The aim ... is to provide a clear and rigorous basis for determining when a causal ordering can be said to hold between two variables or groups of variables in a model . . . . The concepts refer to a model-a system of equations-and not to the 'real' world the model purports to describe.

Engineering, medicine, business, architecture and painting are concerned not with the necessary but with the contingent - not with how things are but with how they might be - in short, with design.

All correct reasoning is a grand system of tautologies, but only God can make direct use of that fact

The aim ... is to provide a clear and rigorous basis for determining when a causal ordering can be said to hold between two variables or groups of variables in a model . . . . The concepts refer to a model-a system of equations-and not to the 'real' world the model purports to describe.

Human beings, viewed as behaving systems, are quite simple. The apparent complexity of our behavior over time is largely a reflection of the complexity of the environment in which we find ourselves.

By 1985, machines will be capable of doing any work Man can do.

The simplest scheme of evolution is one that depends on two processes; a generator and a test. The task of the generator is to produce variety, new forms that have not existed previously, whereas the task of the test is to cull out the newly generated forms so that only those that are well fitted to the environment will survive.