Concerning Human Understanding by Locke
Aim: How has Locke succeeded in “clearing ground a little, and removing some of the rubbish that lies in the way to knowledge” [Epistle]?

The Epistle to the Reader
Locke contrasts Boyle, Sydenham, and especially Huygens & Newton as master-builders in the commonwealth of learning with his own employment “as an under-labourer in clearing ground a little, and removing some of the rubbish that lies in the way to knowledge,” whose advance is impeded by “uncouth, affected, or unintelligible terms, introduced into the sciences” and giving philosophy a bad name (par. 6).  He proposes to make clear and distinct ideas by giving terms fixed and determinate meanings, forming complex ones from the simples, these latter corresponding to “that simple appearance which the mind has in its view…when the idea is said to be in it.”  This will end the greater part of the doubts and disputes that perplex mankind.

Book One, Of Innate Ideas

Ch. 1, Introduction
2.  To achieve his design, to learn “the origin, certainty, and extent of human knowledge, [the topics of Book Four] together with the grounds and degrees of belief, opinion, and assent,” he will not consider the body and brain or their relation to the mind and its ideas but will use a “historical plain method” to consider the faculties as they are used on the object of experience.
6.  Man’s “business here is not to know all things, but those which concern our conduct.”  It is not important to know all but only how a rational creature in our circumstances would govern his opinions and actions.  The sailor’s line is long enough to measure depths near shore, not the depths of the ocean.
7.  First step for several inquiries must be to “examine our own powers” and not go beyond our powers “into the vast ocean of Being…”
8.  Idea is “whatsoever is the object of the understanding when a man thinks.”  First question is how they come into the mind.

Ch. 2, No innate principles in the mind
1.  We can show the falseness of the opinion that there are innate ideas [koinai ennoiai] by showing that all the knowledge men have may be attained without them.
2-5. Universal consent would not prove innateness of principles even if it did occur, which the examples of children and idiots prove it does not.  It is a contradiction to say that something is in the mind that it does not perceive or understand.  If “in mind” simply meant “capable of knowing”, all knowledge would be innate.  Since knowledge by reasoning is deduction from known principles, if the conclusion is also an innate principle, it would (at the start) be both known and unknown.
6-13. Nor can we say that these principles are known when the mind comes to the use of reason, because many of them are not present then and come, if ever, only when it forms general abstract ideas; e.g., ‘whatever is, is’.
14-16.  But even if they were known at that precise time, it would not prove their innateness, only their dependence on a particular faculty that needs to mature, just as general maxims are dependent on the use of language.  The mind is an “empty cabinet” furnished by the sense with “particular ideas”, which lodge in the memory and are given names, from which further more general names are abstracted.  These are the materials of its “discursive faculty”.  The discovery of knowledge begins as early as memory, when ideas are seen to agree or disagree.
17.  Nor is it a sign of innateness that there is ready assent as soon as a maxim is proposed, since many math and natural propositions are assented to as soon as understood, but their ideas are from the senses, not innate.
18-19. If this were the mark of innateness, countless particular maxims, dependent upon sense, and known before the more general maxims, would be innate.  All our ideas of color, etc., would be innate, but this is absurd.
23.  The underlying fallacy is that we are supposed not to learn anything new, when in truth we are taught and learn what we were ignorant of before.
24.  An innate truth not yet assented to is as unintelligible as knowing and yet being ignorant.  [See Ch. 2, paragraph 5.]
25.  Children know things, yet do not know the maxims supposed to be innate.
26.  Innate truth must be innate thought; if there is not thought, there is no knowledge to be innate.

Ch. 3, No innate practical principles [27 pars.]
1. No moral rule assented to as readily as the law of contradiction; ergo, even less claim to innateness.
2. Practice contradicts adherence, e.g., to justice.
3. Tacit assent meaningless if not practiced, for then they are most speculative principles.  There are natural appetites for the good, but these are not truths of the understanding.
4. There is no moral rule which does not require a reason; ergo, no principles.
5. Disagreement about the reason for, e.g., justice as the keeping of compacts.
9. Peoples of Asia, New World, often have different rules.
11. Even if innateness is compatible with not being followed in practice by some, it cannot be with all.
12. No innate principles either in the sense of being known or followed.  Duty is not understood without law, a law-maker, reward and punishment.
13. Principles of action in the appetites are not moral laws.  These laws are restraints to desire by means of reward and punishment.
15-19. Virtue, sin, etc., are of no use because the bounds of each are not innate.
25. Custom is the greater power than nature in matters of worship.
27. These principles upon which men place trust and do not question, ought in fact to be questioned and tested and are thus not innate.  There are none on which all agree, ergo, none innate.

Ch. 4, Other considerations concerning innate principles, both speculative and practical [no notes]

Book Two, Of Ideas

Ch. 1, Of ideas in general, and their original [25 pars.]
2.  The mind is a white paper [tabula rasa], furnished with ideas from experience, external and internal. [Cf. I, 2: “the mind is an empty cabinet”.]
3.  Senses are perceptions of things.
4.  Reflection is perceptions of operations of our own minds, including passions.
10.  The mind is not always thinking: we do not perceive it to do so; it is no more necessary than that the body should always move.  We possess soul even in sleep but if we think, then we are aware of it.
11.  Personal identity is impossible without consciousness of our own actions and sensations, especially pleasure and pain (see Ch. 7).
17.  A child has no ideas at birth (i.e., before sensation).
23.  Sensation is “an impression or motion made in some part of the body, as produces some perception in the understanding.”
24.  The first capacity of the mind is passive: to receive impressions, by sense or reflection.

