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sdi.3[e85,jmc]		Statement on SDI for RISKS
SDI

	Some remarks of mine about SDI on Stanford BBOARD have been
referred to.  For the benefit of non-readers of that BBOARD, they
mainly concerned whether I, like Chris Stuart, should use the IJCAI
platform to say something about it.  I said nothing in my lecture,
but in my press conference, added to my remarks on AI, the remark
that there was no principle of computer science that says that
programs of any particular task cannot be written and debugged.
Not much interest was shown by the assembled press; there was
exactly one question on that point.

	At the suggestion of Robert Jastrow, who is one of the main
scientific defenders of SDI, I made the same point in letters to
three Congressmen, said to be influential in the matter of SDI
appropriations.

	Now I shall say my opinion about SDI.

	1. If it can be done, it should.  If it affords complete
protect, that's great, and if it affords partial protection, that's
good.  The balance of terror is a bad thing.  Here are answers to
some counter arguments to its desirability.  (a) Joe Weizenbaum
says that it attempts a technological solution to a problem that
should be solved morally.  Alas, moral progress has been so slow
that almost the only moral problems to be even partially solved
are those that can at least partially been turned into technological
problems.  For example, the technology of contraception has greatly
reduced human unhappiness.  (b) It is argued that the Soviets would
have to attack at the first sign of deployment.  Every past imminent
advance by either side has in principle given the other side some
temptation to strike before it can be deployed.  So far as we know,
neither side has even come close to giving in to such temptation.
One reason is that the effect of any advance is always subject to
a probabilistic estimate, so temporizing has always looked better
than attacking.  Even if SDI works very well, it may be that no-one
will be able to be sure that it is that good.

	However, most likely the main reason has been is
that neither side ascribes the very worst intentions to the other
with certainty.  Each side has always said, "Perhaps they don't
actually mean to attack us.  Why have a nuclear war for sure instead
of only a certain probability?"  Anyway the Soviets have experienced
a period in which we had complete nuclear superiority and didn't
attack them.

2. My opinion is that if the physics of the problem permits a
good anti-missile defense the programs can be written and verified.
However, it will be quite difficult and will require dedicated work.
It won't be done by people who are against the whole project.
Computer checked proofs of program correctness will probably play
some role.  So will anticipating what kind of bugs would be most
serious and putting the biggest effort into avoiding them.  Having
many people go over and discuss all the critical parts of the
program will also be important.