Book II of the Essay Concerning Human Understanding is where Locke begins his positive account of knowledge, but explaining what kinds of ideas we have. This account culminates in Book IV when he sets out his account of knowledge, and the different things which we can and cannot know. As the selections we are reading are all from Book II of the Essay, we are going to focus on Locke account of the origins of ideas in sensation and reflection (Chapters 1-12 of Book II, the distinction between simple and complex ideas, the distinction between primary and secondary qualities and the distinctions between substances, modes and relations. We will consider some comparisons and contrasts with Descartes. We will also consider Locke's account of free will as a transition to his political writings.

Locke on ideas -- perception and reflection, simple and complex. Chapters 1 through 8

This section is intended to guide you through the first eight chapters of Book II of An Essay Concerning Human Understanding.

The term 'idea,' Locke tells us "...stands for whatsoever is the Object of the Understanding, when a man thinks." (Essay I, 1, 8, 25) This is similar to the account which Descartes gives of ideas. Thus, in his reply to the third objections to the Meditations, Descartes writes: "But I make it quite clear in several places throughout the book...that I am taking the word 'idea' to refer to whatever is immediately perceived by the mind." (Descartes, Selected Philosophical Writings, trans. Cottingham, Cambridge University Press, Cambridge, 1988. Pg. 132) Descartes and many other philosophers and theologians during this period believed in innate ideas and principles. Locke devotes the first book of the Essay to a refutation of the doctrine that there are innate ideas and principles. Having set aside the possibility of innate ideas, Locke announces at the beginning of Book II of the Essay that our ideas originate from two sources -- from sensation and reflection.

Locke's rejection of innate ideas and his claim that the mind is a blank tablet before experience writes on it, marks a significant difference between Locke and Descartes. Locke accepts while Descartes rejects what is often called the empiricist axiom -- that there is nothing in the intellect which was not previously in the senses. This has led historians of philosophy to characterize Locke as an empiricist, along with Berkeley and Hume; while characterizing Descartes, along with Spinoza and Leibniz, as rationalists. It is true that all of the philosophers in the first group reject innate ideas and accept the empiricist axiom on one interpretation or another; while all the philosophers in the second group hold that their are innate ideas, and reject the empiricist axiom. It is also true that all of the philosophers in the first group, often called the British Empiricists, reject the Ontological argument for the existence of God; while all the philosophers in the second group, often called Continental Rationalists, accept some form of the Ontological argument. This argument purports to prove that God exists from the definition of God. Recent scholars have argued persuasively that the contrast between empiricists and rationalists has been much too over simplified, and that all of these philsophers have much in common. Still, grasping the distinction between rationalism and empiricism is probably a good place for someone beginning a study of this period to start.

For Locke, ideas in the mind correspond to qualities in objects (See Chapter VIII, 8.) In Book II, Chapter III we learn of simple ideas such as 'white' or 'cold' derived from a single sense. In Chapter V Locke men tions other simple ideas, such as extension, figure, rest or motion, which are derived from more than one sense. Thus, we learn about extension from both touch and sight. Chapter VI explores simple ideas derived from reflection rather than sensation. Our ideas of the faculties of the will and understanding are such simple ideas of reflections. Ideas such as remembrance, discerning, reasoning, ju dging, knowledge and faith are modes of the will and understanding. These ideas stand for operations of the understanding itself. In Chapter VII Locke explore s ideas derived from both sensation and reflection. These include pleasure and pain, power, existence and unity.

Locke, unlike Descartes, is an atomist. The two basic constituents of the world for an atomist are atoms and the void space between them and in which they move. Descartes is a plenum theorist -- that is, like Aristotle, he believes the universe is filled with matter and there is no void or vacuum. Thus the essential property of a body for Descartes is simply that it occupy space, for there is no space apart from body. For Descartes, there are bodies of different kinds, some densier, some more raref ied (he has three classes of matter), so that those of the second and third class can move through the less denser ones. For Locke, on the other hand, in order for something to be a body it must not only occupy space, but it must be solid or impenetrabl e as well. Thus Chapter IV "Of Solidity" serves to distinguish the Lockean conception of bodies from that of Descartes. On the one hand Locke distinguishes sol idity from space, and on the other hand solidity from hardness.

Locke on the distinction between primary and secondary qualities

We have already had some occasion to concern ourselves with this distinction which Locke makes in Chapter VIII between primary and secondary qualities. Descartes makes a similar distinction in the wax example in the Meditation II section 11. The distinction itself goes back to the Greek atomis ts. In spite of its antiquity, however, the distinction is so important to modern philosophy (Descartes to Hume) that David Hume says it characterizes modern philosophy.