Ch. 2, Of simple ideas [3 pars.]
1.  Qualities, though mixed in things, produce simple ideas in the mind.
2.  Simple ideas from sense and reflection cannot be made or destroyed by the mind, but can be united in almost endless variety to make new complex ideas.

Ch. 3, Of ideas of one sense [2 pars.]
1.  Some ideas come by one sense only, others by more than one [see Ch. 5], others by reflection only [see Ch. 6], others by all the senses and reflection [see Ch. 7].
2.  Needless and impossible to enumerate all the simple ideas from a single sense.

Ch. 4, Of solidity [5 pars.]
1.  No idea is received more constantly from the senses.  It is perceived only in masses of matter, but the mind infers it (as well as figure) in the minutest of particles, concluding that it is inherent in body.  [See Ch. 5.]
2.  What is solid, therefore, fills space; i.e., excludes other bodies.
3.  The idea of solidity is not the same as that of space.  Solidity includes resistance, motion, and hardness.
4.  The idea of solidity is not the same as that of hardness.  Hard and soft are relative, apply to the firm cohesion of masses of bodies that makes them resist change of shape. [But the solidity or fullness of body means that even the softest of bodies will not yield its place simultaneously to another.  I.e., two bodies cannot occupy the same space at the same time.]
5.  Solidity distinguishes the extension of body from the extension of space.  The latter is the cohesion of unsolid, inseparable, immovable parts.

Ch. 5, Of simple ideas of divers senses [1 par.]
These are the ideas of space (extension), figure, rest, and motion. [Aristotle’s common sensibles, Newton’s irreducibles, Descartes’ clear and distinct, and Spinoza’s adequate ideas.]

Ch. 6, Of simple ideas of reflection [2 pars.]
1.  The mind observes itself receiving and acting on ideas from sensation.
2.  Principal acts of the mind: perception (thinking) and volition.  Thinking includes remembering, discerning, reasoning, judging, knowledge and faith [discussed later].

Ch. 7, Simple ideas of sensation and reflection [10 pars.]
1.  Pleasure, pain, power [Ch. 21], existence, unity.
2.  Pleasure or pain are joined to almost all ideas.
3-4.  God gave us power to move, choose, act, think; God gave us pleasure and pain to excite these powers in pursuit and avoidance.
5.  Also, God gave us these to teach us, by want of complete happiness in all we enjoy, to seek it in enjoyment of Him.
7.  Existence and Unity: to think any idea is to think of its object as actual and one.
8.  Power: we observe our own ability to move parts of our own bodies.
9.  Succession: we observe our own ideas passing in train.
10.  All complex ideas arise from the above kinds.

Ch. 8, Some further considerations concerning our simple ideas [26 pars.]
1.  Each sensation is a positive idea, though its cause may be negative.
2.  E.g., cold and darkness are ideas that are not the same as the nature of the thing: “what kind of particles they must be, and how ranged…to make any object appear white or black.”
6.  and, can see darkness, though it is nothing but the absence of light.
7.  Most ideas are no more likenesses of things than names are of those ideas.
8.  Power to produce an idea is the quality of the thing.
9.  Qualities that are inseparable from the body – solidity, extension, figure, mobility [see Chapters 4 &5] – are original or primary qualities.
10.  The power to produce sensations in us, by “bulk, figure, texture, and motion” of insensible parts is secondary qualities, e.g., colors, sounds, tastes [see Chapter 1].
11.  Bodies produce ideas by impulse – the only means by which bodies operate.
12.  The motion of the nerves continues to the brain, or seat of sensation, to produce an idea in the mind.
13.  God annexes secondary qualities to the motions with no similitude to them, as He annexes pain to steel dividing flesh.  [Book Four, Ch. 3, par. 29: While some ideas are intrinsically related (“a right-lined triangle necessarily carries with it an equality of its angles to two right ones”), “the coherence and continuity of the parts of matter, the production of sensation in us of colors and sounds, etc., by impulse and motion – no, the original rules and communication of motion being such that we can discover no natural connection with any ideas we have in them – we cannot but ascribe them to the arbitrary will and good pleasure of the wise architect.”]
15.  Ideas of primary qualities resemble bodies; secondary do not.
18.  Secondary, like pain, are “effects of its operations on us.”
23.  Three sorts of qualities:
primary    –     in things
secondary –     power in things producing effects in us that we suppose to be in the
things, but are not
powers      –    in things and produce changes in other things that we recognize as                           effects rather than as qualities of the first things
25.  Since our senses are unable to discover any unlikeness between the idea of a secondary quality and the object producing it, we imagine them to be resemblances of it.

Ch. 9, Of perception [15 pars.]
1.  Perception is the first and simplest idea from reflection, often called thinking.
8.  Perception is often altered by judgment; e.g., the perception of a globe is of a flat circle.
10.  The mind is quick; custom facilitates.
11-14.  Perception and animals
15.  Perception is the first step toward knowledge.  The greater the variety of perceptions, the more knowledge.

Ch. 10, Of retention [10 pars.]
2.  Memory is not the storage of ideas as such, but a power to revive perceptions once had, with the additional perception that the mind had them before.  [Compare Sartre.]

Ch. 11, Of discerning, and other operations of the mind [17 pars.]
1.  Unless it has distinct perceptions of different objects and qualities, the mind is incapable of knowledge.  [See Book Four, Ch. 3, re maxims of agreement and disagreement of ideas.]

