David Hume's thought and writings are
most interesting and have been extremely influential, both in the
philosophical world and in the world of the sciences, but we are going
to look briefly at only two of his ideas. These two ideas, the notion
of cause and effect, and the concept of self or identity,
are central to Hume's thought, but if you thought that Berkeley was
a tough sell, Hume's ideas may be even more difficult for you to accept.
His first book, A
Treatise of Human Nature, was published in 1738 when
he was only 27. It's a big book and quite clearly written, but no
one in the philosophical world read it. "It fell deadborn from
the press," Hume wrote some years later. Not one review was written
about that book for years after it came out. Eventually one short
review of it was published several years later in an obscure philosophical
journal, written by a philosopher no one had ever heard of. The review
said basically that the book was not so terribly written, that some
of the ideas in it were somewhat interesting, but that overall it
had obviously been written by a youthful and not-yet-mature intellect,
and that it didn't really deserve the time that it would take for
anyone to read it. That was the one published review of the Treatise.
(Only a few decades ago it was somehow
discovered that Hume himself wrote that review and submitted it to
the journal under an assumed name.)
Because that book had been such a failure
at gaining any readers, Hume decided to recast the whole of it into
a much shorter and more palatable book, An
Enquiry Concerning Human Understanding, published ten
years later in 1748 when he was 37 years old.
Hume's analysis of the notion of cause
and effect was so central to his thought that it is dealt with in
both his books, but the concept of self which was dealt with in the
Treatise was not carried over into the Enquiry. Hume
apparently believed that people would find that idea so unpalatable
that it would be best if he just left it where it was, in the Treatise.
For our purposes here we will deal first
with Hume's analysis of cause and effect, and secondly with his notion
I. Cause and effect
The idea that events are caused, i.e.,
that they do not just happen randomly, is one of the cornerstones
of our worldview. We believe that events do not "just happen,"
but that some set of causes has brought each event about. We believe
that even if we do not know what the causes are for a given event,
still some cause or causes must have brought this event into
being. Every time we ask "Why?" the appropriate response
is "Because" When we ask why something happened,
we are asking for its causes, and the reason we even ask about causes
is because we have an implicit belief that nothing happens without
This belief is one of the absolutely essential
fundamental underpinnings of our entire worldview. So fundamental
is this belief that if it were to be somehow undermined, much of our
entire worldview could suddenly become highly doubtful.
John Locke wrote about the external world's
qualities causing our sensations and perceptions, and Berkeley
wrote about God being the cause of our perceptions, so it was
natural for Hume to ask what it meant to say that one thing causes
When we say that one event causes another
- for example, flipping the light switch causes the light to go on
- we are, according to Hume, claiming that there is some "necessary
connection" between flipping the light switch and the light going
on. When we say that event A "causes" event B, we are saying
that event A and event B are not just accidentally occurring next
to each other in time, but that the two events are connected with
each other in some necessary way.
If one moment I absent-mindedly scratch
my ear and the next moment a bird smashes into my window, I'm not
likely to think those two events are causally connected. I would probably
not say that one event caused the other. I am more likely to say that
the two events - first scratching my ear and then immediately afterwards
a bird hitting the window - just happened to be immediately contiguous
with each other. We would likely say that those two events are simply
contiguous events, not necessarily connected (or causally connected)
What Hume wants us to consider here is
where our idea of cause and effect comes from. He suspects that it
may simply be an inherited idea that we've accepted without examination,
and he proposes that we examine it closely. We should look to see
if we ever actually experience cause and effect, or if it's just an
idea that was made up somewhere and we've just accepted it ever since.
So Hume asks us to look very closely at our experience to see if we
truly do experience causing going on. If we don't, that is, if the
idea has absolutely no basis in direct experience, then it should
be thrown out, as should all ideas that have no basis in experience.
Perhaps a story can help us here, a story
that is true (as best as I remember it) and is in any case highly
Thirty-five or forty years ago there was
a major power failure in New York City and all the lights in the entire
city went out. It happened late on an autumn afternoon just about
dusk, and the power failure lasted for many hours. (Exactly nine months
later all the local hospitals were literally overwhelmed with OB admissions.)
On the afternoon in question, a little four year old boy was playing
out in his front yard. On this particular afternoon, the boy was testing
his limits by venturing out toward the telephone pole at the far edge
of the front yard. His mother had always told him to never go near
the telephone pole (perhaps it was so that he would not go outside
the yard). But what he had always heard his mother say was "Never
touch the telephone pole," so of course he never had. But on
this particular afternoon his mother was not watching him quite as
closely as she normally did, and he was slowly sneaking over toward
the pole to see if maybe he could get away with touching the forbidden
pole. He finally noticed a moment when his mother was not watching
and he went over and touched the pole. And at that instant all the
lights in New York City went out.
