John Locke
1632-1704
John Locke
 a British philosopher
 Oxford academic and medical researcher
 his association with Anthony Ashley Cooper (later the
First Earl of Shaftesbury) led him to become
 a government official charged with collecting information
about trade and colonies,
 An economic writer, opposition political activist, and
 finally a revolutionary whose cause ultimately triumphed in
the Glorious Revolution of 1688.
 Much of his work is characterized by opposition to
authoritarianism.
John Locke
 This opposition is both on the level of the individual
person and on the level of institutions such as
government and church.
 For the individual, Locke wants each of us to use
reason to search after truth rather than simply accept
the opinion of authorities or be subject to superstition.
 He wants us to proportion assent to propositions to
the evidence for them.
 On the level of institutions it becomes important to
distinguish the legitimate from the illegitimate
functions of institutions and to make the
corresponding distinction for the uses of force by
these institutions.
John Locke
 The positive side of Locke's anti-authoritarianism is that
he believes that using reason to try to grasp the truth,
and determining the legitimate functions of institutions
will optimize human flourishing for the individual and
society both in respect to its material and spiritual
welfare.
 This in turn, amounts to following natural law and the
fulfillment of the divine purpose for humanity.
 Locke's monumental An Essay Concerning Human
Understanding concerns itself with determining the
limits of human understanding in respect to God, the
self, natural kinds and artifacts, as well as a variety of
different kinds of ideas.
John Locke
 It thus tells us in some detail what one can legitimately
claim to know and what one cannot.
 Locke also wrote a variety of important political,
religious and educational works including the Two
Treatises of Government, the Letters Concerning
Toleration, The Reasonableness of Christianity and
Some Thoughts Concerning Education.
An Extraordinary Time
 Locke grew up and lived through one of the most
extraordinary centuries of English political and
intellectual history.
 It was a century in which conflicts between Crown
and Parliament and the overlapping conflicts between
Protestants, Anglicans and Catholics swirled into civil
war in the 1640s.
 With the defeat and death of Charles I, there began a
great experiment in governmental institutions
including the abolishment of the monarchy, the
House of Lords and the Anglican church, and the
establishment of Oliver Cromwell's Protectorate in the
1650s.
An Extraordinary Time
 The collapse of the Protectorate after the death of
Cromwell was followed by the Restoration of Charles
II -- the return of the monarchy, the House of Lords
and the Anglican Church.
 period lasted from 1660 to 1688 and was marked by
continued conflicts between King and Parliament and
debates over religious toleration for Protestant
dissenters and Catholics.
 period ends with the Glorious Revolution of 1688 in
which James II was driven from England and
replaced by William of Orange and his wife Mary.
An Extraordinary Time
The final period during which Locke lived
involved the consolidation of power by
William and Mary, and the beginning of
William's efforts to oppose the domination of
Europe by the France of Louis XIV, which
later culminated in the military victories of
John Churchill -- the Duke of Marlborough.
Essay on Human Understanding
 Locke is often classified as the first of the great English
empiricists (ignoring the claims of Bacon and Hobbes).
 This reputation rests on Locke's greatest work, the
monumental An Essay Concerning Human Understanding.
 In writing An Essay Concerning Human Understanding
Locke adopted Descartes' ‘way of ideas’; though it is
transformed so as to become an organic part of Locke's
philosophy.
 Yet, while admiring Descartes, Locke's involvement with
the Oxford scientists gave him a perspective which made
him critical of the rationalist elements in Descartes'
philosophy.
Essay on Human Understanding
 Some philosophers before Locke had suggested that it
would be good to find the limits of the Understanding, but
what Locke does is to carry out this project in detail.
 Locke’s Essay presents a detailed, systematic philosophy
of mind and thought.
 it wrestles with fundamental questions about how we think
and perceive, and it even touches on how we express
ourselves through language, logic, and religious practices.
 In the introduction, entitled The Epistle to the Reader,
Locke describes how he became involved in his current
mode of philosophical thinking. He relates an anecdote
about a conversation with friends that made him realize
that men often suffer in their pursuit of knowledge because
they fail to determine the limits of their understanding.
Essay on Human Understanding
 In the four books of the Essay Locke considers the
sources and nature of human knowledge.
 Book I argues that we have no innate knowledge. (In this he
resembles Berkeley and Hume, and differs from Descartes and
Leibniz.) So, at birth, the human mind is a sort of blank slate on
which experience writes.
