People often say "even if Hitler didn't exist, another angry leader would have probably risen to power and the Holocaust would have still happened". How virulent was antisemitism in Western Europe before Hitler came to power? Were ideas like racial cleansing and industrial genocide being discussed?

In short:

Racial cleansing, yes to some extent

Industrial genocide, no to some extent

In (more) detail:

Antisemitism was broadly quite common in central Europe during the early-mid twentieth century, however this was an issue which varied by region. The Nazi's ideology of race was one which developed entirely within the context of European thought and tradition, and interns of its Jew-hatred, did not add any new substantive features in character, but simply brought pre-existing ones to an unprecedentedly radical scale.

National Socialist ideology viewed the world through the lens of ethno-linguistic nationalism. Within this framework race became a central pillar of Nazi ideology. The regime propagated Völkischthought, which constructed a perception of the nation as being a living organism composed of the Volk, which distinguished what was German, by what was not, groups which were then collectively identified as ‘racial aliens’.

Influenced by scientific racism, racial mysticism, and social-Darwinism, the Nazis sought to bring about the creation of the ideal national community. This future was to be created by, and for the Volk, excluding, and at the detriment, of outside groups. A key consideration of ideology was the strengthening of the Aryan race. While the life of the Volkwas considered sacred, the sanctity of all other life was dismissed.

Thus National Socialist ideology embraced race as the founding principle of morality, forgoing all existing political, religious and social principles. In the name of strengthening and protecting the race, the concept of euthanasia was strongly supported, and the eradication of other races for the betterment of the Volkembraced as a moral racial action. This principle informed and guided the all-encompassing Nazi programme of discrimination and persecution which reached through religious, racial, legal, political, and economic spheres.

Scientific Racism and Racial Hygiene

The development of Nazi ideology happened within a framework established by popular ideas of race propagated by scientific and academic figures, including anthropologists and social scientists. Within a wider context of European modern history, colonialism was justified upon the belief of a racial hierarchy between superior and inferior racial groups. This helped to justify the demonization of the Jews.

Concurrently, there was also a line of thought amongst some social scientists, such as Cesare Lombroso, the founder of criminal anthropology, which alleged that criminality could be diagnosed based upon physical characteristics. This theory, while rejected by a number of scientists, legitimised state intervention and pre-emptive action against individuals which posed a ‘threat’ to society. Likewise, in a similar vein, Alfred Ploetz, founder of the German Society for Racial Hygiene, used social-Darwinism to promote the concept of racial hygiene. Ploetz would advocate using euthanasia to promote racial hygiene as a tool for removing ‘unproductive/unworthy’ individuals from the population. These ideas would be highly influential to the Nazis.

Artur de Gobineau, a French aristocrat, furthered the concept of scientific racism by claiming that culture was the product of race, and that some races were superior than others because they held more “cultural capital”. De Gobineau feared that intermixing of different races would lead to the decline of the Aryan race, to which he suggested eugenics as a solution. These ideas of racial hygiene and decline would prove influential to the Nazis, and helped lead to the spread of an idea that presented progress as the result of racial purity achieved by restricting non-productive social and racial groups. Similarly Ernst Haeckel, a German student of Charles Darwin, promoted a scientific racism based upon a evolutionary racial hierarchy and argued for maintaining the racial purity of the Aryan race by killing those whose survival was ‘unsuitable’ or ‘unproductive’ to the race.

(cont...)