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On the
Importance of Experience
by Roger Bacon
There are two modes of acquiring knowledge,
namely, by reasoning and experience. Reasoning
draws a conclusion and makes us grant the
conclusion, but does not make the conclusion
certain, nor does it remove doubt so that the mind
may rest on the intuition of truth, unless the mind
discovers it by the path of experience; since many
have the arguments relating to what can be known,
but because they lack experience they neglect the
arguments, and neither avoid what is harmful nor
follow what is good. For if a man who has never
seen fire should prove by adequate reasoning that
fire burns and injures things and destroys them,
his mind would not be satisfied thereby, nor would
he avoid fire, until he placed his hand or some
combustible substance in the fire, so that he might
prove by experience that which reasoning taught.
But when he has had actual experience of combustion
his mind is made certain and rests in the full
light of truth. Therefore reasoning does not
suffice, but experience does.
This is also evident in mathematics, where proof
is most convincing. But the mind of one who has the
most convincing proof in regard to the equilateral
triangle will never cleave to the conclusion
without experience, nor will he heed it, but will
disregard it until experience is offered him by the
intersection of two circles, from either
intersection of which two lines may be drawn to the
extremities of the given line; but then the man
accepts the conclusion without any question.
Aristotle's statement, then, that proof is
reasoning that causes us to know is to be
understood with the proviso that the proof is
accompanied by its appropriate experience, and is
not to be understood of the bare proof. His
statement also in the first book of the
Metaphysics that those who understand the
reason and the cause are wiser than those who have
empiric knowledge of a fact, is spoken of such as
know only the bare truth without the cause. But I
am here speaking of the man who knows the reason
and the cause through experience. These men are
perfect in their wisdom, as Aristotle maintains in
the sixth book of the Ethics, whose simple
statements must be accepted as if they offered
proof, as he states in the same place.
He therefore who wishes to rejoice without doubt
in regard to the truths underlying phenomena must
know how to devote himself to experiment. For
authors write many statements, and people believe
them through reasoning which they formulate without
experience. Their reasoning is wholly false. For it
is generally believed that the diamond cannot be
broken except by goat's blood, and philosophers and
theologians misuse this idea. But fracture by means
of blood of this kind has never been verified,
although the effort has been made; and without that
blood it can be broken easily. For I have seen this
with my own eyes, and this is necessary, because
gems cannot be carved except by fragments of this
stone. Similarly it is generally believed that the
castors employed by physicians are the testicles of
the male animal. But this is not true, because the
beaver has these under its breast, and both the
male and female produce testicles of this kind.
Besides these castors the male beaver has its
testicles in their natural place; and therefore
what is subjoined is a dreadful lie, namely, that
when the hunters pursue the beaver, he himself
knowing what they are seeking cuts out with his
teeth these glands. Moreover, it is generally
believed that hot water freezes more quickly than
cold water in vessels, and the argument in support
of this is advanced that contrary is excited by
contrary, just like enemies meeting each other. But
it is certain that cold water freezes more quickly
for any one who makes the experiment. People
attribute this to Aristotle in the second book of
the Meteorologies; but he certainly does not
make this statement, but he does make one like it,
by which they have been deceived, namely, that if
cold water and hot water are poured on a cold
place, as upon ice, the hot water freezes more
quickly, and this is true. But if hot water and
cold are placed in two vessels, the cold will
freeze more quickly. Therefore all things must be
verified by experience.
But experience is of two kinds; one is gained
through our external senses, and in this way we
gain our experience of those things that are in the
heavens by instruments made for this purpose, and
of those things here below by means attested by our
vision. Things that do not belong in our part of
the world we know through other scientists who have
had experience of them. As, for example, Aristotle
on the authority of Alexander sent two thousand men
through different parts of the world to gain
experimental knowledge of all things that are on
the surface of the earth, as Pliny bears witness in
his Natural History. This experience is both
human and philosophical, as far as man can act in
accordance with the grace given him; but this
experience does not suffice him, because it does
not give full attestation in regard to things
corporeal owing to its difficulty, and does not
touch at all on things spiritual. It is necessary,
therefore, that the intellect of man should be
otherwise aided, and for this reason the holy
patriarchs and prophets, who first gave sciences to
the world, received illumination within and were
not dependent on sense alone. The same is true of
many believers since the time of Christ. For the
grace of faith illuminates greatly, as also do
divine inspirations, not only in things spiritual,
but in things corporeal and in the sciences of
philosophy; as Ptolemy states in the
Centilogium, namely, that there are two
roads by which we arrive at the knowledge of facts,
one through the experience of philosophy, the other
through divine inspiration, which is far the better
way, as he says.
Excerpted from Opus
Majus, by Roger Bacon
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Opus
Majus of Roger Bacon, Part 1
Opus
Majus of Roger Bacon, Part 2
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