Ch. 12, Of complex ideas [8 pars.]
1.  Now consider mind as active (it is passive in reception of all simple ideas and in perception and memory):
a. combine several into compound idea; all complex ideas are made this way
b. compare any two ideas; ideas of relations
c. separate or abstract from accompanying ideas; general ideas
2.
3.  Complex ideas are modes, substances, or relations.
4.  Modes are complex ideas with no supposition of subsistence by themselves, but as dependencies on or affects of substances, such as triangle, gratitude, murder.  [Cf. Aristotle, Categories, “present in”.]
5.  Modes are simple or mixed.  Simple: numbers are combinations of units.  Mixed: beauty is a combination of color, figure, and delight in the beholder.
6.  Substances are combinations of simple ideas taken to represent distinct particular things subsisting by themselves.  Substances may be single or collective.  [Aristotle, Categories, “said of”.]
7.  Relations are comparisons of one idea with another.
8.  All ideas, even the most abstruse, are derived from sensation or reflection by the repetition and joining of ideas.

[Locke now considers several simple modes, such as space, duration, number, infinite, thinking, pleasure and pain, ending with power (Chapters 13-21).  Then he considers mixed modes (Ch. 22).  Then he moves to substance (Chs. 23 & 24), and finally to relations (Chs. 25-28).  He finishes with consideration of ideas as clear, real, adequate, true and their opposites (Chs. 29-32) and the association of ideas (Ch. 33).

Ch. 13, Of the simple modes of space [27 pars.]
[Locke’s atomism is evident in his treatment of space.  Space is the void, a kind of non-being that nonetheless is (par. 16), and is infinite.  Here and in Ch. 17, on infinity, the infinity of space is established by Lucretius’ argument (if we are at the end of the universe and throw a javelin, it would either hit an object or go off into empty space, etc.).  This atomism is, of course, also evident in the reduction of all secondary qualities to primary ones, the bulk, figure, number, situation, and motion of solid parts.]

Ch. 21, Of power [73 pars.]
The mind is passive with respect to all simple ideas, active in forming complex ones.  Power is itself a complex idea of a simple mode, i.e., one that involves the repetition of ideas in the mind, without regard to their content, except as one seems to be the agent, another the object of change.  This distinction, of active and passive power (par. 2), is best evidenced from reflection, in the acts of the mind, since bodies in motion are set in motion by other bodies, with no beginning or self-motion (pars. 4 & 72).
Since most of what we think about substances has to do with their effects on us (secondary qualities) and other things or of those things on them (powers), our ideas of substance are mostly about powers (Ch. 33, pars. 7-10).
As Locke explains in the next chapter, action being “the great business of mankind”, most of our ideas of mixed modes are about action and power.  This explains why the bulk of this chapter on power is about liberty.
Liberty     – the power to think or move or forebear
Necessity  – where to do or not is not within the agent’s power
Voluntary – what prefer to do, even if may be lacking liberty or power to do otherwise as well.  Not opposed to necessity, which may be what is preferred, but to the involuntary.  Ergo, we are not at liberty to think or not, when awake, but whether to think of this or that, just as we may move our bodies, but must be somewhere.  Will cannot be free or not; it is one power that an agent (man) has.  If, given a preference, a man can make it be, he is free.

Ch. 22, Of mixed modes [12 pars.]
Mixed modes arise less from observation of their ideas together, than from men’s thoughts.  They are mostly learned, not from experience, but by the definitions of words.  They arise “from an act of the mind combining…ideas” [par. 4] and given a name.  Thus, there is a name for killing a father, but not for killing an old man.  The choice of modes is based on “frequent use…in their way of living and conversation” [par. 5].
Most mixed modes are about action (thinking and motion) and power: “action being the great business of mankind” [par. 10].  Powers are habits and dispositions.  When power becomes actual it is a cause; the substance or mode produced is an effect.  Words of action often express only the effect: creation, annihilation, freezing.

Ch. 23, Of our complex ideas of substances [37 pars.]
1.  If there is a constant conjunction of some simple ideas, we give one name for all, thought of as the complex idea, with the supposition of a substratum for all the simple ideas, called “substance”.
2.  The idea of substance is the supposition of we “know not what support of such qualities” that produce simple ideas in us and are called accidents and the imagining that these qualities cannot subsist without support, like the earth on the tortoise: sub = under, stantia = standing, or up-holding.
3.  Ideas of particular sorts or kinds of substances are collections of simple ideas of properties that are “supposed to flow from the particular internal constitution or unknown essence of that substance.”
4.  Corporeal substances
5.  Thinking substances (minds)
8.  Powers are a great part of our ideas of substances, since they are distinguished mostly by secondary qualities.  [Indeed, it is the secondary qualities, for which Locke does not understand the connection with the primary qualities and powers of the thing, that seem to require the idea of substance most.  But we are also ignorant of how primary qualities hold together to form an essence, which for Locke seems to come down to the question of the cohesion of matter.  See par. 26.]
12.  We are fitted for the business of life to know and distinguish things for our use, but not to “have a perfect, clear, and adequate knowledge of them.”  If our senses wee more acute, we would know more of the parts of things, but then they would be less useful.
15.  Perception and idea of immaterial substance is as clear as that of material substance.
26.  We do not understand how droplets of water cohere and form ice.  But even if we did, we would still not know how the simplest particle coheres – and thus solid extended substance is as difficult to conceive as thinking immaterial substance.
27.  If matter is finite, there is a problem of coherence.
If matter is infinite, there are even worse problems!
28.  Active power: spirits.  Passive power: matter.  God: pure spirit, activity.
32.  Have few, superficial ideas of things, no knowledge of their internal constitution and true nature.
33.  Enlarging our ideas (of existence, power, knowledge, goodness, etc.) with the idea of infinity makes the complex idea of God (infinite substance).
35.  But God in his own essence is simple and uncompounded.

