This paper argues from extensive research findings
in design psychology and industrial design processes, as
well as our own observations, that interactive generative
systems can be powerful tools for human designers. Moreover,
interactive generative systems can fit naturally into human
design thinking and industrial design practice. This discussion
is focused on aesthetic design fields like knitwear and
graphic design, but is largely applicable to major branches
of engineering. Human designers and generative systems
have complementary abilities. Humans are extremely good
at perceptual evaluation of designs, according to criteria
that are extremely hard to program. As a result, they can
provide fitness evaluations for evolutionary generative
systems. They can also tailor the biases that generation
systems use to reach useful solutions quickly. We discuss
an application of these approaches: Kelly's evolutionary
systems for color scheme design. Automatic design systems
can work interactively with human designers by generating
complete designs from partial specifications, that can
then be used as starting points for designing by modification.
We discuss an application of this approach: Eckert's
garment shape design system.