Holland's and Kauffman's work, together with Dawkins' simulations of evolution and Varela's models of autopoietic systems, provide essential inspiration for the new discipline of artificial life, This approach, initiated by Chris Langton (1989, 1992), tries to develop technological systems (computer programs and autonomous robots) that exhibit lifelike properties, such as reproduction, sexuality, swarming, and co-evolution.

Looking back to data, we can see if the consequences are plausible; looking forward to theory, we can see if general principles are suggested.

Model building is the art of selecting those aspects of a process that are relevant to the question being asked. As with any art, this selection is guided by taste, elegance, and metaphor; it is a matter of induction, rather than deduction. High science depends on this art.

This use of building blocks to generate internal models is a pervasive feature of complex adaptive systems.

When a new building block is discovered, the result is usually a range of innovations.

nonlinear interactions almost always make the behavior of the aggregate more complicated than would be predicted by summing or averaging.

Unwrapping occurs when the "solution" is explicitly built into the program from the start.