Ch. 24, Of collective ideas of substance [3 pars.]

Ch. 25, Of relation [11 pars.]
1. Comparison of one thing with another.
2. Where language supplies only one name, instead of 2 as it does in designating reciprocal relations, we are apt not to see the designated as relations and speak, e.g., of “external denominations”, such as “concubine”.
3. Other terms conceal tacit relations; e.g., “imperfect”, “great”, “old”.  [These are relative, rather than absolute.]
4. Can agree in idea of relations where disagree about the substances related.
7.   a. A large part of our thoughts and words.
8.   b. Often the ideas of relations are clearer and more distinct than those of the substances related.
9.   c. All relations, too, originate in simple ideas of sense or reflection.
10. d. All words about something other than the thing to which they are applied are relations.
11. [He will go on now to reduce all relations to simple ideas, starting with the “most comprehensive relation”, cause and effect.]

Ch. 26, Of cause and effect, and other relations [6 pars.]
1. We notice that things begin to exist from application and operation of some other being.  E.g., wax is made fluid by the application of heat, while wood is made ash by the application of fire.
2. Several kinds: creation, generation, making, alteration.  All kinds arise from ideas received by sensation or reflection.
3. Most designations of time and place, e.g., a year is a relation of our lives to revolutions of the sun; the date is related to Christ.
4. Young is the relation of a duration to a longer one.
5. Places and distances.

Ch. 27, Of identity and diversity [26 pars.]

Ch. 28, Of other relations [20 pars.]

Ch. 29, Of clear and obscure, distinct and confused ideas [16 pars.]
2. Clear ideas are as if from the objects themselves, not having faded and lost exactitude and freshness.
3. Cause of obscurity in simple ideas: dull organs, slight and transient impressions, weak memory.
4. Distinct  idea when mind perceives differences from all others.  Confused idea indistinguishable from another from which it ought to be differentiated.
6.  Cause of confusion in use of names [see Book III}:
7. a. complex idea made up of too few simples
8. b. or many, yet jumbled together, so correct name not clear
9. c. or by indeterminate application of names to different ideas
11. Prevent confusion: “collect and unite into our complex idea as precisely as is possible all those ingredients whereby it is differenced from others and…apply steadily the same name.”
13. Example of the chiliahedron.  Clear on the number, not the figure.
15. Example of eternity.  No clear idea of the quantity.
16. Example of infinitesimal parts.  Ditto.

Ch. 30, Of real and fantastical ideas [5 pars.]
•    In reference to the “things from whence they are taken”, ideas are real or fantastical, adequate or inadequate (Ch. 31), true or false (Ch. 32).
•    All simple ideas are real, but the 2ndary are not images or representations of what exists, being only “the effects of powers in things without us, ordained by our Maker to produce in us such sensations…the reality lying in that steady correspondence they have with the distinct constitutions of real beings.”
•    Man uses some liberty in forming complex ideas.  Mixed modes and relations have no other reality but what they have in the minds of men.  They need only be such that it is is possible that something exist conformable to them.
•    Some of our ideas of substances are real, when they are “such combinations of simple ideas as are really united and co-exist in things without us” [par. 5].

Ch. 31, Of adequate and inadequate ideas [14 pars.]
•    Adequate ideas perfectly represent those archetypes which the mind supposes them taken from, stand for, and refer to.
•    All simple ideas are adequate, since each corresponds to a specific power in the thing.
•    Complex ideas of modes cannot but be adequate, since they are the archetypes.  Complex ideas of substances are all inadequate because they are lacking with respect to the constitution on which all the properties depend.  If the complex idea of a substance were its real essence, the properties of the body would all be deducible from it, as are those of a triangle from its df.  The best we can do is to presume that the real essence “can be nothing but the figure, size, and connextion of its solid parts”, of which we have no idea [par. 6].  Most of our ideas about substances are powers and it is impossible that we should ever know all of those, since they have to do with relations with other bodies [par. 8].

Ch. 32, Of true and false ideas [25 pars.]
•    Strictly speaking, truth and falsity apply only to propositions, not ideas, which are so only with a tacit proposition, affirming or negating the idea.  “Whenever the mind refers any of its ideas to anything extraneous to them, they are then capable to be called true or false” [par. 4].  Cases: idea conformable to that in other minds; to some real existence; to some real essence [par. 5].
•    Double conformity of idea to thing and to name.
1.    Other minds.  Conformity to ideas of other men is liable to error, but simple ideas least so and mixed modes most.  A false idea of justice is nothing but one which does not agree with the ideas of other men [pars. 9-11].
2.    Conformity to real existence is liable to error only in the case of complex ideas of substances.  Simple ideas are all true, including 2ndary qualities, which would be so even if “the same object should produce in several men’s minds different ideas at the same time” [par. 15].  Nor, obviously, can modes be false, which are themselves the archetypes.  But all our ideas of substances are false as representations of unknown essences and some are false in conformity to real existences which include or exclude simple ideas they ought not.

