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An Enquiry Concerning Human Understanding. (1748)

Sect. IX. Of the Reason of Animals

David Hume.

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An Enquiry Concerning Human Understanding.

David Hume.

Sect. IX. Of the Reason of Animals

  82. ALL our reasonings concerning matter of fact are founded on a
species of Analogy, which leads us to expect from any cause the same
events, which we have observed to result from similar causes. Where
the causes are entirely similar, the analogy is perfect, and the
inference, drawn from it, is regarded as certain and conclusive: nor
does any man ever entertain a doubt where he sees a piece of iron,
that it will have weight and cohesion of parts; as in all other
instances, which have ever fallen under his observation. But where the
objects have not so exact a similarity, the analogy is less perfect,
and the inference is less conclusive; though still it has some
force, in proportion to the degree of similarity and resemblance.
The anatomical observations, formed upon one animal, are, by this
species of reasoning, extended to all animals; and it is certain, that
when the circulation of the blood, for instance, is clearly proved
to have place in one creature, as a frog, or fish, it forms a strong
presumption, that the same principle has place in all. These
analogical observations may be carried farther, even to this
science, of which we are now treating; and any theory, by which we
explain the operations of the understanding, or the origin and
connexion of the passions in man, will acquire additional authority,
if we find, that the same theory is requisite to explain the same
phenomena in all other animals. We shall make trial of this, with
regard to the hypothesis, by which we have, in the foregoing
discourse, endeavoured to account for all experimental reasonings; and
it is hoped, that this new point of view will serve to confirm all our
former observations.

  83. First, It seems evident, that animals as well as men learn
many things from experience, and infer, that the same events will
always follow from the same causes. By this principle they become
acquainted with the more obvious properties of external objects, and
gradually, from their birth, treasure up a knowledge of the nature
of fire, water, earth, stones, heights, depths, &c., and of the
effects which result from their operation. The ignorance and
inexperience of the young are here plainly distinguishable from the
cunning and sagacity of the old, who have learned, by long
observation, to avoid what hurt them, and to pursue what gave ease
or pleasure. A horse, that has been accustomed to the field, becomes
acquainted with the proper height which he can leap, and will never
attempt what exceeds his force and ability. An old greyhound will
trust the more fatiguing part of the chace to the younger, and will
place himself so as to meet the hare in her doubles; nor are the
conjectures, which he forms on this occasion, founded in any thing but
his observation and experience.

  This is still more evident from the effects of discipline and
education on animals, who, by the proper application of rewards and
punishments, may be taught any course of action, and most contrary
to their natural instincts and propensities. Is it not experience
which renders a dog apprehensive of pain, when you menace him, or lift
up the whip to beat him? Is is not even experience, which makes him
answer to his name, and infer, from such an arbitrary sound, that
you mean him rather than any of his fellows, and intend to call him,
when you pronounce it in a certain manner, and with a certain tone and

  In all these cases, we may observe, that the animal infers some fact
beyond what immediately strikes his senses; and that this inference is
altogether founded on past experience, while the creature expects from
the present object the same consequences, which it has always found in
its observation to result from similar objects.

  84. Secondly, It is impossible, that this inference of the animal
can be founded on any process of argument or reasoning, by which he
concludes, that like events must follow like objects, and that the
course of nature will always be regular in its operations. For if
there be in reality any arguments of this nature, they surely lie
too abstruse for the observation of such imperfect understandings;
since it may well employ the utmost care and attention of a
philosophic genius to discover and observe them. Animals, therefore,
are not guided in these inferences by reasoning: Neither are children:
Neither are the generality of mankind, in their ordinary actions and
conclusions: Neither are philosophers themselves, who, in all the
active parts of life, are, in the main, the same with the vulgar,
and are governed by the same maxims. Nature must have provided some
other principle, of more ready, and more general use and
application; nor can an operation of such immense consequence in life,
as that of inferring effects from causes, be trusted to the
uncertain process of reasoning and argumentation. Were this doubtful
with regard to men, it seems to admit of no question with regard to
the brute creation; and the conclusion being once firmly established
in the one, we have a strong presumption, from all the rules of
analogy, that it ought to be universally admitted, without any
exception or reserve. It is custom alone, which engages animals,
from every object, that strikes their senses, to infer its usual
attendant, and carries their imagination, from the appearance of the
one, to conceive the other, in that particular manner, which we
denominate belief. No other explication can be given of this
operation, in all the higher, as well as lower classes of sensitive
beings, which fall under our notice and observation.*

  * Since all reasonings concerning facts or causes is derived
merely from custom, it may be asked how it happens, that men so much
surpass animals in reasoning, and one man so much surpasses another?
Has not the same custom the same influence on all?

  We shall here endeavour briefly to explain the great difference in
human understandings: After which the reason of the difference between
men and animals will easily be comprehended.

  1. When we have lived any time, and have been accustomed to the
uniformity of nature, we acquire a general habit, by which we always
transfer the known to the unknown, and conceive the latter to resemble
the former. By means of this general habitual principle, we regard
even one experiment as the foundation of reasoning, and expect a
similar event with some degree of certainty, where the experiment
has been made accurately, and free from all foreign circumstances.
It is therefore considered as a matter of great importance to
observe the consequences of things; and as one man may very much
surpass another in attention and memory and observation, this will
make a very great difference in their reasoning.

  2. Where there is a complication of causes to produce any effect,
one mind may be much larger than another, and better able to
comprehend the whole system of objects, and to infer justly their

  3. One man is able to carry on a chain of consequences to a
greater length than another.

  4. Few men can think long without running into a confusion of ideas,
and mistaking one for another; and there are various degrees of this

  5. The circumstance, on which the effect depends, is frequently
involved in other circumstances, which are foreign and extrinsic.
The separation of it often requires great attention, accuracy, and

  6. The forming of general maxims from particular observation is a
very nice operation; and nothing is more usual, from haste or a
narrowness of mind, which sees not on all sides, than to commit
mistakes in this particular.

  7. When we reason from analogies, the man, who has the greater
experience or the greater promptitude of suggesting analogies, will be
the better reasoner.

  8. Byasses from prejudice, education, passion, party, &c. hang
more upon one mind than another.

  9. After we have acquired a confidence in human testimony, books and
conversation enlarge much more the sphere of one man's experience
and thought than those of another.

  It would be easy to discover many other circumstances that make a
difference in the understandings of men.

  85. But though animals learn many parts of their knowledge from
observation, there are also many parts of it, which they derive from
the original hand of nature; which much exceed the share of capacity
they possess on ordinary occasions; and in which they improve,
little or nothing, by the longest practice and experience. These we
denominate Instincts, and are so apt to admire as something very
extraordinary, and inexplicable by all the disquisitions of human
understanding. But our wonder will, perhaps, cease or diminish, when
we consider, that the experimental reasoning itself, which we
possess in common with beasts, and on which the whole conduct of
life depends, is nothing but a species of instinct or mechanical
power, that acts in us unknown to ourselves; and in its chief
operations, is not directed by any such relations or comparisons of
ideas, as are the proper objects of our intellectual faculties. Though
the instinct be different, yet still it is an instinct, which
teaches a man to avoid the fire; as much as that, which teaches a
bird, with such exactness, the art of incubation, and the whole
economy and order of its nursery.

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