Download Lecture Introduction to John Locke

Lecture
Introduction to John Locke
(1632-1704, age 72)
An Essay Concerning Human Understanding
(published in 1690, at age 58)
(This lecture is a longish one; you may want to print it out for reading)
John Locke is really a very clear and sensible writer, as you would soon see yourself if you had
the time to go look at his Essay Concerning Human Understanding or any other of his
philosophical writings. But the Essay is also very lengthy, so I've not assigned you to read any of
it this quarter. Instead, I'm going to just tell you a few of the main points he makes in that book.
So after some introductory words, the following mini-lecture will be divided into eight of the key
points Locke would most like you to learn from his book.
Introduction
In his youth Locke seriously intended to enter the seminary to become a priest, but in the end he
chose to study medicine instead. He became a physician, but practiced only a little, devoting
most of his time to writing and official duties.
Locke considers epistemology to be "first philosophy," because he considers it to be the
discipline that examines the instrument that does the knowing and philosophizing, viz., the
human mind. When you take a biology course, your first lab will be to study and understand the
microscope, because the microscope is such a crucial instrument in learning about biology. In a
similar way, philosophy's first task should be to examine how the human mind knows anything,
which is the task of epistemology. And the first task of epistemology should be to find out if the
mind is even capable of knowing anything, and if it is, what are the limits to what it can know.
In his epistemological studies, as we will see below, Locke relies much more heavily on direct
sensory experience than on logic and reason. He believes direct experience to be a more reliable
source of knowledge than logic and reason. Descartes, a philosopher in the rationalist tradition,
chose to rely more on reason and logic for his analyses, but Locke is, after all, a physician.
Physicians rely on evidence they get from their patients, they form hypotheses as to what might
be the underlying problem with their patient, and they attempt treatments. If the treatments don't
work they form another hypothesis and attempt another treatment, and so on. Absolute certitude
may be something mathematicians can hope for, but the physician must rely on experience and
testing. Locke believes that is also how we derive our knowledge about the world.
In any case, following are some of the key points to learn from Locke's Essay.
I. There are no innate ideas
Locke spends the entirety of Book I in his Essay arguing that human beings have no inborn, or
innate, ideas in their minds at birth. Some of the rationalist philosophers wanted to claim that
when a human mind comes into the world it already understands such fundamental principles as
the principle of non-contradiction - that a thing cannot both be and not be at the same time in the
same respect - and the principle that the whole is more than the part. Locke does not believe that
we are born with any of these inborn ideas.
Locke believes that when a human mind is first born - whether the birth of that human mind be
dated at the moment of parturition (birth), or earlier at the moment of conception, or at some
point in between - when the human mind first comes into existence it does not come with any
inborn ideas. When it first exists it is a blank slate, a "tabula rasa," an empty surface on which
experience will then subsequently write all that we ever know. We may be born with automatic
instinctual behaviors - such as automatic reflex motions in response to some stimulus - but these
are not ideas or perceptions or what today we might call "contents of consciousness."
II. All ideas come from experience
All contents of consciousness, that is, everything that ever gets into the mind, comes into it from
one source only, and that source is experience. Experience is the one source of input into the
human mind.
There are two kinds of experience, for Locke.
a. Experience of the outer world, which he terms sensation, and from this mode of experience
we derive such notions as blue, round, solid, smooth, heavy, large, etc.
b. Experience of the inner world, which Locke terms reflection, and from this mode we get such
notions as fear, love, willing, doubting, affirming, thinking, feeling, believing, remembering,
planning, anticipating, and so on.
For Locke, the term "idea" is rather a technical term. By "idea" he means anything that exists in
consciousness, i.e., anything that exists in the mind.
So to sum up these first two points, no ideas are inborn in the mind; instead, all ideas, that is, all
contents of the mind, come to us ultimately from only one source, experience (either sensation or
reflection).
III. Simple and complex ideas
There are basically two sorts of ideas, simple and complex. Simple ideas include all our simple
sensory sensations such as red, cold, sweet, loud, soft, round, etc.
