Assumptions are not matters of fact but speculative constructs aimed at explaining phenomena that otherwise appear inexplicable. Examples in modern science are the concepts of gravity, inertia, chance events and photons (particles of light) formulated by Isaac Newton, Galileo Galilei, Charles Darwin and Albert Einstein, respectively. These assumptions replaced those of the Aristotelian science of medieval Europe. With changing circumstances existent assumptions may prove inadequate and even counterproductive. This was the reason for the scientific revolution of the 17th century, giving rise to modern science.
In the 20th century it became apparent to many scientists that the assumptions of that scientific revolution are no longer adequate, and are themselves in need of replacement. With hindsight, it is possible to see why this is so. The author demonstrates how these assumptions are illogical and are inconsistent with one another. These defects coupled with the need to understand the many newly observed phenomena that appeared in the 20th century, rendered modern science increasingly irrelevant.
He then goes on to critique in the same way the alternative assumptions suggested by 20th-century scientists. Many of these are also found wanting, but a few are more promising. He argues that using the latter it would be possible to construct in this century an alternative science that would enable us to deal effectively with the environmental, social and economic problems which are, in large measure, the results of the applications of modern science.