The more efficient computers become at inducing new knowledge,

The more efficient computers become at inducing new
knowledge, the more widely that knowledge will be applied,
even in matters of life and death. It is essential that such
knowledge be open to inspection. This means that designers of
learning systems have a public duty to use comprehensible
description languages-- even if that means sacrificing
performance. Otherwise we run the risk of generating truly
"unknowable knowledge."
-- Richard Forsyth
-- Machine Learning for Expert Systems