Complex ideas are complexes of simple ideas. For example, my sensory experience of a red ball
would include a mixture of the simple ideas of red, round, hard, cool, etc. That complex of
simple sensations goes into making up my experience of the ball. That is to say, the sensation of
this red ball that is in my mind right now, i.e., the "idea" of the ball, derives from the sensory
experience of the ball that I am presently experiencing.
In all his thinking about how knowing works, Locke sees himself as following a very common
sense way of thinking. He does not see himself as saying anything particularly abstruse or
unusual, and certainly not as saying anything that every common sense person wouldn't agree
with. In this next section, though, at least toward the end of it, based on common sense though it
is, we might at first think he is saying something that common sense should not accept. But you
might want to reserve your judgment on that for a while.
IV. Ideas are caused in us by qualities
Ideas (or sensations) in minds are caused by qualities in things. For example, the sensation (or
idea) of red in my mind is caused by the quality of red in the thing.
So we now need a definition of what a quality is. Here it is: A quality is a power in a thing to
cause an idea in a mind. So a quality is not a thing, really, but is a power in a thing to cause an
idea in a mind.
Now this is where it gets interesting. There are two kinds of qualities, according to Locke,
primary and secondary. (He actually says there are three kinds of qualities, but we're going to
ignore the third kind for now.)
Primary qualities are those that every physical object, every body, must have. Primary qualities
are actually in the physical object. There are only six primary qualities:
solidity (bulk)
figure (shape)
extension (size)
motion/rest
number
texture
Every physical object, in order to even be a physical object, must (according to Locke) have
solidity, must have some shape and size, must be either in motion or at rest, must be either one or
many, and must have some texture.
Secondary qualities, on the other hand, are nothing but powers in things to produce a sensation
in a mind. Now this is an idea that we will need to explore in a bit more detail.
Let's consider the old philosophical question: When a tree falls in the forest and there is no one
around to hear it (i.e., no ears of any sort, no squirrels, reindeer, frogs, lemurs or pachyderms),
does it make a sound?
Locke's answer would be this. A sound is a sensation in a mind. So "sound" is the kind of
existent that exists inside minds, not out in forests. Now the sensation of sound in a mind is
caused by a quality out in the world, so let's examine what quality is out there in the world that
would cause that sound sensation in your mind.
When a tree falls, it is passing through a medium (air), and in the process of passing through that
medium, it causes impact waves in that medium. See the illustration below.
(note: No graphic artists were harmed or mistreated in the production of this image, and the
illustration is definitely not drawn to scale.)
Here's what's happening: In the act of falling, the tree passes through a medium (air), and in the
process sets up impact waves which move through that medium (much like dropping a pebble in
a pool of water causes waves to ripple outward in the medium of water). The impact waves are
not themselves sound, but if they strike an auditory apparatus of some sort (like an eardrumauditory nerve-brain combination) then those waves can cause the sensation of sound ("Boom
and Crash") in those brains. So the sound is clearly inside the brain, and what is outside in the
world is a quality that has the power to cause a sensation of sound in a brain.
So if there are no brains or hearing apparatuses around, then there are no sounds. In fact, if a tree
falls in the forest and there are people there, there is still no sound in the forest. The sound is
always in the sensorium of the experiencing brain, not out there in the world. What is out there in
the world are impact waves in a medium. Those waves are not themselves sound, but they can
cause sound if they impact a hearing apparatus (like the ones for squirrels, lemurs, pachyderms
humans, and others).
So sound is never "out there," no matter what sound we're talking about. It is always in a mind.
What is out there is some sort of quality which has the power to cause a sensation in a mind.
What Locke would have us notice here is how completely different the impact waves out there in
the world are from the sound sensation that exists in a mind. These two realities are totally
different kinds of entities. Impact waves are out there moving through air. Sound is a sensation
that happens in a mind. Very different kinds of realities.
The concept of the transducer might help us here. Locke did not have transducers around when
he was writing, but if he had, he would have loved the idea. A transducer is something in the
world of electronics. A transducer is basically any electrical device that changes, or transduces,
one form of energy into another form of energy.
