Re: Lisp history: IF, etc.

On 4/15/2024 6:31 PM, Lawrence D'Oliveiro wrote:

On Mon, 15 Apr 2024 18:01:46 -0600, Jeff Barnett wrote:

I also remember McCarthy in the late 1960s being obsessed with logic and
philosophy and randomly spouting off discussions such as how processing
of
     Sir Walter Raleigh was the author of "The Lie"
     Did the Queen know that Raleigh wrote "The Lie"?

might produce

     Did the Queen know TRUE?

The word “know” has its own connotations which might be confusing things,
though. What if it were

     Did the Queen believe that Raleigh wrote "The Lie"?

might produce

     Did the Queen believe TRUE?

If you think that’s a meaningless statement, then how about

     An ounce of prevention is worth a pound of cure
     Do anti-vaxxers believe that an ounce of prevention is worth a pound
         of cure?

and you realize that, trying to substitute “conspiracy theorists” for X
in

     Do X believe TRUE?

is a process fraught with pitfalls. ;)

The above was one of McCarthy's examples to show that blind application
of "logic techniques", e.g., substitution or unification, to other
representations, e.g., natural language was fraught with perils. In the
example, SWR = TL equiv TRUE and so TRUE was substituted. Most know
better today but at the time, a lot of smart people had too simplified,
i.e., ridiculous idea of how we could just slip formal logic in and
solve all of our AI problems without some vary necessary updates to
"formal logic" particularly preconditions of application rules.
--
Jeff Barnett