Schumacher himself considered A Guide for the Perplexed to be his most important achievement, although he was better known for his 1973 environmental economics bestseller Small Is Beautiful, which made him a leading figure within the ecology movement.
His daughter wrote that her father handed her the book on his deathbed, five days before he died and he told her "this is what my life has been leading to".
[1] As the Chicago Tribune wrote, "A Guide for the Perplexed is really a statement of the philosophical underpinnings that inform Small Is Beautiful".
Schumacher argues that the current philosophical "maps" that dominate western thought and science are both overly narrow and based on some false premises.
Schumacher put forward what he considers to be the four great truths of philosophy: Schumacher was very much in favor of the scientific spirit, but felt that the dominant methodology within science, which he called materialistic scientism, was flawed and stood in the way of achieving knowledge in any other arena than inanimate nature.
Schumacher believed that this flaw originated in the writings of Descartes and Francis Bacon, when modern science was first established.
By contrast, Schumacher argues that the descriptive sciences are interested in the truth in the wider sense of the word.
Such an approach, Schumacher argues, provides a grey, limited, utilitarian worldview without room for vitally important phenomena like beauty and meaning.
Schumacher believes in contrast to materialistic science that what is in doubt should be shown prominently, not hidden away or ignored.
Materialistic scientism rejects the idea of levels of being, but for Schumacher this leads to a one-sided view of nature.
Schumacher accepts that evolution as a generalization within the descriptive science of biological change has been established beyond any doubt whatsoever.
The evolutionist doctrine purports to prove and explain biological change in the same manner as the proof and explanation offered by the instructional sciences.
Schumacher quotes the 1975 Encyclopædia Britannica as an example of this view: "Darwin did two things: he showed that evolution was in fact contradicting scriptural legends of creation and that its cause, natural selection, was automatic leaving no room for divine guidance or design.
For Schumacher one of science's major mistakes has been rejecting the traditional philosophical and religious view that the universe is a hierarchy of being.
For Schumacher, a similar jump in level of being takes place between plant and animal, which is differentiated by the phenomenon of consciousness.
Schumacher uses this perspective to contrast with the materialistic scientism view, which argues that what is true is inanimate matter, denying the realness of life, consciousness and self-consciousness, despite the fact each individual can verify those phenomena from their own experience.
Schumacher goes on to say that nothing is "more conducive to the brutalisation of the modern world" than calling humans the "naked ape".
[2] Schumacher argues that what defines humanity are our greatest achievements, not the common run of the mill things.
He argues that human beings are open-ended because of self-awareness, which as distinct from life and consciousness has nothing mechanical or automatic about it.
"[2] Schumacher argues that by removing the vertical dimension from the universe and the qualitative distinctions of "higher" and "lower" qualities which go with it, materialistic scientism can in the societal sphere only lead to moral relativism and utilitarianism.
Schumacher does not claim there is any scientific evidence for a level of being above self-consciousness, contenting himself with the observation that this has been the universal conviction of all major religions.
He quotes R. L. Gregory in Eye and Brain, "Perception is not determined simply by the stimulus pattern, rather it is a dynamic searching for the best interpretation of data.
"[5] He points out that materialistic science is principally based on the sense of sight and looks only at the external manifestation of things.
Descartes promised humanity would become "masters and possessors of nature", a point of view first popularised by Francis Bacon.
Lacking a sense of higher values Western societies are left with pluralism, moral relativism and utilitarianism, and for Schumacher the inevitable result is chaos.
Schumacher suggests that the most fruitful advice in this field can be gained by studying the Fourth Way concept of "external considering".
Early attempts at developing human-powered vehicles included three- and four-wheelers and involved wheels of different sizes.
Great art is a multi-faceted phenomenon, which is not content to be merely propaganda or entertainment; but by appealing to people's higher intellectual and emotional faculties, it is designed to communicate truth.
When entertainment and propaganda are transcended by, and subordinated to, the communication of truth, art helps develop our higher faculties and that makes it "great".
He argues that this is because most ethical debate sidesteps any "prior clarification of the purpose of human life on the earth.