A lightbulb, for example, is a transducer. It changes simple electricity (which is not visible) into
visible light. It is important to notice here that what goes into the lightbulb (electricity) is not at
all the same thing that comes out of it (light). A very naïve person who saw an electric cord
leading into the lightbulb might wrongly guess that the cord carried light into the lightbulb. That
would be naïve and wrong, of course. In much the same way, what is impacting onto our hearing
apparatus is a series of moving waves in a medium. The impact of those waves on our eardrum,
and then on into the inner ear, the auditory nerve, and so on, then transduces all that input into a
sound. And what Locke would have us notice is that a sound sensation is a very different kind of
animal than an impact wave in a medium.
A radio receiver is another example of a transducer. It takes radio-frequency (RF) waves passing
through space and transduces them into something we can hear. The RF waves are not
themselves hearable until they have been transduced by the receiver.
Our visual apparatus is also a kind of transducer. Light waves come streaming into our eye and
impact on the surface of the retina. From that point on our visual apparatus (retina, rods & cones,
optical nerve, brain, etc) transduces those light waves into a sensory experience with color,
shape, size, etc.
Now we sometimes assume that when any two of us look toward the same object, we must each
also be having the same sensory experience. That is, we assume that we each transduce those
light waves into the same visual experience. We might even assume that if my dog and I look
toward the same object that we will both see the same thing. Or that a lizard and I would see the
same thing. But the fact is that different organisms, i.e., different visual apparatuses, in fact
transduce things quite differently than humans do.
Many years ago I saw a nice layout in a magazine (unfortunately this was so many years ago - I
think I was still in college - that I no longer recall the magazine or date) which showed an array
of photographs taken of a single daisy. The interesting thing was that each photograph was taken
through the visual apparatus of a different animal. I believe the photographer may have been
Lennart Nilsson, or at least was a photographer who used lasers in his photography, and the
photographer was able to somehow get the camera to "see" the daisy through the visual apparatus
of several different animals. There was a photo of the daisy as seen through the eye of a dog, a
lizard, a housefly, and so on. What was interesting was how astonishingly different the daisy
appeared through the visual apparatus of those different organisms. In some it was colored
certain ways, in others it was colored other ways, in some it was shades of gray with no other
colors, in some the shape appeared nothing like a daisy, in some the image was multiplied, and
so on. In some cases it appeared so different as to not even be recognizable as a daisy.
It was actually a two-page layout, with these dozen or so images laid out on the left side of the
display. Then on the right side of the display was a full page photo of the daisy as seen through
the human visual apparatus. The implication of the layout seemed to be, since the photo of the
daisy as seen by a human was so much larger, that "This is the way the daisy truly appears, viz.,
the way it is seen by humans." But of course that implication would not be accurate. The photo
of the daisy as seen through the human eyes should have been no larger than the photos through
the eyes of all the other organisms.
In any case, that photo layout really brought home to me that we all transduce the stimuli that
come into us so that it will register in our brain in categories that our brain is designed to
understand. And that every other organism does the same thing.
Now let's bring this back to John Locke and his notion of secondary qualities. This notion that
our brains transduce the stimuli that come into them is exactly what Locke meant when he said
that secondary qualities are nothing but powers in a thing to produce sensations in a mind.
So Locke's notion is that everything we perceive besides the six primary qualities (solidity, size,
shape, texture, number, and motion/rest) are all secondary qualities. They aren't really out there
in the world in the way we think they are. Sound isn't really out there in the world in the way we
think it is. Nor is color. Nor is temperature, taste, smell, and so on. Neither are other sensations,
like pain, for example. We all realize that the pain we experience is not actually out there in the
world. We realize that pain is a sensation we have in our brain/mind and that it is caused by
something out there in the world (a needle, a burn, etc) which is not itself pain. It is just the cause
of pain. We know the same thing about the sensation of tickle, that it is not out there in the
world. There may be a feather out there in the world that some cruel person is maliciously
applying to us, but we realize that the tickle is purely a sensation that exists in our mind (or
brain). Well, Locke just wants us to realize that all our other sensations (except the six primary
qualities) are also just in our minds.
