Some years ago

I had a conversation

with a layman


flying saucers

—because I am scientific I know all about flying saucers!—

I said

I don't think there are flying saucers.

So my antagonist said

Is it impossible that there are flying saucers?

Can you prove that it's impossible?


I said,

I can't prove it's impossible.

It's just very unlikely.

At that he said

You are very unscientific.

If you can't prove it impossible

then how can you say that it's unlikely?

But that is the way that is scientific.

It is scientific only to say

what is more likely and what less likely,

and not to be proving all the time

the possible and


To define what I mean,

I might have said to him,


I mean that

from my knowledge of the world

that I see around me,

I think that it is

much more likely

that the reports of flying saucers

are the results of the

known irrational
characteristics of
terrestrial intelligence

than of the

unknown rational
efforts of
extra-terrestrial intelligence."

It is just more likely.

That is all.

Richard Feynman

published on Sep 21st 2011

The Character of Physical Law.

Cornell University Messenger Lectures (1964)

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