The distinction between primary and secondary qualities captures the difference between the ways things are independently of how we perceive them, and those qualities of things which depend on how we perceive them. Thus, a tower or mountain presumabl y occupies space and remains (relatively) at rest, whether we perceive it or not. But the fact that the mountain appears purple from a distance is an artifact of the interaction of the object with a particular kind of perceptual apparatus. Dogs, for exa mple, have no color receptors in their eyes, thus they see the world in shades of black and white. Human beings, who do have color receptors, see the world as a multiplicity of colors. Without a human perceptual apparatus, there would be light rays, and absorption of light rays, but no perceived color.

What are the primary qualities, and what are the secondary ones? Extension, figure, number and motion of bodies large enough to be observed is the list which Locke gives first. (II. 8, 12) These qualities produce in us the ideas of primary qualities. The secondary qualities are colors, such as white, violent and green; tastes, smells, and sounds. The primary qualities produce the ideas of secondary qual ities by interacting with our perceptual apparatus. Thus without eyes and brains/minds, while there would be objects which absorb various light rays and light, there would be no perceived color. Without noses, nerves, brains and minds there would be no p erceived smells and so on.

Locke goes on to observe (II, 8, 15) that the ideas of primary qualites resemble the properties in the objects which they represent, while this is not true of secondary qualities. Thus he says: "...that the ideas of primary qualities of bodies are res emblances of them, and their patterns do really exist in the bodies themselves, but the ideas produced in us by these secondary qualities have no resemblance of them at all."

The distinction connects skepticism, science and philosophy in interesting ways. One of the strands of skeptical thinking holds that the variability of our perceptions shows that they are mind dependent, and because reality is determinate, this varia bility shows that we are grasping appearance and not reality. Thus if you see an oar as bent and I see it as straight, we know that it cannot be both, it must be one or the other. But since we see it both ways, we have appearance and not reality. In fa ct, one of Locke's most famous examples (used by Berkeley as well) -- that of dipping a hand which is warm and the other hand which is cold into a bucket of water -- we find in Montaigne. But the scientist differs from the skeptic in holding that we can distinguish appearance from reality, we can tell which properties of things they have independently of us, and which depend on our perception. So, the skeptic sees all properties as appearance, while the scientists see only some properties as apparant, a nd others as representing reality. Thus, the distinction between primary and secondary qualities implies that we can know objective reality in a way which the skeptic denies is possible.

Substances, Modes and Relations -- Chapter 12

The distinction between modes and substances is a fundamental one in Locke's philosophy. Material substances are external objects. We try to grasp the nature of these objects and to represent what we have grasped by creating an idea. We put into this complex idea those simple ideas which correspond to the qualites which we find in the object. Some properties are apparent and others are not; some are easy to grasp and others are not. On the whole, mankind made up as it is of cooks and tailors, lovers and fisherfolk, make ideas, and language, for quite pragmatic and ordinary purposes. Scientists come along latter to try to determine if the connections between properties which the ordinary folk have put together in a particular idea as represented by it in a corresponding word, in fact holds in nature. Sometimes, the scientists may find that the ordinary folk have erred, as when they called whales fish. A whale is not a fish, as it turns out, but a mammal. There is a characteristic group of qulities which fish have which whales do not have. There is a characteristic group of qualites which mammals have which whales also have. To classify a whale as a fish therefore is a mistake. Similarly, we might make an idea of gold which only included being a soft metal and gold color. If so, we would be unable to distinguish between gold and fool's gold. Unfortunately for our knowledge of material substances and thus science, on Locke's view we can never really get at the clockwork which produces the apparent qualities we do perceive. The most that even scientists can do is to try to determine if apparent qualities are always connected in nature. But the underlying machinery which causes to qualities to always appear together is hidden from us.

In Book IV, Locke illustrates this point by comparing our situation to that of a gazing countryman who comes to see the great clock at Strasbourg. This clock was a mechanical marvel of its time. The clock was built in 1570-74. At ground level the main features were, in the center a three foot astronomical globe with a 24 hour movement, and behind it a 10 foot rotating calender and clock, recording years and months, days and nights, equinoxes and festivals; above this presided the titular deity for the day of the week. Two fixed side panels recorded the eclipses. At first floor level the central astrolabe plotted the position of the planets in the zodiac and marked the hours, minutes and quarters were shown by the dial at the front of the balustrade. The dial above the astrolabe depicted the current phase of the moon. At the third level, rotating jacks struck the quarter hours and Death the hours. The whole struc ture was elaborately sculpted and painted with religious, allegorical and secular motifs. The tower on the left housed the weights and was surmounted by a mechanical cocherel, which sprang into life after each carrillon but was damaged by lightening in t he early seventeenth century. The clock was derilict by the late eighteenth century and was redesigned and rebuilt in 1839-42.

