itself is the theory. We’ll examine one such theory (or theoretical definition) of knowledge shortly.