 In Book II Locke claims that ideas are the materials of knowledge
and all ideas come from experience.
 The term ‘idea,’ Locke tells us "...stands for whatsoever is the Object
of the Understanding, when a man thinks." (Essay I, 1, 8, p. 47)
 Experience is of two kinds, sensation and reflection. One of these -sensation -- tells us about things and processes in the external world.
The other -- reflection -- tells us about the operations of our own
minds. Reflection is a sort of internal sense that makes us conscious
of the mental processes we are engaged in. Some ideas we get only
from sensation, some only from reflection and some from both. Locke
has an atomic or perhaps more accurately a corpuscular theory of
ideas
Essay on Human Understanding
 Ideas are either simple or complex. We cannot create simple
ideas, we can only get them from experience. In this respect the
mind is passive. Once the mind has a store of simple ideas, it can
combine them into complex ideas of a variety of kinds. In this
respect the mind is active.
 Thus, Locke subscribes to a version of the empiricist
axiom that there is nothing in the intellect that was not
previously in the senses -- where the senses are
broadened to include reflection.
 Book III deals with the nature of language, its connections
with ideas and its role in knowledge. Book IV, the
culmination of the previous reflections, explains the nature
and limits of knowledge, probability, and the relation of
reason and faith
Essay on Human Understanding
 the relationships among perception, thought, and
language. As opposed to accepting the possibility of
directly receiving truth, he sees physical science as
moving toward truth, but knowledge as psychology.
 Outside world--sense perception--ideas--knowledge of
ideas--reflection upon those ideas--ideas as signs of real
things and words as again removed.
 Book III deals with the nature of language, its connections
with ideas and its role in knowledge.
 Book IV, the culmination of the previous reflections,
explains the nature and limits of knowledge, probability,
and the relation of reason and faith
Book I
 In Book I, Locke lays out the three goals of his
philosophical project:
 to discover where our ideas come from,
 to ascertain what it means to have these ideas and what an idea
essentially is, and
 to examine issues of faith and opinion to determine how we should
proceed logically when our knowledge is limited.
 He attacks previous schools of philosophy, such as those
of Plato and Descartes, that maintain a belief in a priori, or
innate, knowledge.
 begins by opposing the idea that we are all born knowing
certain fundamental principles, such as “whatever is, is.”
 The usual justification for this belief in innate principles is
that certain principles exist to which all human beings
universally assent.
Book I
 Locke contends that, on the contrary, no principle is
actually accepted by every human being.
 Furthermore, if universal agreement did exist about
something, this agreement might have come about in a
way other than through innate knowledge.
 Locke offers another argument against innate knowledge,
asserting that human beings cannot have ideas in their
minds of which they are not aware, so that people cannot
be said to possess even the most basic principles until
they are taught them or think them through for themselves.
 Still another argument is that because human beings differ
greatly in their moral ideas, moral knowledge must not be
innate.
Book I
 Finally, Locke confronts the theory of innate ideas (along
the lines of the Platonic Theory of Forms) and argues that
ideas often cited as innate are so complex and confusing
that much schooling and thought are required to grasp
their meaning.
 Against the claim that God is an innate idea, Locke
counters that God is not a universally accepted idea and
that his existence cannot therefore be innate human
knowledge.
Book II
 Having eliminated the possibility of innate knowledge,
Locke in Book II seeks to demonstrate where
knowledge comes from.
 He proposes that knowledge is built up from ideas,
either simple or complex.
 Simple ideas combine in various ways to form
complex ideas.
 Therefore, the most basic units of knowledge are
simple ideas, which come exclusively through
experience.
Book II
 There are two types of experience that allow a simple
idea to form in the human mind:
 sensation, or when the mind experiences the world outside
the body through the five senses, and reflection, or when the
mind turns inward, recognizing ideas about its own functions,
such as thinking, willing, believing, and doubting.
 Locke divides simple ideas into four categories:
 ideas we get from a single sense, such as sight or taste;
 ideas created from more than one sense, such as shape and
size;
 ideas emerging from reflection; and
 ideas arising from a combination of sensation and reflection,
such as unity, existence, pleasure, pain, and substance.
Book II
 Locke goes on to explain the difference between
primary and secondary qualities.
