IPL-V Manual (1964) [pdf]
stacks.stanford.edu
stacks.stanford.edu
In the 1981 edition, that chapter has an outright section titled, in bold:
Symbol Manipulation is Needed to Make Computers Intelligent followed by a half dozen bulleted paragraphs why.
and then LISP is the Right Symbol-Manipulation Language to Learn.
People interested in AI would be exposed to texts like this and end up believing some of the stuff.