The great clock at Strasbourg was used by a variety of philosophers in the 17th and 18th century as an analogue or model for the universe which suggested that God was a great clockmaker. So, Locke is saying that while we can come and be astonished by the outward appearances of things (as the gazing countryman is of the outward marvels of the clock), we can never get at the inner springs and wheels (the organization of the atomic constitution of material substances), which are known only to the clockma ker (God) and his assistants (the angels). As a result, our ideas of material substances are always likely to be inaequate, and our knowledge of the material world, such as it is, is of the lowest kind. In fact, in Book IV Locke does not even call this kind of cognition knowledge.

Our ideas of modes are remarkably different from our ideas of substances. Our ideas of modes are complex ideas, just as our ideas of substances are. So we make such ideas, rather than passively receivng them. But the archetype of the ideas of mode s is not external. Rather the ideas themselves are the archetype. Rather than measuring the adequacy of our idea by comparing it with the external archetype which we seek to copy and represent as we do with substances, we take the ideas of modes to be p erfect, and simply ask whether things in the world have the characteristic group of simple ideas in that mode or does not. If a thing does, we call it by the word corresponding to that modal idea, if not, then we deny that that name applies. Thus, havin g made the idea of 'bachelor' our of 'umarried' and 'adult human male' -- we can go around determining who is a bachelor and who is not. When we find an adult human male who is not unmarried, this does not cause is to reflect that there is something inad equate about our idea of bachelor. Rather we simply conclude that that term does nor apply to this person. The implications for knowledge are profound. We can know modal objects perfectly, in a way in which knowledge of substances is not possible. The objects of mathematics, such a numbers, and geometrical figures like triangles, circles, and squares are all modal ideas. As a consequence it is possible to have a deductive science of mathematics.

Science and Knowledge of Morality

Because ethical ideas are modes, Locke holds out the possibility that there might be a deductive science of morality, just as their is a deductive science of mathematics. Thus, in principle it is possible for us to know the nature of morality with complete certainty, and thus to guide our conduct with some assurance. It is striking that in this age of incredible scientific advancement, of which Locke was perfectly aware, Locke is much more pesimistic about the possibility of scientific knowledge than he is about the knowledge of morality.

The Limits of Human Understanding

Having developed all the machinery he feels necessary, in Book IV of the Essay Locke explains the nature of knowledge and what humans are capable of knowing. There are some four degrees of knowledge. The first is intuitive knowledge, the kind of thing which we get by the natural light, that two ideas are the same or different is intuitively obvious to us. Nothing could be more certain. Second, there are truths which are known demonstartively. Demonstation depends on having an intuitive grasp of the connection between the ideas in each of the steps of the proof. The third level of knowledge is that of the existence of external object. Here a comparison with Descartes is of some interest. Locke writes: "These two, viz. intuition and demonstration, are the degrees of our knowledge; whatever comes short of one of these, with what assurance soever embraced, is but faith or opinion, but not knowledge, at least in all general truths." He continues: "There is, indeed, another perception of the mind, employed about the particular existence of finite beings without us, which, going beyond bare probability, and yet not reaching perfectly to either of the foregoing degrees of certainty, passes under the name of knowledge." The reason why our knowledge of the existence of external objects is less assured is a certain skeptical challenge: How do we know that there is something in the external world which corresponds to our ideas?

There can be nothing more certain than that the idea we receive from an external object is in our minds: this is intuitive knowledge. But whether there be anything more than barely that idea in our minds; whether we can thence certainly infer the existence of anything without us, which corresponds to that idea, is that whereof some men think there may be a question made; because men may have such ideas in their minds, when no such thing exists, no such object affects their senses.

Thus, we might as Descartes considered, be dreaming or being deceived by an evil demon. Locke's thinks there is a clear difference between our ideas when we look at the sun by day or remember it later:

But yet here I think we are provided with an evidence that puts us past doubting. For I ask any one, Whether he be not invincibly conscious to himself of a different perception, when he looks on the sun by day, and thinks on it by night; when he actually tastes wormwood, or smells a rose, or only thinks on that savour or odour? We as plainly find the difference there is between any idea revived in our minds by our own memory, and actually coming into our minds by our senses, as we do between any two distinct ideas.