 Ideas of primary qualities—such as texture, number, size,
shape, and motion—resemble their causes.
 Ideas of secondary qualities do not resemble their causes,
as is the case with color, sound, taste, and odor.
 In other words, primary qualities cannot be separated from
the matter, whereas secondary qualities are only the power
of an object to produce the idea of that quality in our minds.
Book II
Locke devotes much of book II to exploring
various things that our minds are capable of,
including making judgments about our own
perceptions to refine our ideas, remembering
ideas, discerning between ideas, comparing
ideas to one another, composing a complex
idea from two or more simple ideas, enlarging
a simple idea into a complex idea by
repetition, and abstracting certain simple
ideas from an already complex ideas.
Book II
 Locke also discusses complex ideas, breaking them
down into four basic types:
 modes, which are ideas that do not exist in and of
themselves, such as qualities, numbers, and other abstract
concepts;
 substances, either self-subsisting things (such as a
particular man or a sheep) or collections of such things (an
army of men or a flock of sheep);
 relations, such as father, bigger, and morally good; and
 abstract generals, such as “man” or “sheep” in general.
Complex ideas are created through three methods:
combination, comparison, and abstraction.
Book III
 In book III, Locke discusses abstract general ideas.
 Everything that exists in the world is a particular “thing.”
 General ideas occur when we group similar particular
ideas and take away, or abstract, the differences until we
are left only with the similarities.
 We then use these similarities to create a general term,
such as “tree,” which is also a general idea.
 We form abstract general ideas for three reasons:
 it would be too hard to remember a different word for every
particular thing that exists,
 having a different word for everything that exists would obstruct
communication, and
 the goal of science is to generalize and categorize everything.
Book III
 There is a clear connection between Book II and III in that
Locke claims that words stand for ideas.
 Locke argues against the notion of essences, a concept
that had been widely accepted since at least Plato’s time.
 Plato argued that we can only recognize individuals as
members of a species because we are aware of the
essence of that species—for example, we recognize a
particular tree as a tree because we understand what a
tree is in its essence.
 Locke argues that essences don’t actually exist as ideal
entities but are instead nothing more than the abstract,
general ideas that we form about the things we observe,
things that actually exist in the world.
Book III
 Human beings decide which differences and similarities they will
use to separate and classify particular things into categories—
they choose how to define categories rather than discovering
the essence of a given species.
 Despite having just criticized the traditional concept
of essences, Locke decides to adopt the term into his
own philosophy and proceeds to distinguish between
real essences and nominal essences.
 Nominal essences are the specific collections of observable
properties from which we create an abstract general idea.
For example, we observe similarities between many different
individual dogs and from these observations form our idea of
what a dog is.
Book III
 Real essences are the invisible structures and arrangements of
corpuscles or atoms that allow for those observable properties to
be observable in the first place. For example, to return to the case
of dogs, if we could fully understand the biological structures and
processes that make a dog a dog, whether those would include
DNA or other things as well, then we would understand the real
essence of dogs. Unlike the nominal essence, the real essence has
a basis in reality.
 Locke moves on to discuss language, pointing out
natural weaknesses and common abuses of
language. The most significant problem with words is
that they do not immediately and obviously mean the
same thing to all people.
Book III
 This problem has four main causes:
 a word may imply a very complex idea,
 the ideas that words stand for may have no constant
standard anywhere in nature to judge them against,
 the standard that ideas refer to may not be easily known,
and
 the meaning of a word and the real nature of the thing
referred to by the word may not be exactly the same.
 Locke also identifies six common abuses:
 people often use words without really knowing what these
words mean,
 people use words inconsistently,
Book III
 Locke also identifies six common abuses:
 people purposefully make terms obscure by using old words for new and
unusual uses or by introducing new terms without defining them,
 people mistakenly believe that words refer to things rather than ideas,
 people try to use words incorrectly to change their meaning, and
 people assume that others know what they are saying when they are not
really being clear.
 Locke suggests four remedies to counteract the natural shortcomings
and the abuses of language:
 never use a word without having a clear idea of what it means;
 try to recognize the same meaning for words as others do so that we can
communicate with a common vocabulary;
 if there is the slightest chance that the meaning of your words will be
unclear, define your terms; and
 always use words consistently.
Book IV
In book IV, Locke addresses the nature of
knowledge itself, asking what knowledge is
and in what areas we can hope to attain it.
