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Mr. Challeron
3738 N. Clifton Avenue
Chicago, ILL 60613

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Dear Mr. Challeron:

	I'm sorry I don't have time to examine your letter with the
care that would be required to be very helpful to you.  Two remarks,
however.

	1. The interviewer didn't send me a copy of the {\it Chicago
Tribune} article, and I don't remember using the phrase ``still undefined
kind of computer'', so I don't know how it was used in the article.
In general, I regard AI problems as programming problems rather
than as hardware problems.

	2. The problem of an automatic chauffeur is harder than your
letter indicates.  The ultimate goal in this matter is a program that
could be used by someone who couldn't drive, e.g. a child, very
old person or blind person.  However, even something that would
permit a qualified driver to take his eyes off the road for a
prolonged period on a present day freeway is quite difficult because
of rare events.  The probability of a crash has to be less than
$10↑{-9}$ per hour in order to be as good as good human driving.
Therefore, the automatic drive must distinguish among shadows, paper
bags, animals, people, and hard objects like tires on the road as
well as recognizing erratic driving by other cars.  Each of these
is rare but frequent enough so that it can't be ignored.  It must
not take violent action to avoid running over a paper bag or shadow,
but must do so to avoid a child.

	Incidentally, I haven't actively worked in the field of
automatic driving and am presently not active in robotics at all.

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Sincerely,       

John McCarthy    
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JMC/ra 
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