The World as Will and Representation (original German title, Die Welt als Wille und Vorstellung; sometimes translated as The World as Will and Idea) is the central work of Arthur Schopenhauer and one of the most important philosophical works of the 19th century.

This work begins with a statement that it assumes its reader's prior knowledge of Kant's philosophy as a prerequisite; Schopenhauer was the only major philosopher to maintain the transcendental idealism of Kant. The book's appendix provides a critique of the Kantian philosophy, which rejects most of Kantian ethics and significant parts of his epistemology and aesthetics.

For Schopenhauer, Kant had ignored inner experience, as intuited through the will, which was the most important form of experience. Schopenhauer's metaphysics go beyond the limits that Kant had set, but do not go so far as the rationalist system-builders that preceded Kant. Other important differences are Schopenhauer's rejection of eleven of Kant's twelve categories, arguing that only causality was important. Matter and causality were both seen as a union of time and space and thus being equal to each other. Bryan Magee rather sensationally called this a prototype for the theory of relativity.

The first volume was published in 1819 and the second volume in 1844. The first volume consisted of four books - covering his epistemology, ontology, aesthetics and ethics, in order. Schopenhauer's critique of language influenced Wittgenstein; he said that words were inaccurate substitutes for perception. He also criticised the scientific method as inappropriate for dealing with the questions of the nature of existence. In its place, he celebrated feeling and inner-experience. Aesthetics were praised as an expression of these feeling, which could never be achieved by dry argument or science. Music was given a special place and was seen as a copy of the will, whilst all other arts were seen as methods of giving knowledge the upper-hand over willing, that it is otherwise always denied.

Schopenhauer's notion of the will comes from the Kantian things-in-itself – which was supposed to be objects outside of time and space, which could never be experienced or described. Schopenhauer pointed out that anything outside of time and space could not be differentiated, so the thing-in-itself must be one and we must all be part of it. Our inner-experience must be a manifestation of the noumena realm and the will is the inner kernal of every being. All knowledge gained of objects is seen as self-referential, as we recognise the same will in other things as is inside us. Book Two sees electricity and gravity described as fundamental forces of the will. Knowledge is something that was invented to serve the will and is present in both animals and humans. It is subordinate to the demands of the will for all animals and most men, but knowledge can dominate in aesthetic contemplation or in philosophy.

The ethics of Schopenhauer may appear, at first, to be similar to the irrational sentimentalism of Hume, as he defines morality as identical to compassion and denies any link between reason and morality. However, he is much more metaphysical than Hume and he sees compassion as the bridge to eventual denial of the will. The will conflicts with itself through the egoism that every human and animal is endowed with. Compassion arises from a transcendence of this egoism (or: a penetration of the isolation of an "illusory" perception of individuality to participate in the suffering of another) and can serve as a clue to the possibility of going beyond desire and the will. Great art, including music and visual arts, is claimed to provide another experience of the suspension of the will, akin to pity/compassion, but only fractionally related to the "breaking" of the will through Asceticism. Schopenhauer categorically denies the existence of the "freedom of the will" in the conventional sense, and only adumbrates how the will can be "released" or negated, but is not subject to change, and serves as the root of the chain of causal determinism. His praise for asceticism led him to praise Buddhism and Vedanta Hinduism, as well as some monastic sects of Catholicism. He expressed contempt for Protestantism, Judaism and Islam, which he saw as optimistic, devoid of metaphysics and cruel to animals.

The book makes constant references to suicide in its examples – somewhat unnecessarily, at times. This was seen as an unacceptable way of escaping from the horrors of life, as the will still lives on afterwards and has not denied itself, as occurs in asceticism. Suicide is seen as a deed of the will, as it takes place to avoid physical pain – unlike asceticism. It was denied that suicide was immoral, however, as it was commonly thought to be, at the time.

The second volume consisted of several essays expanding topics covered in the first. Most important are his reflections on death and his theory on sexuality, which saw it as a manifestation of the whole will making sure that it will live on and depriving humans of their reason and sanity in their longing for their loved ones. Whilst this has been much improved on since, his honesty on the subject is unusual for the time and the central role of sexuality in human life is now widely accepted. Less successful is his theory of genetics: he argued that humans inherit their will, and thus their character, from their fathers, but their intellect from their mothers and he provides examples from biographies of great figures to illustrate this theory; unfortunately for Schopenhauer, there has been no evidence in the science of genetics to back up his claims. Many feel put off Schopenhauer for his attacks on contemporary philosophers such as Fichte, Schelling and Hegel, in this second volume.

Influence

The value of this work is much disputed. Some rank Schopenhauer as one of the most original and inspiring of all philosophers, whilst others see him as inconsistent and too pessimistic. Whilst his name is not well-known outside Germany, he has had a huge impact on psychoanalysis and the works of Freud; some researchers have even questioned whether Freud was telling the truth when he said that he had not read Schopenhauer until his old age. The notion of the subconscious is present in Schopenhauer's will and his theory of madness was consistent with this. Also, his theory on masochism is still now widely proposed by doctors. Nietzsche, Popper and Tolstoy were all strongly influenced by his work.

He was the first philosopher to be explicitly atheist (Hume only ever confessed to being agnostic). He even believed in the theory of evolution, before Darwin began to publish his work. His interest in Eastern philosophy brought new ideas to the West. His respect for the rights of animals – including a vehement opposition to vivisection - has led many modern animal rights activists to look up to him.

Criticism

• Kant saw inner-sense as subject to time. Schopenhauer was thus violating Kant's laws when he said that the thing-in-itself could be known through inner-experience.

• His notion that we can know things about the will but never actually directly know the will is very clumsy and vague.

• The concepts of time and space in the work have since been supplanted by physical knowledge of spacetime.

• The will is seen as blind and chaotic, yet it manifests itself in teleological nature, in the phenomenal realm. To explain this, he employs Plato's Ideas as an intermediary, yet does not explain whether they are part of the will or the representation. He later says that art involves the study of the Platonic Idea, yet this would be hard to apply to paintings of obscure objects.

• His view on suicide is widely ridiculed. It seems to have been taken from Buddhist teachings on the subject, yet Schopenhauer did not believe in thorough-going reincarnation. It seems to be of little importance to the man that has committed suicide and left the horrors of the world behind that the will lives on afterwards.

• He contradicts himself over asceticism. At times, he says that it involves the most terrible pain, yet he also says that it leads to a cheefulness that contrasts with the restless suffering of those that still will. Also, he mentions accounts of ascetics feeding themselves to crocodiles and being buried alive as examples of the denial of the will, but then says that the only form of suicide that involves a denial of the will comes from starvation.

• Perhaps, the biggest criticism for most people is that Schopenhauer preached asceticism as the answer to the problems of the world, yet made no attempt to practise what he preached. He conserved his money strigently, ate at fancy restaurants and had more than one affair. However, some accounts of his life, in philosophy dictionaries, tend to pay a little too much attention to his private life and exaggerate parts. Bertrand Russell produced a very derogatory article on Schopenhauer, in this tone. The infamous story of him throwing a woman down a stairs is often told without mentioning the provocation he received beforehand, and there is evidence that he was a very polite and courteous man in his dealings with others at his favourite restaurant.