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 being caused.
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 illustrative.
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
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 famous battle."
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
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 not?
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, part vi)
Hume says that since we never have any experience
of self, there is no justification for claiming that there is any such
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 are represented.
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 in.
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
When Immanuel 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.