A Brief Summary of David Hume’s logical proof of empiricism’s inherent flaw, in
his An Enquiry Concerning Human Understanding
All reasonings concerning matters of fact are founded on the relation of cause and effect
on sense impressions.
If we are to satisfy ourselves concerning the nature of that evidence by which we assume
matters of fact, then we must inquire how we arrive at the knowledge of cause and effect.
The knowledge of that cause and effect is not a priori; it comes entirely from the senses.
If we come into contact with some new object, we will not be able to discover any of its
causes or effects. We must admit that when we look at our own experience, when we
came into contact with new objects, we were not able to automatically know what caused
it or what it may cause.
The same is true for events. This is true even though we think it is not. We think that we
can infer simply from witnessing one billiard ball hitting another what would happen. But
we could not infer this a priori. The only reason we think we would know what would
happen is that we have witnessed the result before, and that conclusion has been
supported by repeated observations. Custom compels us to be firm in our belief
concerning the existence of things and causes and effects of things. “And as the first
imagination or invention of a particular effect, in all natural operations, is arbitrary,
where we consult not experience; so must we also esteem the supposed tie or connexion
between the cause and effect which binds them together and renders it impossible that
any other effect could result from the operation of that cause.”
If we were to see one billiard ball hitting another for the first time, there’s no reason why
we would not think that the second billiard ball would, say, not move, or fly straight up.
“In a word, then, every effect is a distinct event from its cause. It could not, therefore, be
discovered in the cause, and the first invention or conception of it a priori must be
entirely arbitrary. Hence the reason why no philosopher has ever pretended to assign an
ultimate cause of any natural operation, or to show distinct the action of that power which
produces any single effect in the universe.” Even though that project is one of the utmost
efforts of human reason, no philosopher has succeeded in doing so, because these
ultimate causes are “totally shut up from human curiosity and inquiry.”
When we reason a priori and consider merely any object or cause which appears to the
mind, independent of all operation, it never could suggest to us the notion of any distinct
object such as its effect, much less show us the inseparable and inviolable connection
between them.
PART 2. [THE LOGIC OF THESE ASSUMPTIONS WE MAKE IS CIRCULAR—
CAUSE-EFFECT ASSUMPTIONS ARE BASED ON EXPERIENCE ITSELF]
But we haven’t got an answer, he says, to his original question, which is what is the
nature of all reasoning concerning matters of fact. His answer: experience itself. What is
the foundation of all conclusions from experience? Experience itself. Thus there is a
circular reasoning to empirical epistemology.
Even after we have experience of the operations of cause and effect, our conclusions of
that experience are not founded on reasoning. Example: we assume bread’s nutritional
value only because we have associated qualities of a loaf of bread with its results—we
feel its nutritional effects. Those associations are repeated again and again, which
reinforces our assumptions about bread’s nutritional effect, which we think is a matter of
fact.
We think a fact is fact because we assume that fact is caused by a previous fact. We
make that assumption about cause and effect only because we commonly witness
some things or events appearing to be caused by other things or events. But there’s
no logical reason to assume that an event or thing is caused by another event or
thing; all we have to go on is experience itself.
Thus, the principle by which we assume that matters of fact are indeed matters of fact is
logically circular.
He confesses that this might appear arrogant of him to conclude that because an argument
can’t be refuted now then no argument exists to refute it. But, he says, in this case, “there
is no argument that can convince a person that an effect is a result of cause. That
understanding is only to be got by experience.”
ANOTHER VERSION OF THE SAME EXPLANATION
A CLEAR EXAMPLE OF REASONING IN A CIRCLE
The Bible tells me God exists and it doesn’t lie, b/c it was written by God; therefore, God exists. The
conclusion, that God exists, rests upon an assumption of the validity of that conclusion in
one of the premises (to have written the Bible, God must exist).
OUR ASSUMPTION ABOUT WHY THINGS EXIST (b/c they were caused):
When we assume a thing or event exists—that that thing or event is a ‘fact’—we are
assuming that ‘fact’ because we presume that something has caused that thing or event. A
table exists because someone has made it. A ball is flying through the air because someone
threw it or some prior natural event caused it to be doing so. We all exist on earth because
our biological parents somehow joined their respective sperm & egg and, voila, we sprouted.
Cause & effect is the foundation of our belief in the existence of all things and events we
experience in the world.
WHY WE MAKE THAT ASSUMPTION (custom):
We assume that events cause other events because we’ve experienced what we think is cause
& effect over and over, so we’ve become acclimated to thinking that things cause other
things and events cause other events. We believe the grass in the yard exists, and the yard
itself, b/c we assume it has been caused—either by seeding, by fencing it off from other
yards, by the formation of soil as a result of the earth’s geological history, etc.—and we
assume events cause other events because all our lives we’ve witnessed many events appear
to cause other events, so we take cause-and-effect relations for granted. Without being aware
of it, we have created a tacit epistemology.
THE FLAW IN THAT EPISTEMOLOGY (reasoning in a circle):
The only mechanism that’s compelling us to assume these cause & effect events—these
matters of ‘fact’—is experience itself. But experience was the original foundation for our
empiricist epistemology, which allowed us to assume that things exist. We make observations
of things and assume those things have been caused by other things, and then we illogically
and unthinkingly consider those observations as proof of the soundness of our
epistemology. We have reasoned in a circle. We have used our epistemology to reinforce our
belief in cause & effect relations. That tacit epistemology that we have internalized was
formed merely by experience itself. What we think is an experience of cause-effect cannot be
used logically to support an epistemology that presumes that the foundation of all
knowledge comes from experience itself. Empiricism is therefore an invalid epistemology.
THOUGHT EXPERIMENT TO SUPPORT PROOF OF THE FLAW (we could’ve
assumed otherwise):
To illustrate this fallacy, Hume argues that if I had not seen eggs in a nest, w/ my own eyes,
and seen chickens or birds occupy that nest in some way prior to or in conjunction w/ my
observation of the eggs in the nest, then there would be no reason for me not to think that
something else had caused those eggs to appear in that nest. If I had not seen billiard balls
move along the same plane on a pool table upon being struck by other billiard balls, there is
no reason I would not assume that they would, upon being struck by other balls, not move at
all, or fly up into the air.
CONCLUSION (based on reason, we don’t know anything):
Since all of our presumptions about the existence of things and events, including ourselves
and all that we have experienced, is merely based on experience itself, we have no logical
foundation to know anything. We nonetheless believe in certainty, but only b/c we’ve
adopted that belief for our own survivals. Assuming cause-effect relationships and a certain
level of certainty about the reality of our perceptions has facilitated our adoption of certain
skills that have helped us survive as a species. Hume prefigures modern cognitive science.
The down & dirty one-sentence version:
When we abstract from empiricism a cause-effect relationship among two events—which
is the basis upon which we believe an event or thing is true or real—we are begging the
question, in that our thinking that an event is a cause comes merely from experience
itself, the habitual practice of giving an event causal status merely b/c it happened near its
effect or happened before that effect time and again.