And thus if anyone thinks he might be dreaming, Locke gives this response:

If any one say, a dream may do the same thing, and all these ideas may be produced in us without any external objects; he may please to dream that I make him this answer:- 1. That it is no great matter, whether I remove his scruple or no: where all is but dream, reasoning and arguments are of no use, truth and knowledge nothing. 2. That I believe he will allow a very manifest difference between dreaming of being in the fire, and being actually in it. But yet if he be resolved to appear so sceptical as to maintain, that what I call being actually in the fire is nothing but a dream; and that we cannot thereby certainly know, that any such thing as fire actually exists without us: I answer, That we certainly finding that pleasure or pain follows upon the application of certain objects to us, whose existence we perceive, or dream that we perceive, by our senses; this certainty is as great as our happiness or misery, beyond which we have no concernment to know or to be. So that, I think, we may add to the two former sorts of knowledge this also, of the existence of particular external objects, by that perception and consciousness we have of the actual entrance of ideas from them, and allow these three degrees of knowledge, viz. intuitive, demonstrative, and sensitive: in each of which there are different degrees and ways of evidence and certainty.

Our knowledge of the nature of existing objects is even more problematic than our knowledge that they exist.

Free Will

In Chapter XXI of Book II, the Chapter "Of Power" Locke gives us his account of free will. There are a three basic views about free will which have philosophers have advocated over the last three centuries. Part of what is interesting about this debate is that it is a debate about the place of human beings in nature. Free will is a doctrine which is regularly envoked to show that there is a significant difference between humans and other animals. The animals are all subject to natural laws, their behavior is determined by causes. Human beings, on the other hand, operate in a sphere which is free from the determination of natural laws -- they have free will.

The first theory is that we have free will to choose between competing alternatives without our choice being determined by antecedent causes. One way of putting this is that the causes being the same, we could have chosen to do other than what we did choose to do. This is the dominant theory of free will, although there are some interesting variations on it. It holds that because we could have done otherwise we are morally and legally responsible for our acts. Because we could have done otherwise, we can rightfully be punished and rewarded for what we did.

A second theory denies that this is the case. It holds that our choices are always determined by antecedent causes, and that these antecedent causes are themselves the effects of other causes and so on ad infinitum. On this view, the idea that we have free will is labeled a delusion -- it is thinking that something is true about ourselves which is, in fact, false. This is often called hard determinism.

The third theory holds that we do have a certain kind of freedom, but it is not freedom from causes. All our choices are caused, but one must distinguish between different kinds of causes. When I am doing what I want to do, it is my own beliefs and desires and other internal factors which are causing my actions. This is quite different from my doing something because I am forced by outside causes to do something. On this view, our actions are free when the causes of our actions are internal psychological causes; are acts are not free when they are the result of external causes. The paradigm of not being free here is being in jail, and not wanting to be there. You are in your cell whether you want to be there or not.

Locke's Account of Free Will

Your problem in reading the selections from Chapter XXI provided in our text The Empiricists, is to see what Locke's theory is, and then determine its significance. Part of determining what the significance of the theory is, involves figuring out what Locke is advocating. Does he believe in free will, believe that free will is a delusion, or hold that determinism and free will are compatible?


Suppose I ask you to put an "x" in the box where you think Locke's theory belongs. How would you decide? If Locke says there is freedom, then you might be inclined to think that you should put the "x" in the FREE WILL box. But, wait, knowing that so meone believes there is freedom on action, is not enought to show that they are a FREE WILL theorist. On the other hand, suppose Locke says that free will is a nonsensical idea, because the will cannot be free. That might incline you to put the "x" in the HARD DETERMINISM box. But just knowing that someone believes that the notion of free will does not make sense, is not enough to show that that person is a HARD DETERMINIST. Here is a worksheet for you to use as you go through the chapter on "Power." When you know Locke's answers to these questions, you will then be in a position to decide which of these boxes he belongs in.

Worksheet on Free Will and Determinism

To decide the issue you need to look for a number of features in Locke's theory.

  1. Does Locke hold that human action is caused? If so what are the kinds of causes he lists?
  2. Does Locke distinguish between internal psychological causes of action and external causes? Does this distinction play a role in distinguishing between free acts and those that are not? If so, what is the distinction?
  3. Does he claim that the will is determined in its choice of action? By what?
  4. Does he say that free will is a non-sensical idea?
  5. Does he say that there is freedom? In what sense?