Ch. 33, Of the association of ideas [19 pars.]
•    Even rational people have opinions whose “unreasonableness is usually imputed to education and prejudice, a kind of madness due to an association of ideas founded on chance or custom.  Very hard to separate, these ideas associated by custom follow one another as by nature or the motions of the animal spirits.  They include most feelings of sympathy and antipathy.  Importance of the care and nurture of children, whose impressions are often lasting, giving rise to superstitions, fears, and hates.
•    Intellectual habits and defects of this kind are frequent and powerful.  Example of association of being and matter, to the exclusion of spirit.  Source of “irreconcilable opposition between different sects of philosophy and religion.”

Book Three, Of Words

Ch. 3, Of General Terms
1.    All things that exist are particulars, but most words are general terms, the effect of reason and necessity.
2.    To name all things would be beyond human capacity.
3.    And it would not serve the purpose of communication to do so, since the ideas of particular things are peculiar to the minds that experience them and cannot be communicated.
4.    Nor would it be of any use for knowledge.  Although “founded in particular things, [it] enlarges itself by general views”.
5.    [omitted]
6.    General words are the signs of general ideas.  General ideas are formed by abstraction from any ideas “that may determine them to…particular existence”, such as the circumstances of time and place.
7.    The example of children developing general ideas by retaining “only what is common to all” they have experienced of a certain kind, such as man.
8.    In this way they advance to more general names and ideas, noticing things that both agree and disagree with their general ideas, such as animal.
9.    “General ideas are nothing but abstract ideas.”  So, by leaving out particulars, “the mind proceeds to body, substance, and at last to being, thing, and such universal terms which stand for any of our ideas whatsoever.”  The mystery of genera and species, of concern only in the schools, “is nothing else but abstract ideas…with names annexed to them.”
10.    Generic terms are useful in dfs because they sum up lists of the simple ideas involved in complex ideas and save us the labor of enumerating them.  But the best df enumerates them.  It is not necessary to define by genus and differentia, since they are merely convenient means to explain one word by several others.
11.    The general and universal are creatures of the understanding and “do not belong to the real existence of things”.  Ideas are general as signs or representatives of things and “universality does not belong to things themselves.”  Universals signify particulars and signification is a relation the mind adds to them.
12.    What do general words signify, since it cannot be one particular thing, nor a plurality.  It can only be “a sort of things”, by being the sign of an abstract idea.  The essences or “species of things are nothing else but these abstract ideas.”
13.    Abstract ideas, though they are “the workmanship of the understanding”, have “their foundation in the similitude of things.”  [Locke uses the term “form” to refer only to the observed similitude of things.]  The “supposed real essences of substances” is nothing but abstract ideas.
14.    [omitted]
15.    The real essence of substances is the “unknown constitution of things on which their discoverable qualities depend”.  This is original meaning of the term.  But the schools speak of it in terms of the artificial constitution of genus and species rather than the real constitution of things.  Essence in this sense means nothing but the abstract idea that each general name stands for.  The former, unknown essence is the real essence, whereas the latter is the nominal essence.
16.    The name can only be attributed to particular things that have the essence.
17.    There are two conceptions of real essence.  One takes them to be the “forms or molds, in which all natural things that exist are cast” and has “perplexed the knowledge of natural things.”  This hypothesis can no more explain monsters, etc., than one could explain circles with different properties.
18.    There is no distinction between real and nominal essence as applied to simple ideas and modes.  E.g., the very essence of a triangle and the abstract idea of a 3-sided figure are the same.  But they are different as applied to substances.  The real essence of Locke’s gold ring is “the real constitution of its insensible parts”, for which we have neither idea nor name.  The sensible properties that depend upon this real constitution form the complex idea to which we attach the name and are thus its nominal essence.

Ch. 6, Of the Names of Substances

1.    Common names stand for the complex ideas in which particulars agree, as the names of substances and other general terms.  They are names of sorts of things.  So if there are other things like the sun, as some say the stars are, then they may be called suns too.  This shows the dependence of such names on the collections of ideas men happen to make.
2.    [Here Locke again distinguishes real and nominal essence.]
3.    Knowing that “man” refers to voluntary motion, sense, reason, and a body of a certain shape is not the same as knowing how those are united and operate.  Locke compares knowing the real essence to knowing a clock’s mechanism.
4.    Essence applies to sorts and not to particular things, or individuals, as such.  The essential and not essential are questions of whether a particular being is to be counted as one sort or another, i.e., they relate to abstract ideas and names.
5.    Locke illustrates with his and Descartes’ different ideas of body as solidity and extension, respectively, showing that essential means part of the complex idea the name stands for.
6.    Even the real essence relates to a sort and supposes a species, being the real constitution of the properties common to things of that kind.  Aside from “the consideration of [the particular thing] being ranked under the name of some abstract idea… there is nothing necessary to it, nothing inseparable from it.”  [I.e., although there is a real, if unknown, unity of the sensible properties, there could be other things with a different set of properties.]
7.    Only the nominal essence organizes things into kinds.
8.    That it is not the real essence that distinguishes them is evident from the fact that there are differences among the individuals of a species as real and as great as those that distinguish them from other species.
9.    We do not know the real essences of things, our faculties being limited to their sensible ideas.  We cannot know what makes lead and antimony fusible, while wood and stones are not or lead and iron malleable, while antimony and stones are not.  The workmanship of the wise maker of the fabric of the universe exceeds far more the capacity of the most intelligent man than any contrivance of the latter does that of the most ignorant of men.
10.    [omitted]
11.    [omitted]
12.    Since we see no chasms or gaps in the visible corporeal world, it is probable that the same holds in the spiritual, so that there may be many species of spirits.  The differences among brutes suggest that species are linked together and “differ in almost insensible degrees”.  [Compare this point, made here and elsewhere by Locke, with Darwin’s point about species and variations.]
13.    [omitted]
14.    The idea of a set number of species requires assumptions:
15.    That nature always designs things to partake of certain essences.
16.    That nature always attains that design in producing things.
17.    That monsters are not distinct species.
18.    Real essences ought to be known.
19.    Our complex ideas should be complete collections that flow from the real essences so that we can tell whether something is truly of that essence, but we are ignorant of many of their properties.
20.    [omitted]
21.    [omitted]
22.    [omitted]
23.    [omitted]
24.    [omitted]
25.    [omitted]
26.    Nominal essences are made by the mind, not by nature, as is evident from the fact that they vary among men.
27.    [omitted]
28.    But the nominal essences of substances “are not yet made so arbitrarily as those of mixed modes…the mind, in making its complex ideas of substances only follows nature.”
29.    But it follows nature only imperfectly, since “the number [or properties] it combines depends upon the various, care, industry, or fancy of him that makes it.”
30.    [omitted]
31.    [omitted]
32.    The more general ideas are, the more incomplete, since they leave out those qualities that distinguish things.
33.    [omitted]
34.    [omitted]
35.    [omitted]
36.    Nature makes the similitudes of things, but this is not the real essence; it is men that range them into sorts for the convenience of comprehensive signs.

