Descartes’ Rules
for the Direction of the Mind (see my blog dated June 22, 2015) gives not
only the basic rules for a methodic approach of scientific problems. It
contains also a number of statements that have a wider meaning; statements that
have sense in the daily contact of men with each other. Some seem obvious. Nevertheless
we often forget to apply them. For example, in Rule IX Descartes tells us that
people are often more impressed by difficult high-flown far-fetched reasonings
that they don’t completely understand than by simple transparent arguments. Knowledge,
so Descartes, must not be deduced from what looks important and obscure but
from what is easy and common. Isn’t it so that – my instance – a politician
that uses bombastic language without content and not founded on the facts tends
to have more followers than one who says the truth in a clear way?
Descartes’ words made me think of what is called
Occam’s razor. Occam (or Ockham) himself didn’t use the word “razor” for his
principle and he formulated it also in different words than we do today. He was
a Franciscan friar who lived from about 1287-1347. The maxim that made him
famous was in his words “It is vain to do with more what can be done with
fewer”. Today this is read as “Entities are not to be multiplied without
necessity”. For example, take the reasoning (1) “All men are mortal”- (2) “Philosophers
are men” - (3) “Socrates is a philosopher” - (4) “So Socrates is mortal”. This
reasoning contains the entity “philosopher”, which is superfluous here, for if
we would define “philosopher”, we would get something like “a man who studies
fundamental problems”. Fill in the definition in our syllogism and you’ll see
that the entity “philosopher” is superfluous in this explanation why Socrates
is mortal.
Sometimes Occam’s razor is considered meaning “Say it
as simple as possible”. This interpretation is not correct, for arguing from several
entities can be more brain breaking than a single statement with one or two
entities that comprises a lot. Aristotle thought that bodies like stones fall
on the ground because it’s there that their “natural place” is. However,
reality appeared to be more complex and now we use complicated Newtonian
suppositions and formulas for explaning gravity or, even better, Einstein’s
theory of general relativity, even though Aristotle’s view was simpler.
Occam’s razor has a long history. Actually Occam was
not the first one who formulated the principle. Once clearly formulated by him it
had a big influence. Many scientists applied it and many philosophers referred
to it. Wittgenstein, one of my favourite philosophers, said it this way: “If a
sign is not necessary then it is meaningless” (Tractatus logico-philosophicus: 3.328). Or later “Occam’s Razor ...
says that unnecessary elements in a symbolism mean nothing.” (5.47321).
Things that we first thought to be simple can be quite
complicated but Occam’s razor helps us avoid unnecessary complications. It’s
not completely harmless, as we have seen, and take care of the pitfall of
oversimplification of Occam’s razor, but nevertheless as a rule of thumb you
can start with the idea to keep it as simple as you can and then look what it
brings. It helps prevent that you’ll be deceived by people who want to impress
with an air of erudition and scholarship. For as Descartes warned us in Rule XII:
Learned people are often so ingenious that they find a way to be blind even in
matters that are clear as such and that every simple mind understands.