Understanding "Power"

How is the discussion of "free will" which occupies most of Chapter XXI connected with the idea of power? First, we have to remember that in Book II we are getting an explanation of the origins of ideas. So, in Chapter XXI Locke is explaining the origin of our idea of power. There are two classes of powers, active and passive. An active power produces a change in something else. A passive power is being capable of undergoing such a change. We might consider an origin for these ideas in either sensation or reflection. Fire has the power to melt wax. This seems like an active power. Wax has the capability to be melted, this is a passive power. Ideas of powers, Locke tells us, makes up a good deal of our ideas of substances.

In sec 4. (Pg. 42) however, we get a distinction in different kinds of powers and different kinds of substances. It is clear that we could get the idea of passive powers from material objects. But are our ideas of active powers in material substances really that clear? Locke thinks not. There are reasons to doubt that material things have a active powers. In particular active powers in sensation are motions and Locke claims that motions do not provide us with as clear and distinct ideas as do thoughts. Why? We do not get from body the beginning of motion. A ball struck by a billard stick gives us the idea of transfer not the production of motion. But an idea of a motion which does not capture the beginning of that motion is obscure. So, from sensation we only get the idea of the continuing of motion, while from reflection we get the idea of the beginning of motion.

So, if we want a clear case of an active power from which we might have got this idea, we must turn from material objects to spirit -- and the will. So, here is the connection between power and the will -- the will provides the clearest examples of the ideas of active powers.

In sec. 5 Locke explains what the Will is, and what willing and volition are. The Will is the "a power to begin or forebear, continue or end several actions of our minds and motions of our bodies, barely by a thought or preference of the mind ordering, or as it were commanding the doing or not doing or such a particular action." (Pp. 42-3). The actual exercise of this power is volition or willing. The ideas of liberty and necessity arise from a consideration of the extent of the power of the mind over one's actions.

In section 8 Locke explains what liberty is. As there are two classes of actions -- bodily movements and thoughts, "so far as a man has power to think or not to think, to move or not to move, according to the preference or direction of his own mind, so far is a man free. So, what is not being free? In the next sentence Locke tells us: "Whenever any performance or forebearance are not equally in a man's power; whenever doing or not doing will not equally follow upon his mind's directing it, there he is not free, though the action may be voluntary." ) If I don't want to do something (e.g. fall in a river) but I am compelled to do so by the bridge breaking under me, I am not free, nor is the action of falling into the river voluntary. (see sec. 9) On the other hand, if I want to do something, and it turns out that I must do it whether I want to or not, I am doing that act voluntarily (because I want to do it) but I am not free. (See sec. 10)

In sections 14 through 17 Locke discusses freedom of the will. In section 14 Locke claims that the question of whether the will is free is as absurd as asking whether a man's sleep be swift or his virtue square. Wherein lies the absurdity? The issue has to do with the nature of power. According to Locke to assert that the will is free, amounts to attributing one power, freedom, to another power, the will. But powers cannot have powers, only agents have powers. So, a person can be free, but not the will. Only agents can have powers and powers are relations and not substances and agents. In these sections you can find the answer to one of the questions on your worksheet.

In sections 25 and 29 Locke asks and answers the question of what determines the will to some particular action. His answer is that it is the mind, or the agent which determines the will. Locke continues:

What moves the mind, in every particular instance, to determine its general power of directing, to this or that particular motion or rest? To this I answer,--The motive for continuing in the same state or action, is only the present satisfaction in it; the motive to change is always some uneasiness; nothing setting us upon a change of state, or upon any new action, but some uneasiness.

So, here in sec. 29 and 48 is Locke's account of our motivation. One is moved by uneasiness of which desire is a particular species. We have many uneasinesses in us, and the general rule is that the strongest uneasiness wins. Locke hold Some goods cause us to desire them more than others. If what was really good for us were to cause us the greatest uneasiness and a slightly lesser good, a slightly lesser uneasiness and so on.we would have no problems. We would all spend out time, on Locke view, trying to gain our eternal salvation. But that is not how things work.

This is why the power to suspend the execution of actions motivated by uneasiness is so important. Reason now has a chance to review what we intend to do, and can judge whether it is for our greatest good, or if it is an attractive course of action which will lead to disaster. To engage in this activity is to use what is improperly called free will. As you will discover when you read the Second Treatise of Civil Government this means that one has the ability to follow the law of nature, even when this conflicts with ourr immediate desires.