Ch. 11, Of the remedies of the foregoing imperfections and abuses
•    Cannot move all language users to reform, but “those who pretend seriously to search after or maintain truth, should think themselves obliged to study how they might deliver themselves without obscurity, doubtfulness, or equivocation…”  Thoughts are often fixed only on words, especially in morals, with “very confused or very unsteady” or no ideas at all.  This misleads in “private meditations” and even more in “arguings with others”.
•    Not having the same complex idea in mind when they use names, controversies arise: it is possible that “the greatest part of the disputes in the world are…merely verbal and about the signification of words…”  “To remedy the defects of speech”, he offers five rules:
1.    Take care to use no word without a signification.
2.    Simple ideas must be clear and distinct, complex ones determinate. (Examples of mixed modes and substances.)
3.    Take care to apply words to such ideas as common use has annexed them to.
4.    Declare meanings where common use has left them uncertain and loose, especially where the discourse turns on them.  Ways of making known the proper signification of words:
a.    simple ideas  – synonyms, names of subjects, showing
b.    mixed modes – df.  Possibility of moral demonstrations.
c.    Substances    – Showing and defining by “leading sensible qualities and enumeration of simple ideas that are hidden powers.
The senses are the source of knowledge of corporeal things.  How spirits get ideas is beyond comprehension.  [Innate ideas?]  To make names conformable to things, need inquiry and natural history.  If such inquirers would set down the simple ideas, etc., such a dictionary of natural history would remove disputes.
5.    Use same word constantly in the same sense.

Book Four, Of Knowledge and Opinion

Ch. 1, Of knowledge in general [9 pars.]
•    Our knowledge is about our ideas; their agreement or disagreement.  This is of 4 kinds:
1.    identity and diversity
2.    relation
3.    co-existence or necessary connection [subsistence and inherence]
4.    real existence
•    They compare ideas, respectively, with themselves, with other ideas, with a substance, and with actual real existence.  [Cf. Aristotle’s 4 scientific questions at the beginning of Book II of the Posterior Analytics.]  Knowledge may be actual or habitual (memory).

Ch. 2, Of the degrees of our knowledge [15 pars.]
•    Intuition is the most certain.  Perceives agreement and disagreement of ideas.  Where this cannot be seen immediately, we look for intermediate terms: reasoning; where clear, it is demonstration, which is not as certain as when we see the relation between two ideas at once.
•    Demonstration is not only possible about quantity, but other simple ideas must be made precise to make demonstration possible.
•    We also know the existence of things, by sensation, but with less certainty than intuition and demonstration provide.  We perceive the difference between perception and memory.  If someone says all could be a dream, then reasoning would not matter.  [Note the pragmatic criterion.]  But dreaming of being in a fire is not the same as being in one!  But if he says the pain too is a dream, then Locke says our “certainty is as great as our happiness or misery, beyond which we have no concernment to know or to be.”  [See Ch. 11, par. 8.]
•    The degree of knowledge is a matter of clarity of relations of ideas, but this is possible only if the ideas are clear, or rather, if you have a clear relation of ideas to words used in propositions.