For Locke, knowledge is what the mind is
able to perceive through reasoning out the
connection, or lack of connection, between
any two or more of our ideas.
Because knowledge only has to do with
relations between ideas, which are in the
mind, the knowledge we are capable of is not
actually knowledge of the world itself.
Book IV
 Locke identifies four sorts of agreement and
disagreement that reason can perceive to produce
knowledge:
 identity (blue is blue) and diversity (blue is not yellow),
 relation (two triangles with equal bases located between the
same two parallel lines are equal triangles),
 coexistence (iron is always susceptible to magnets), and
 realization that existence belongs to the ideas themselves
and is not in the mind (the idea of God and of the self).
 Locke distinguishes between three grades or degrees
of knowledge:
 intuition, when we immediately perceive an agreement or
disagreement the moment the ideas are understood;
 demonstration, which requires some sort of proof; and
sensitive knowledge, which is about the existence of an
external world, roughly resembling the world as we perceive
Book IV
 Locke argues that we can never really develop a
system of knowledge in natural philosophy.
 The best that we can do is to observe certain
qualities in the world that tend to occur together on a
regular basis.
 The kind of connection he demands is the sort that
we find between properties occurring together
regularly in geometrical figures.
 Although he doesn’t seem to think we will ever be
able to know more about the true nature of things,
 Locke is hopeful that we can understand existence,
and the properties of things that exist in the world,
much more thoroughly.
Book IV
 Locke outlines three strategies for dealing with
the problem of skepticism, or doubt about
whether the world exists outside of our minds.
 This problem arises naturally from Locke’s
theory of knowledge.
 If we only have access to the ideas in our
minds, which only exist in our minds, how do
we know there is a real world outside of our
minds?
 Locke’s first strategy is to refuse to take the
skeptic seriously.
 Can anyone really doubt, he asks, that there is an
external world out there?
Book IV
 His second strategy is to say that it doesn’t matter
whether we doubt the existence of an outside world or
not.
 All that matters is that we know enough to enable us to
get around in the world.
 His third line of attack involves seven marks of our
experience that can best be explained by the
existence of an external world:
 there is a certain realness and strength of clarity to
perception of an immediate object that memories or products
of the imagination do not have,
 we cannot get these ideas without the sense organ
appropriate to them,
 we are able to receive ideas of this sort only in certain
situations so it cannot be the organs themselves that are
responsible for producing the ideas,
Book IV
 we receive ideas passively,
 some ideas are accompanied by pleasure or pain but the
memories of those ideas are not,
 our senses often bear witness to the truth of each other’s
reports, and
 two different people can share the same experience.
 Locke argues that almost all of science, with the
exception of mathematics and morality, and most of
our everyday experience is subject to opinion or
judgment.
 We base our judgments on the similarity between
propositions to our own experience and to the
experiences we have heard described by others.
Book IV
 Locke examines the relation between reason and faith.
 He defines reason as being the faculty we use to
obtain judgment and knowledge.
 Faith is the acceptance of revelation and has its own
truths, which reason cannot discover.
 Reason, however, must always be used to determine
which revelations truly are revelations from God and
which are the constructions of man.
 Finally, Locke divides all of human understanding into
three sciences: natural philosophy, or the study of
things to gain knowledge; ethics, or the study of how it
is best to act; and logic, or the study of words and
signs.
Locke’s Contribution
 Locke effectively shifted the focus of seventeenthcentury philosophy from metaphysics to the more
basic problems of epistemology, or how people are
able to acquire knowledge and understanding.
 Locke rigorously addresses many different aspects of
human understanding and of the mind’s functions.
 His most striking innovation in this regard is his
rejection of the theory that human beings are born
possessing innate knowledge, which philosophers
such as Plato and Descartes had sought to prove.
Locke’s Contribution
 Locke replaces the theory of innate knowledge with his
own signature concept, the tabula rasa, or blank slate.
 Locke tries to demonstrate that we are born with no
knowledge whatsoever— we are all blank slates at
birth—and that we can only know that things exist if
we first experience them.
 Locke presents “simple” ideas as a basic unit of
human understanding, claiming that we can break all
of our experiences down into these simple,
fundamental parts that cannot be broken down any
further.
