Locke’s Essay Concerning Human Understanding

John Locke’s An Essay Concerning Human Understanding (1689) is an inquiry into the source and limits of human knowledge, and is an examination of the nature of belief, opinion, and faith. Locke explains how knowledge is gained from sensation and reflection, how knowledge is distinguished from belief or opinion, and how certainty of knowledge is attained by intuition, reason, and sensation.

Locke also discusses the relationship between knowledge and language, the relation between words and ideas, the causes of the misuse of language, the causes of error in making judgments, the nature of truth, the nature of the reality of knowledge, the role of judgment in deciding upon truth or falsehood, and the boundaries between faith and reason.

Locke’s Essay is divided into four books: Book I: "Of Innate Notions," Book II: "Of Ideas," Book III: "Of Words," and Book IV: "Of Knowledge and Opinion."

Book I is a sustained attack against the doctrine that there are innate ideas in the human mind. Book II presents the theory that all ideas arise from sensation and reflection. Book II argues that ideas may be simple (e.g pleasure and pain) or complex (e.g. modes, substances, or relations), that some ideas may be clear and distinct while other ideas may be obscure and confused, and that ideas may be adequate or inadequate representations of the experiences which produce them. Book III explains that words signify ideas, that words are necessary for communication, that words may be misused when they are misapplied to confused ideas, and that the misuse of words may be a source of error. Book IV asserts that ideas are the source of human knowledge, that ideas determine the nature and extent of human knowledge, and that ideas determine the reality, truth, and certainty of human knowledge.

Locke begins by presenting a number of arguments against the existence of innate ideas. These arguments include the proposition that if there were innate principles of truth in the human mind, then these principles would be universally recognized. But careful examination reveals that there are no such universally recognized principles of truth. Even if there were truths which were universally agreed upon, this fact would not prove that such truths are innate in every human mind.

Another argument against the existence of innate ideas is that if there were innate principles of truth in the human mind, then reason would not be necessary to discover these principles of truth. However, reason is indeed necessary to discover such basic principles of truth.

Another argument against the existence of innate ideas is that if there were innate moral or practical principles in the human mind, then these principles would be universally known and agreed upon. However, there are no such universally agreed-upon moral or practical principles. Reason is necessary to determine the truth of moral or practical principles. Moreover, if there were innate moral or practical principles in the human mind, they could be easily distinguished from other moral or practical principles; but it is impossible to divide moral or practical principles into those which are innate and those which are not innate.

According to Locke, any ideas in the mind are either actual perceptions or are formed from memories of previous perceptions. If there were any innate ideas in the mind, then they would have to be memories of previous perceptions. These perceptions would have to be caused by previous sensation or reflection, but memories of previous perceptions could not be innate if they were produced by previous experience, and thus there are no innate ideas in the mind.

Another argument against the existence of innate ideas is that if there were any innate ideas, then they would be clear and distinct and would be easily distinguishable from other ideas. However, the truth of some ideas is clear and distinct, while the truth of other ideas is more difficult to discover. Truths which are clear and distinct cannot be assumed to be innate, any more than truths which are more difficult to discover can be assumed to be contingent and not necessary.

According to Locke, there are two sources of knowledge: 1) sensation and 2) reflection. The objects of sensation are things external to the mind. The objects of reflection are the internal operations of the mind. Ideas may be simple or complex. Simple ideas may be provided by sensation and reflection. Complex ideas may be provided by variations, combinations, and relations of simple ideas.

Locke explains that some ideas may be provided by a single form of sensation, while other ideas may be provided by more than one form of sensation. Some ideas may be provided by both sensation and reflection. Simple ideas of reflection include perceptions (thoughts) and volitions (acts of will). Locke says that the understanding is the faculty of thinking, while the will is the faculty of volition. Simple ideas of both sensation and reflection include: pleasure, pain, power, existence, and unity.1

Locke also explains that complex ideas include: modes, substances, and relations. Modes may be simple (variations of ideas) or mixed (combinations of ideas). Ideas of substances may represent particular things which are characterized by distinct qualities. Relations may compare ideas with each other.

Simple modes include modes of space, duration, number, motion, sensation, thinking, feeling, and power. Modes of space include: distance, capacity (or volume), figure (or shape), and place (or location). Modes of duration include: finite duration (time), and infinite duration (eternity). Modes of sensation include: taste, touch, smell, vision, and hearing. Modes of thinking include: remembrance, recollection, attention, dreaming, reasoning, judging, willing. Modes of feeling include: love, hatred, desire, joy, sorrow, hope, fear, despair, anger, envy, grief. Modes of power include active power and passive power.

Locke argues that ideas about active and passive power are simple ideas and are the source of our ideas about liberty and necessity. Locke describes liberty as the power to perform, or not to perform, voluntary actions according to the determinations of the mind. Necessity is the lack of power to alter or control a mode of action according to the determinations of the mind. Necessity may take the form of compulsion (involuntary action) or restraint (hindrance of action).