Ch. 3, Of the extent of human knowledge [31 pars.]
•    Knowledge is limited by the extent of our ideas.  But also by awareness of their agreement and disagreement with each other, by intuition and proof, and with things, by sensation.
•    As an example, Locke argues that we cannot so relate our ideas of matter and thinking as to know whether it be possible for a material thing to think or whether this can only be accounted for by a spiritual substance.  We cannot know how secondary qualities are produced in us by the motions of bodies; why cannot they be produced in a material being?
•    All the ends of morality and religion are served either way, since whatever the nature of the mind, none can doubt that God could revive it after this life “to receive the retribution he has designed to men.”
•    So much for the limitations, now for the extent of our knowledge.  [For the 4 following items, see Four, Ch. 1, pars. 2-7.]
1st Identity & diversity: The extent of intuitive knowledge equals the extent of all our ideas.  [I.e., we can tell that the idea of the interior angles of a triangle is different from the idea of 180 degrees, though we cannot tell (by intuition) how many degrees those angles are; we cannot know the connection of equality between the two ideas except by means of demonstration (intervening ideas).]
2nd Agreement & disagreement of our ideas in co-existence: this is most of our knowledge of substances, but is very little, for we know only that simple ideas co-exist, for we cannot know their connection, either of 2ndary qualities with each other or with the primary qualities that produce them.  We know only some relations between primary qualities, of extension and figure and motion, but only what our senses report of co-existence for the rest.  We are much more in the dark in reference to spirits, which we know only by reflection on our own souls, in ignorance of any nobler kinds.
3rd Agreement & disagreement of ideas not in co-existence: the largest field of our knowledge and the hardest to know the extent, since it consists in finding intermediate ideas to make demonstrations.  It has been done to a wondrous degree in mathematics, but Locke is convinced it is not limited to ideas of quantity.  [See discussion of lack of precision in 2ndary qualities, Book Two, Ch. 2, pars. 9-13.]  Morality is capable of demonstration.  Advantages of quantity: clear notation, sensible marks; moral ideas are more complex, uncertain signification of names, complicated combinations and long deductions.  The obstacle to making morals a deductive science is men’s passions, desire for esteem, power, wealth.
4th Knowledge of actual existence of things: intuition of our own existence, demonstration of God, sensitive of other things.
•    Ignorance  due to:
1.    want of ideas due to limits of faculties, remoteness or minuteness of things; ergo, no science of bodies, much less spirits.
2.    want of connections between ideas we do have; between primary and 2ndary ideas; will and bodily motion.  There are some necessary connections we can know between our ideas, such as the equality of the angles of a triangle to 180 degrees, but most are otherwise.  “But the coherence and continuity of the parts of matter, the production of sensation in us of colours and sounds, etc., by impulse and motion, nay, the original rules and communication of motion being such wherein we can discover no natural connexion with any ideas we have, we cannot but ascribe them to the arbitrary will and good pleasure of the wise Architect” [par. 29].
3.    want of tracing connections we are capable of [here lies the utility of his geometric method; see Ch. 12, pars. 3 & 7]; limits regarding the universality of knowledge discussed in the next chapters [5-8].

Ch. 4, Of the reality of knowledge [17 pars.]
4. simple ideas are not fictions, but products of things
5. all complex ideas save of substance [irony, since only substances are realities outside our minds]
6. ergo, the reality of mathematical knowledge
7. moral can be
12. substances often not, but can be when simple ideas co-exist in nature
13. misled by words to think we know species

Ch. 6, Of universal propositions, their truth and certainty [16 pars.]
•    If use general terms, species or essences, must know them.  But with substances they stand for “we know not what”.  As nominal essences they are known, but undeterminate in reference.  Examples of gold as ‘fixed’ or ‘malleable’.
•    If could discover the necessary connections between two qualities, would know a universal proposition to be true.
•    Qualities of substances mostly depend on remote, external causes.  Would need to know the effects of primary qualities in other bodies and our minds.
•    Agreement and disagreement found in ideas only.  When go beyond to things, in experiment or observation, knowledge is limited to particulars.  [Ch. 9 shows corporeal existence is known by sensation.]

Ch. 7, Of maxims [19 pars.]
•    Many maxims are self-evident, but so are many propositions which are instances of them and are neither later in time nor depend upon the maxims to be understood.  All ideas are self-evidently known to be identical with or diverse from other ideas we have.  But there are few self-evident propositions about co-existence.  There are many in modes, e.g., mathematics.  There are none in real existence.
•     Maxims are of use in teaching sciences, not in discovering them, and in disputations.

Ch. 8, Of trifling propositions [3 pars.]
These merely report the meaning of a word or predicate part of its whole.

Ch. 9, Of our knowledge of existence [3 pars.]
There is no certainty about universal propositions of existence.  The self is known by intuition; God by demonstration; things by sensation.

Ch. 10, Of our knowledge of the existence of God [19 pars.]
1.    From the necessity of our own existence and the necessity of a cause, we can infer existence from eternity.  Eternal source is the cause of all power.  Existence of knowledge, likewise, permits us to conclude that there is an eternal source of all knowledge.  It cannot come from “senseless matter”.
2.    Weakness of the proof from the idea of a most perfect being.
3.    Matter alone can produce nothing, is inert.  Even its motion is due to another.  Matter and motion could not produce thought.

Ch. 11, Of our knowledge of the existence of other things [14 pars.]
1. known only by sensation
3. not so certain as demonstration; can produce own pleasure and pain
4. sense organs
5. involuntary reception
6. sense distinguished by accompaniment of pleasure and pain
8. if all a dream it does not matter; certainty sufficient for our needs and preservation
11. past existence known by memory
12. no knowledge of spirits, other than God, because not available to sense

Ch. 12, Of the improvement of our knowledge [15 pars.]
3. Advance of knowledge not due to deduction from maxims or general principles, as seems to be the case in mathematics, but from “clear, distinct, complete ideas” which can easily be compared regarding equality and excess, without the help of maxims.
7. Thus, use of the method of mathematics on other ideas, that are real essences of their species, would produce great knowledge.
8. Morality can be demonstration.
9. But knowledge of substances depends on a different method, since we lack suitable ideas.  Turn from our thoughts to things themselves.  “Experience here must teach me what reason cannot…we can go no futher than the simple ideas of our nominal essence will carry us, which is very little beyond themselves and so afford us but very sparingly any certain, universal and useful truths…there is no necessary connexion or inconsistency to be discovered betwixt…yellow, heavy, fusible, malleable…and fixedness…for assurance I must apply myself to experience; as far as that reaches I may  have certain knowledge, but no further.”
10. From experience we form judgments and opinions about bodies, but lack knowledge and certainty.
11. Follows that our duty is to apply reason to God and morals.
14. Whether or not certainty is possible in natural philosophy, “the ways to enlarge our knowledge” are two:
Knowledge enlarged by clear and distinct ideas with settled names, and then finding their agreement or disagreement.  The method is to
a. search for determinate ideas and as complete description of substances as possible, and then
b. search for intermediates “which may show us the agreement or repugnancy of other ideas which cannot be immediately compared.”
15. These two and not relying on maxims and drawing consequences from general propositions are the right method of improving our knowledge.