The boy then "knew," of course,
why his mother had told him to never touch the pole. Touching the
pole had obviously caused all the lights in the city to go out. As
much as his parents consoled him later, and as much as they assured
him that his touching the pole had not caused all the lights to go
out, still he "knew" and believed that his touching the
pole had caused all the lights go out.
Now this association of two events (touching
the pole and all the lights going out) is actually much like every
other case in which we associate two events and believe that one caused
the other. What Hume would want us to do, however, is to closely examine
whether we just theorize and then believe that event A caused event
B (like the little boy did), or whether we actually experience
event A causing event B.
Hume's claim is that, like the little
boy, we do not actually experience the causing going on. All we ever
experience is that first one event occurs (touching the pole) and
then immediately following it another event occurs (the lights go
out). We never experience the first event actually doing the causing.
We never experience the "necessary connection" between the
two events. Instead, no matter how many times the two events occur
contiguously with each other, we still never directly experience any
actual causing. All we actually ever experience is events that are
"regularly contiguous" with each other. Even though we may
want to believe that one event makes another event happen,
still we never experience the making going on between the first
event and the second.
Now suppose we extend our story just a
bit further: The little boy grows up with an enormous sense of guilt
for having touched the pole, for having caused all the city's lights
to go out, and for having caused all those thousands of new births,
etc. He is distressed by this memory for years, and eventually has
to go into therapy for it. His therapist works with him for years,
all to no avail. Finally the therapist tells the young man that he
will never get over this guilt and anxiety until he again goes out
to that same telephone pole and physically touches it one more time.
Then he will see that touching the pole does not cause the lights
to go out. So he and the therapist go out to the old neighborhood,
find the exact same telephone pole, and with much fear and trembling
the young man slowly walks toward the pole. When he finally gets close
to it, with much anxiety he slowly reaches out touches the pole.
And again all the lights in New York City
go out. (The lights did actually go out a second time years later,
but I've fabricated the stuff about the boy and his therapist.) So
now the boy is absolutely convinced that touching the pole
makes the lights go out, and again he is overcome with anxiety and
guilt. We can only guess what becomes of him in the rest of his life,
but we can be sure that he never lets go of his belief that touching
the pole caused the lights to go out, no matter what rational
people tell him.
Hume believes that we are all the same
way. We continue to go on believing in the existence of cause and
effect even though no one has ever experienced causing happening,
and even though rational people (like Hume, Kant, Schopenhauer, etc)
continue to show us that the whole idea of cause and effect is merely
a theoretical construct made up in human minds. It has, these Philosophers
assure us, absolutely no basis in experience.
Now this is only a very skeletal summary
of Hume's position. The arguments which provide the foundation for
this position are spelled out very clearly in his Enquiry Concerning
Human Understanding, and are readily accessible to anyone interested
in reading them. But if Hume is correct in this assessment of the
idea of cause and effect, this is significant indeed. Many of the
sciences, for example, which have seen their primary work as "the
search for causes," would find themselves in need of re-definition
if Hume is correct.
Immanuel Kant writes, some years later,
that reading David Hume was a very powerful experience for him, and
that reading Hume's writings "woke me from my dogmatic slumbers."
Many others who read Hume find it to have the same effect on them.
What is a self, an identity, a mind, and
where does the idea of such a thing even come from? Locke believed
in the existence of minds, and so did Berkeley. Now Hume is going
to wonder what a mind, or self, is.
This question was not new even in Hume's
time. The ancients had raised the question in the following way:.
In ancient Greece there was a famous
ship tied up in the harbor so that people could come see it and
could bring their children to walk on its decks (much like today
people want to walk on the USS Missouri, or on the ship on which
their father fought in WWII, etc). This ship was famous because
it had fought in an important battle. Over the years, however, as
the ship aged, its rigging had to be replaced, and then its masts
had to be replaced. Through the years it's deck and hull planking
had all been replaced too, so that eventually every single item
on the entire ship had been replaced. There was nothing left from
the original ship. And yet during all those years and afterwards
the sign on the dock still said "This is the ship that fought
in the famous battle," and all the parents still brought their
children and told them "This is the ship that fought in the
Here's the question: Is it actually
the same ship or not? Are the parents telling their children the
truth or not? If there is not one molecule of material from the original
ship remaining because everything has been slowly replaced, should
the sign in front of it still say "This is the famous ship,"
or should it say "This is a replica of the famous ship?"
Which would you say?
If you say that it is the same ship even
though all the physical materials have been replaced, then the question
becomes: What is it that has persisted throughout all the physical
changes? You would perhaps say that the ship's "identity"
has persisted, that it is the self-same ship in its "essence,"
or its soul.