Regarding the question of whether there is freedom of the will, Locke argues that freedom and the will are each a power or ability which may belong to an agent or individual. Freedom belongs to an agent or individual, and not to the will itself, because the will is only a power or ability. The will cannot be described as free or not free, because it is not an agent or individual. Furthermore, the will is not a substance or being.

According to Locke, human beings may have freedom of volition, but they do not have freedom from having volition. They may be free to will, but are not free not to will. Liberty is a power to act, or not to act; but human beings cannot choose whether or not to have the power of volition. They can only choose whether or not their actions will be guided by their own volition.

Volition may be determined by a desire for pleasure or for the avoidance of pain. Happiness may be produced by actions which are good, while misery may be produced by actions which are evil. Good actions may be performed because they produce pleasure, while evil actions may be avoided because they produce pain. Good actions may also be performed because they are seen as good in themselves, while evil actions may be avoided because they are seen as evil in themselves.

Locke defines desire as a state of uneasiness which is produced by a longing for something. The satisfaction of desire produces happiness, while the frustration of desire produces unhappiness. Desire may not direct volition toward every form of good, because every form of good may not be seen as necessary for happiness. Moreover, human beings have the power to delay or suspend satisfaction of their desires, in order to attain an ultimate good. Thus, the desire for happiness may direct volition toward a particular form of action, but the desire for happiness is in turn guided by the faculty of judgment within the understanding.

Complex modes include modes of motion, thinking, and power. Complex ideas may also include ideas of substances and relations. Complex ideas of substances include: 1) ideas of the primary quality of things as discovered by sensation, 2) ideas of the secondary quality of things as discovered by sensation, and 3) ideas about the active and passive powers of change in the primary qualities of things as discovered by sensation. Locke contends that relations may be defined more clearly and distinctly than substances, and maintains that it is generally more difficult to define all the simple ideas which are combined into complex ideas of substances than it is to define all the simple ideas which are combined into complex ideas of relations. Relations are complex ideas which include: relations of cause and effect, relations of time, relations of place and extension, relations of identity and diversity, relations of proportions, relations of law, and relations of morality.

Locke declares that ideas may be described as clear and distinct, or as obscure and confused. Complex ideas may be clear and distinct in one aspect, but may be obscure and confused in another aspect. Ideas may also be described as real or illusory, true or false, adequate or inadequate.

Locke argues that the mind is passive insofar as it receives simple ideas from sensation, and that therefore all simple ideas are real. The mind is active insofar as it combines simple ideas to form complex ideas, and therefore complex ideas may be either real or illusory.

Locke also argues that all simple ideas are adequate, but that complex ideas may be either adequate or inadequate. Complex ideas of modes and relations are adequate, but complex ideas of substances are inadequate. Adequate ideas are those which perfectly represent the archetype to which they refer, while inadequate ideas are those which imperfectly represent the archetype to which they refer.

Abstract ideas may be either simple or complex. Abstract ideas define the nominal essence of things, but do not always define the real essence of things.

According to Locke, ideas are true or false only insofar as they refer to propositions. Sensations cannot be called true or false unless the mind makes some judgments about them, and then truth or falsehood belongs to the actual judgments and not to the sensations themselves. The truth or falsehood of propositions or judgments may reside in: 1) whether they conform to what they are intended to represent, 2) whether they refer to something that really exists, and 3) whether they refer to the real essence of something.

In analyzing the relation between language and knowledge, Locke says that words are signs of ideas. Proper names signify particular things, while general names (or terms) signify a class or category of things. General terms are signs of abstract ideas, which may define the essence of a class or category of things. Each distinct, abstract idea defines the distinct essence of something. The real essence and nominal essence are not the same for any substance which is referred to by a complex idea. Locke argues that the real essence of substances is unknown. However, the real essence and nominal essence are the same for any sensation which is referred to by a simple idea. The names which are given to simple ideas may be either concrete or abstract.

Locke explains that language may be misused or misunderstood when a speaker or writer uses words which do not refer to any clear or distinct ideas. Misuse of language may also occur when a speaker or writer uses words which are inconsistent in their meaning. Misuse or misunderstanding of language may also occur when words which only represent the nominal essence of a substance or quality are assumed to represent the real essence of a substance or quality. Misuse or misunderstanding of language may also occur when it is falsely assumed that the listener and the speaker share the same understanding of the meaning of words.

To prevent the misuse of language, Locke recommends that every speaker or writer use words which refer to clear and distinct ideas. Words which refer to complex ideas should be clearly defined, and names of complex ideas should have commonly accepted and recognized signification. A speaker or writer should not use words which do not have any consistent meaning.