V. Judgment constantly alters our perception
This fifth point is simply that there is a crucial difference between "sensation" and "perception"
(to put this in contemporary terms). Sensation is simply the raw data that your senses bring into
your brain, and perception includes the judgments and interpretations that you add to the
sensations so that it ends up having some meaning for you.
Perhaps an example will make this clear.
I once went with a friend to the Chicago Art Institute and on the second floor was an enormous
painting which took up one entire wall. It reached clear up to the ceiling and all the way down to
the floor. It was an amazingly realistic and full-size painting of a hallway in an art museum, so as
you stood looking at it, you had the impression you were looking down a hallway which then
opened into another room of the art gallery. You could see some paintings hanging on the wall in
the hallway, and one or two people standing looking at them. It was all very realistic, and since it
took up an entire wall, with no noticeable frame around it, you could easily believe that you were
looking at an actual hallway.
Well, the Art Institute had to put a big piece of plexiglas up in front of this painting because
people kept walking into it and bumping it.
The people who walked into the painting were having certain raw sensations when they saw the
large painting (simple two-dimensional shapes of various sizes, etc on a flat wall), and to those
raw two-dimensional sensations they added certain non-conscious judgments and interpretations
about what those shapes and sizes meant. They thus interpreted the two-dimensional shapes to
have three-dimensional meanings. They interpreted the lines and colors they saw on the wall to
mean that there was open space in front of them.
According to Locke (and to most contemporary sensory psychology too), we do this all the time
in all our perceptions. We receive only the raw sensation, but we always overlay that raw
sensation with our non-conscious judgments and interpretations, and then what result from that
are our perceptions. So the formula would look like this:
sensation + judgment = perception
Or raw sensation, plus how we construe those sensations, yields what our minds then perceive.
VI. Naive realism vs critical realism
Locke's next point is the distinction between naïve realism and critical realism.
First, though, we must distinguish between the philosophy of realism and the philosophy of
idealism. Realism is any philosophy which holds that there is a real world out there, and that our
sensations and perceptions result from an encounter with that real world. Idealism (as you would
seen in George Berkeley if you read him) is any philosophy which holds that there is no real
world out there, and that the only things that exist are our perceptions and sensations.
Locke is definitely a realist. He believes that there is a real world out there, and he believes that's
what good common sense teaches us too. But Locke wants to distinguish between a naïve
realism and a critical realism. Naïve realism would be the unreflective belief that there is a real
world out there, and that our perceptions are an exact copy, an exact replica, of what is actually
out there in the world. Naïve realism thinks of our senses as more or less like a simple brownie
camera, in which we open our senses to the world and the world comes simply streaming into
our mind and leaves a perfect copy of itself in our perceptions. Naïve realism would not be aware
of how much our senses and brain transduce the information that comes into them.
Locke considers himself to be a critical realist. Critical realism is the belief that yes, there is a
real world out there, but our sensations and perceptions are not simple copies of that real world.
Critical realism believes that our senses really do transduce and modify the incoming data so that
it will register in our minds in ways that make sense to our brains and minds.
Perhaps a metaphor can help this more understandable.
Suppose a classroom full of little laptop binary computers all sitting in a circle and having a
discussion amongst themselves. All any of them can perceive, of course, are ones and zeros,
since they are all binary computers and that is all that binary computers can perceive. (If we want
to communicate with our computers, you know that we must translate everything we want to say
to them into ones and zeros; so if I want to say "L" to my computer, I have to translate that L into
10001010 so that the computer can understand it, because strings of ones and zeros are all that its
little processor can register.)