Ch. 15, Of Probability  [6 pars.]
1.    Demonstration shows the agreement or disagreement of two ideas by intermediate ideas whose connections are intuitively known and so perceives their certain, immutable connection.  Probability is the appearance of such agreement or disagreement by proofs whose connection is not constant and immutable but is enough to induce assent.
2.    Our knowledge is very narrow, most of what we think and act upon have a degree of assurance from near certainty to doubt and distrust.
3.    The difference between probability and certainty, faith and knowledge is that “in all the parts of knowledge there is intuition…in belief, not so.  That which makes me believe is something extraneous to the thing”.
4.    The grounds of probability are either “our own knowledge, observation, and experience”, as when we have seen a man walk on ice and then are told of the same; or the testimony of others, which depend for their strength on how many say so, their integrity, their skill, their purposes, the internal consistency of their report, and contrary testimonies.
5.    Lacking intuitive evidence and certain knowledge, one ought to examine all the grounds of probability and weight them. When a man of the tropics is told that people in Holland walk on hard water, he may be permitted his skepticism.
6.    Men often rely upon the opinion of others, but that is not a true ground of probability “since there is much more falsehood and error among men than truth and knowledge.”  And following it means changing religion as one goes from one country to another.

Ch. 16, Of the Degrees of Assent
1.    Since it is hard to retain all the proofs, men assent from memory.  It suffices if they have once searched with care and cast up an account of the whole evidence
2.    It is unavoidable that memory be relied upon and men be persuaded when the proofs are not actually in their thoughts.  Otherwise they would have to be skeptics or yield to the most recent arguments “which, for want of memory, they are not able presently to answer.”
3.    This obstinacy is often the cause of error because they judged before they had well examined, not because of the use of memory.  Some think they are right because they have never thought otherwise.  But with probability we can never be secure that we have all the particulars and no evidence is unseen.  Yet we must decide, since life will not bear delay.
4.    Since it is not reasonable to expect men to change their opinions even when we give a good argument, it would “become all men to maintain peace, and the common offices of humanity, and friendship, in the diversity of opinions”.  We ought not to expect him to forsake the leisure of consideration we use ourselves or, if he takes things on trust, to forsake opinions taught to him by those he considers sent by God.  Those who have “got past doubt in all the doctrines they profess and govern themselves by” have better reason to insist that others agree, but they are so few in number and are such that “nothing insolent and imperious is to be expected from them”.
5.    Inducements of probability either concern some particular existence capable of being witnessed or are beyond the discovery of our senses.
6.    First, if we and others all observe the same thing, we build upon it as equivalent to certain knowledge.  We conclude what is observed is the effect of regular causes, even when we don’t know them.  This is assurance.
7.    Second, the next degree of probability is that which I and others find “to be for the most part so”, as that “most men prefer their private advantage to the public.”  This is confidence.
8.    Thirdly, for things that occur indifferently, when there is testimony of reliable witnesses that they occurred this way rather than that, e.g. that Julius Caesar lived 1700 years ago, “a man cannot avoid believing it and can as little doubt of it as he does of the being and actions of his own acquaintance”.
9.    So far we are as little free to disbelieve as in the case of demonstration.  But when testimonies contradict and reports clash with the ordinary course of nature, diligence is required to form a right judgment.  The evidence may be so varied that “it is impossible to reduce to precise rules the various degrees wherein men give their assent.”  Degrees of preponderance of evidence are called belief, conjecture, guess, doubt, wavering, distrust, disbelief, etc.
10.    By the law of England, though the attested copy of a record be good proof, the copy of a copy, however well attested, will not be admitted as a proof.  Thus, in general, the further testimony is from the original truth, the less force it has.  But some men believe the opposite, that the further away and older opinions are, the more force they have.  So what was originally false comes to be probable and then authentic truth.
11.     This is not to lessen the importance of history and the value of records from antiquity.  But no truth can rise higher than its original.  For the accuracy of quotations we need the originals.
12.    The other sort of probability (not matter of fact) are those not capable of testimony: the existence of finite immaterial beings or tiny material ones; the hidden causes in nature.  In these matters analogy is the only help we have and the ground of probability.  Example of the analogy between friction and all instances of heat and of color.  Thus by analogy with perceived nature we may infer with probability that “things ascend upwards in degrees of perfection.”  “This sort of probability, which is the best conduct of rational experiments…and a way reasoning from analogy leads us often into the discovery of truths and useful productions, which would otherwise lie concealed.”
13.     Common experience has a mighty influence on the mind.  But in one case the strangeness of the fact does not lessen assent, “where such supernatural events are suitable to ends aimed at by him who has the power to change the course of nature”: this is the case of miracles.  They not only are credible themselves “but give it also to other truths which need such confirmation.”
14.     The testimony of God, who cannot deceive or be deceived, demands the “highest degree of our assent, upon bare testimony”, whether it disagrees with common experience or not.  This assurance beyond doubt is called revelation and our assent to it is faith.  We only must be sure that it is a divine revelation and that we understand it rightly and it is not the result of our enthusiasm.