And that is a bit like the question of
self, or mind, or identity. In actuality, of course, all the molecules
in our bodies are changing all the time. Biologists tell us that all
the molecules in our bodies are completely replaced every seven years.
So are we the same "self" that we were seven years ago?
When we say "I remember when I was nine years old," we are
expressing the belief that we are essentially the same self that we
were at age nine. We have changed a lot, and have had many new experiences,
but we are still essentially the same person. I have the same parents
that that nine-year-old had, have some of the same history that that
nine-year-old had, etc. We believe we are the same person, but the
question then becomes what is the self or mind or soul that has persisted
through all the physical changes?
Hume again asks whether this concept of
self or mind is a purely theoretical construct which has no basis
in actual reality, or if it is an idea based on experience. Hume believes
that ideas not based on experience are pure fluff, have no basis in
reality, and ought to be thrown out. So is the idea of self based
on experience or not? I.e., when we turn inward to experience our
own self, or mind, do we actually experience something in there or
Hume's conclusion is that when we turn
inward what we experience in there are sensations, ideas, perceptions,
feelings, etc, but that we do not experience a "mind" or
"self" in which those ideas and perceptions reside. Here's
the way he says it.
There are some philosophers. who imagine
we are every moment intimately conscious of what we call our SELF;
that we feel its existence and its continuance in existence; and
are certain, beyond the evidence of a demonstration, both of its
perfect identity and simplicity.... from what impression cou'd this
idea be deriv'd?....
For my part, when I enter most intimately
into what I call myself, I always stumble on some particular perception
or other, of heat or cold, light or shade, love or hatred, pain
or pleasure. I never can catch myself at any time without a perception,
and never can observe any thing but the perception. When my perceptions
are remov'd for any time, as by sound sleep; so long am I insensible
of myself, and may truly be said not to exist. And were all my perceptions
remov'd by death, and cou'd I neither think, nor feel, nor see,
nor love, nor hate after the dissolution of my body, I shou'd be
entirely annihilated. (A Treatise of Human Nature, Bk I,
Hume says that since we never have any
experience of self, there is no justification for claiming that there
is any such thing.
If any one, upon serious and unprejudic'd
reflection thinks he has a different notion of himself, I must confess
I can reason no longer with him. All I can allow him is, that he
may be in the right as well as I, and that we are essentially different
in this particular. He may, perhaps, perceive something simple and
continu'd, which he calls himself; tho' I am certain there is no
such principle in me. ... (A Treatise of Human Nature, Bk
I, part vi)
So then what is actually the case, according
to Hume. What are we?
I may venture to affirm of the rest
of mankind, that they are nothing but a bundle or collection of
different perceptions, which succeed each other with an inconceivable
rapidity, and in a perpetual flux and movement....
They are the successive perceptions only, that constitute the mind;
nor have we the most distant notion of the place, where these scenes
All we are our sensations and perceptions,
says Hume. You will recall that Locke believed in four different kinds
of existents (things, perceptions, minds, and God) and that Berkeley
believed in two different kinds of existents (perceptions and minds,
God being an infinite mind). Hume believes in only one kind of existent,
namely perceptions. We usually think of perceptions as existing somehow
"inside" minds, much like furniture exists inside a living
room or beans exist inside a jar. But Hume says that what we have
done here is just made up the concept of a mind, or self, so that
we would have something for our sensations and perceptions to exist
But perhaps a self, or mind, is actually
much more like a galaxy than like a living room. A galaxy, as you
know, is not a thing inside of which there are stars, planets and
other bodies. It is the swirling stars and bodies alone which make
up the galaxy. Without the stars and bodies there would be no galaxy.
Hume is saying that the same kind of thing is true of minds. A mind
is not like a room which has perceptions inside it (even though we
may loosely speak as if that were the case). Actually, a mind is nothing
more than those perceptions simply swirling around together in a kind
of cohesive mass. That is all we are: our swirling and successive
perceptions. And "where" all this swirling is taking place,
says Hume, is a complete mystery.
If David Hume is correct about these two
fundamental concepts on which we base our worldviews, the concepts
of cause and effect and self, then much of our human thinking is based
on ideas that are purely made up and have no basis in actual experienced
Kant read David Hume and was waked from his "dogmatic
slumbers," he began his search for a way to understand the world
that could make sense both of Hume's insights and of the ways in which
we normally experience the world. The majestic effort that issued
out of Kant's struggles took form in his The
Critique of Pure Reason, and later in his Prolegomena
to Any Future Metaphysic, work that is essential for
an understanding of philosophical thought ever afterwards.