International Balzan Foundation Luigi Luca Cavalli

Are there Limits to Knowledge?
by Luigi Luca Cavalli-Sforza
ForMem RS, Geneticist, Stanford University
Balzan Symposium 2002
MEETING THE CHALLENGES OF THE FUTURE
A Discussion between “The Two Cultures”
Royal Society, London; 13 May 2002
Luigi Luca Cavalli-Sforza
On one hand, I resent even this question being asked. It looks like an attempt at
trying to limit my freedom of inquiry. It reminds me of the Great Inquisition, the
condemnation of Galileo. Is someone trying to decide what I am allowed to
learn and what I should not even try to learn? In a totally different perspective,
it reminds me of the irrepressible impression of ignorance which every honest
scientist feels when comparing the extent of what we know and what we don’t
know in our own field of knowledge. On a less emotional footing, there is, of
course, Heisenberg’s principle of indetermination. But all the innumerable attempts
at applying it out of context are probably unacceptable. Nevertheless,
we might wonder how many other comparable principles exist in other fields,
ones that we have violated out of ignorance. I find it more interesting, however,
to take a wholly pragmatic approach, and ask: what are the practical limits to
knowledge? Here I find many real limitations.
I find at least three important limits to knowledge. The first and most serious
one is the ambiguity of language. Almost every word has, in most languages, an
enormous variety of meanings. English probably has the greatest number of
words of all languages. This would seem to guarantee that it is closer to an ideal
situation, that there is only one meaning for each word, but the opposite is true.
I know of no statistics, but I suspect that English also has the greatest number
of meanings for each word. We think we are clear when we explain things, and
that we understand what other people tell us. The expectation is usually correct
in most real instances, but I suspect that it loses meaning when we approach
philosophy, where the use of words of a high degree of abstraction is common
and probably increasing. Examples are the verbs ’to be’, ’to exist’, ’to cause’,
and substantives derived from them. It may be because of personal limitations
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