Locke’s Contribution
 For example, the idea of a plain wooden chair can be
broken down into simpler units that are received by
our minds through one sense, through multiple
senses, through reflection, or through a combination of
sensation and reflection.
 “Chair” is thus perceived and understood by us in
several ways: as brown, as hard, as according to its
function (to be sat upon), and as a certain shape that
is unique to the object “chair.”
 These simple ideas allow us to understand what
“chair” is and to recognize it when we come in contact
with it.
Locke’s Contribution
 Locke’s theory of primary and secondary qualities is
based on the Corpuscular Hypothesis of Robert Boyle,
Locke’s friend and contemporary.
 According to the Corpuscular Hypothesis, which Locke
considered the best scientific picture of the world in his
day, all matter is composed of tiny particles, or
corpuscles, which are too small to see individually and
which are colorless, tasteless, soundless, and
odorless.
 The arrangement of these invisible particles of matter
gives an object of perception both its primary and
secondary qualities.
 An object’s primary qualities include its size, shape,
and movement.
Locke’s Contribution
 They are primary in the sense that these qualities exist
regardless of whether anyone perceives them.
 Secondary qualities include color, odor, and taste, and
they are secondary in the sense that they may be
perceived by observers of the object, but they are not
inherent in the object.
 For example, a rose’s shape and the way it grows are
primary because they exist regardless of whether they
are observed, but the rose’s redness only exists for an
observer under the right conditions of lighting and if
the observer’s eyesight is functioning normally.
 Locke suggests that because we can explain
everything using the existence only of corpuscles and
primary qualities, we have no reason to think that
secondary qualities have any real basis in the world.
Locke’s Contribution
 According to Locke, every idea is an object of some
action of perception and thinking.
 An idea is an immediate object of our thoughts,
something we perceive and to which we are actively
paying attention.
 We also perceive some things without ever thinking
about them, and these things do not continue to exist
in our minds because we have no reason to think
about them or remember them.
 The latter are nonimmediate objects. When we
perceive an object’s secondary qualities, we are
actually perceiving something that does not exist
outside of our minds.
Locke’s Contribution
 In each of these cases, Locke would maintain that the
act of perception always has an internal object—the
thing that is perceived exists in our mind.
 Moreover, the object of perception sometimes exists
only in our minds.
 One of the more confusing aspects of Locke’s
discussion is the fact that perception and thinking are
sometimes, but not always, the same action.
 To add to the confusion, Locke claims in Book II that
an action of perception may have a nonimmediate
object, not that it must have one.
 This makes it difficult to pin down a rule for what
perception is and isn’t, and how perception works.
Locke’s Contribution
 We may find Locke’s discussion of essence, or
substance, confusing because Locke himself doesn’t
seem convinced of its existence.
 Locke may have chosen to retain this concept for
several possible reasons.
 First, he seems to think that the idea of essence is
necessary to make sense of our language.
 Second, the concept of essence solves the problem of
persistence through change: that is, if a tree is just a
bundle of ideas such as “tall,” “green,” “leaves,” and so
on, what happens when a tree is short and leafless?
Locke’s Contribution
 Does this new collection of qualities change the
essence from “tree” to something new?
 In Locke’s view, the essence persists through any
change, remaining the same despite changes in the
object’s properties.
 A third reason Locke seem to be compelled to accept
the notion of essence is to explain what unifies ideas
that occur at the same time, making them into a single
thing, distinct from any other thing.
 Essence helps clarify this unity, though Locke is not
very specific about how this works.
 For Locke, essence is what qualities are dependent on
and exist in.
Locke’s Contribution
 Locke’s view that our knowledge is much more limited
than was previously supposed was shared by other
seventeenth- and eighteenth-century thinkers such as
Descartes and Hume—even though Locke differs
sharply from Descartes about why that knowledge is
limited.
 For Locke, however, the fact that our knowledge is
limited is a philosophical rather than practical matter.
 Locke points out that the very fact that we do not take
such skeptical doubts about the existence of the
external world seriously is a sign of how
overwhelmingly probable we feel the existence of the
world to be.
Locke’s Contribution
The overwhelming clarity of the idea of an
external world, and the fact that it is confirmed
by everybody except madmen, is important to
Locke in and of itself.
Even so, Locke holds that we can never have
real knowledge when it comes to natural
science.
Rather than encouraging us to stop bothering
with science, Locke seems to say instead that
we should be aware of its limitations.