Knowledge, according to Locke, is gained through perception of how ideas agree or disagree. Ideas may agree or disagree in their: 1) identity, or diversity, 2) relation, 3) coexistence, or necessary connection, and 4) real existence (i.e. their reference to something that actually exists).2

Locke defines three degrees of knowledge: 1) intuition, 2) demonstration, and 3) sensation. Intuitive knowledge is an immediate perception of the agreement or disagreement of a group of ideas, without the intervention of any other ideas. Demonstrative knowledge is a perception of the agreement or disagreement of a group of ideas, based on reasoning and on proofs provided by intervening ideas. Sensory knowledge is a perception of the agreement or disagreement of a group of ideas, based on sensory experience of the external objects to which they refer.

Locke says that demonstrative knowledge is based on intuitive knowledge, in that every step in reasoning which produces demonstrative knowledge also provides intuitive certainty.3 Demonstrative knowledge of the agreement or disagreement of any group of ideas is based on an intuitive knowledge of the agreement or disagreement of any intervening ideas. Thus, knowledge may have both intuitive certainty and demonstrative certainty.

Locke also argues that knowledge can extend only as far as our ideas can extend.4 Intuitive knowledge cannot be extended to all ideas, and demonstrative knowledge cannot be extended to all ideas. The agreement or disagreement of all ideas cannot be known by intuition. The agreement or disagreement of all ideas cannot be known by reason. The agreement or disagreement of all ideas cannot be known by sensation. Locke also emphasizes that misuse of language may hinder perception of how ideas agree or disagree and thus may limit knowledge.

Knowledge may become universal if it is attained through perception of the agreement or disagreement of abstract ideas.5 Perception of the agreement or disagreement of abstract ideas may provide universal truths. Truth belongs to propositions insofar as they unify words and ideas which agree with each other, and insofar as they separate words and ideas which disagree with each other.

Locke explains that propositions may be mental or verbal. Verbal truth may belong to propositions which unify words and ideas which agree with each other, but in order to have real truth, propositions must also represent ideas which agree with objective reality. Propositions representing ideas which disagree with reality may have verbal truth, but not real truth. Knowledge is real insofar as it is based on ideas which agree with the objective reality of the world.

According to Locke, human knowledge may be threefold, in that: 1) intuition gives us knowledge of our own existence, 2) demonstration gives us knowledge of the existence of God, and 3) sensation gives us knowledge of the real world.6 If we do not have clear and certain knowledge of how our ideas agree or disagree, then we must use our judgment in order to unify or separate our ideas appropriately. Judgement is a faculty which enables us to unify or separate ideas according to their presumed, rather than known, agreement or disagreement.

Reason can extend only as far as our ideas extend. Reason may not always resolve the confusion caused by obscure and imperfect ideas. Reason may not resolve the difficulties caused by false assumptions, unless it is used to reject those false assumptions. However, reason may not always be necessary when the agreement or disagreement of ideas can be known intuitively.

Locke asserts that any truth which is discoverable by reason is also discoverable by divine revelation. However, we do not need divine revelation to discover truths which can be known by reason. Propositions which are contradicted by reason cannot be assumed to be verifiable by divine revelation. Indeed, we need reason to establish whether or not a proposition may be a divine revelation. Faith may convince us of the validity of something which cannot be known by reason. However, faith may not be able to prove the validity of something which is contradictory to reason. Faith is not by nature contradictory to reason. Thus, propositions which are contradictory to reason cannot be proven to have any validity by being called matters of faith.

Four main sources of errors of judgment which are described by Locke include: 1) lack of proofs for propositions, 2) inability to use proofs to verify propositions, 3) unwillingness to use proofs to verify propositions, and 4) use of wrong measures of probability.7

The sciences, or the disciplines of human knowledge, are divided by Locke into: 1) natural philosophy, 2) ethics, and 3) logic. Natural philosophy is concerned with whether things are knowable in themselves. Ethics is concerned with whether there are moral principles for human action. Logic is concerned with the correct use of signs (words and ideas) to discover and communicate knowledge.

Locke’s Essay Concerning Human Understanding offers important insights into how knowledge is attained through intuition, reason, and experience. Although Locke says that experience is the source of all our ideas, he does not say that experience is the only source of knowledge. Indeed, he says that knowledge of how all our ideas agree or disagree cannot be attained solely through experience. Intuition, reason, and experience may each produce knowledge of many truths, but each cannot separately produce knowledge of all truths. Thus, the faculty of understanding may combine these degrees of knowledge to produce a more unified knowledge which transcends the limits of intuition, reason, and experience.


FOOTNOTES

1John Locke, An Essay Concerning Human Understanding, edited by Peter H. Nidditch (Oxford: Oxford University Press, 1975), p. 128.
2Ibid., p. 525.
3Ibid., p. 533.
4Ibid., p. 538.
5Ibid., p. 562.
6Ibid., p. 618.
7Ibid., p. 706.

BIBLIOGRAPHY

Locke, John. An Essay Concerning Human Understanding. Edited by Peter H. Nidditch. Oxford: Oxford University Press, 1975.

Copywright© 2002 Alex Scott

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