One of the key differences between LISP-like languages and other languages is that in LISPs, code and data are the same thing. This makes it possible to do things such as have a program modify some of it's algorithms during runtime as it "learns" new things, as a native part of the language.
Another aspect that goes into this, though not as much, is LISP's ability to easily add new language semantics through macros. This makes it possible to actually go in and define a DSL that your AI works with and can evolve in, with the potential for that language to grow, self-correct, and evolve while the AI is running.
Agreeing with Quadrescence, LISPs history of use goes a long way towards LISPs image that it's good for AI. Why is LISP used for AIWhy is LISP used for AI covers the history in much more detail.