In any case, imagine all these little computers thinking about what the real world out there must
actually be like. The naïve realists among them would believe that the world consists of nothing
but ones and zeros, because that is exactly what they all see. The critical realists among them
would believe that yes, there must be a real world out there, but it probably does not consist of
only ones and zeros. "The world comes streaming into us through our input devices," says one
critical realist computer," but our input devices transduce the world into the categories that we
can understand, which is ones and zeros. The world out there is not actually ones and zeros, but
ones and zeros are the only categories we have for perceiving the world, so if we're going to see
anything at all, it will have to register with us in those categories."
Locke believes that we are just like the binary computers, except that we have a few more
categories of perception than they do. (Later we will see that Immanuel Kant believes that we
have twelve or fourteen categories of perception.)
To sum up, naive realism believes there is an isomorphic relationship between what we perceive
and what is actually out there in the world. You don't have to learn much sensory psychology,
though, before you discover that Locke's critical realism is probably a lot closer to the mark
VII. Four kinds of existents
Locke believes that there are only four kinds of realities (existents) that exist in the world.
1. He believes there are selves (or minds). He believes that we know about the existence of
minds both our own and those of other people -- by a process he terms "intuiting."
2. The second kind of existent Locke calls ideas, i.e., the contents of minds. He believes we
know about the existence of ideas by reflection.
3. The third kind of existent is things, or physical objects. Locke believes that we know about
the existence of things through sensation.
4. Fourthly, Locke believes that there is a God, and that we know about God's existence by
logical proofs for his existence. (We will not be looking at any of the classical arguments for the
existence of God, but if you ever take a Philosophy of Religion course you will learn about them
there.)
VIII. Two big questions
Finally, there are two key questions Locke considers it important to ask, and it may even be that
the asking of these two questions is more important than the specific answers Locke gives to
them.
1. The first question is this: Can we know that things continue to exist during the intervals that
they are not being observed by anyone? For example, imagine that you are perceiving the mug
on your desk, but that you then turn away from it so that you are no longer perceiving it in any
way (and neither is anyone else). You do not see it, feel it, hear it, smell it, or perceive it in any
way (and neither does anyone else). Then you turn back and perceive it again. Then you turn
away and are no longer perceiving it. The question is this: during the intervals that the mug is not
being perceived, can we know that it continues to exist during those intervals?
This may seem like a silly question, but when one is doing epistemology it is important to
examine closely the assumptions that are made about what it is possible to know. And Locke is
willing to examine this assumption we all seem to have, that things somehow continue in
existence even though no one is perceiving them. So that's question number one.
2. The second question is this: Even during the times that we are directly observing an object can
we know for sure that the object actually exists.
Now the answers that Locke himself proposed for these questions are not nearly as important as
the fact that he posed the questions. The next two philosophers who follow Locke in the
empiricist tradition - George Berkeley and David Hume - take these two questions very seriously
and suggest answers very different from those that Locke offered.
Just for the record, though it is not particularly important for our purposes here, here are the
answers that Locke proposed for these two questions.
1. Can we know that objects continue to exist even when they are not being perceived by
anyone? Answer: Well, perhaps we cannot be absolutely certain of their continued existence
during the times when they are not being perceived, but common sense tells us that in all
probability they do continue to exist even when not being perceived.
2. And can we know that objects exist even when they are being perceived? Locke's answer:
Surely no one would be so skeptical as to hold that we cannot know objects exist when they are
being directly perceived. Common sense tells us that of course we can know that objects exist
during the intervals that we are directly perceiving them.
You might now ask yourself whether you think Locke's answers to these two questions should be
considered adequate or not.
George Berkeley, while he greatly admired Locke and his work, did not consider that Locke had
carried his epistemological examinations quite far enough. I sometimes wonder if Berkeley may
have thought that Locke lost a bit of his question-asking courage here when he caved in to toosimple answers to these two questions.
So one of the big questions Berkeley takes up when he writes both his Principles of Human
Knowledge and his Three Dialogues Between Hylas and Philonous is the even more central
question: What does "to exist" actually mean? We may assume that we understand this simple
word which we use so easily and frequently, but what exactly are we claiming when we claim
that a thing "exists?"
Berkeley's answer to this question is a most interesting one.