On p. 13 Weikart writes:
Whatever Haeckel, Büchner, Carneri, and other leading Darwinists might have disagreed on, they agreed that natural processes could account for all aspects of human society and behavior, including ethics. They denied any possibility of divine intervention, heaped scorn on mind-body dualism, and rejected free will in favor of complete determinism. For them every feature of the cosmos - including the human mind, society, and morality - could be explained by natural cause and effect. Everything was thus subject to the ineluctable laws of nature. As a corollary to this, science became the arbiter of all truth. Not even ethics or morality could escape the judgments and pronouncements of science.
However, let's have a few peeks in Haeckel's Monism as Connecting Religion and Science. Haeckel writes:
Among the triumphs of the human mind the modern doctrine of evolution takes a foremost place. Guessed at by Goethe a hundred years ago, but not expressed in definite form until formulated by Lamarck in the beginning of the present century, it was at last, thirty years ago, decisively established by Charles Darwin, his theory of selection filling up the gap which Lamarck in his doctrine of the reciprocal influence of heredity and adaptation had left open. We now definitely know that the organic world on our earth has been as continuously developed, "in accordance with eternal iron laws," as Lyell had in 1830 shown to be the case for the inorganic frame of the earth itself; we know that the innumerable varieties of animals and plants which during the course of millions of years have peopled our planet are all simply branches of one single genealogical tree; we know that the human race itself forms only one of the newest, highest, and most perfect offshoots from the race of the Vertebrates.
So, yes, Haeckel acknowledges "eternal iron laws" of nature. However, what is worth noticing here is that Haeckel certainly doesn't devalue humans as he considers them to be "one of the newest, highest, and most perfect offshoots from the race of the Vertebrates", although this phrasing ("one of ...") certainly challenges the unique place of humans in nature.
As for the mind-body dualism, Haeckel writes:
The first task of a truly scientific psychology will therefore be, not, as hitherto, idle speculation about an independent immaterial soul-existence and its puzzling temporary connection with the animal body, but rather the comparative investigation of the organs of the soul and the experimental examination of their psychical functions. For scientific psychology is a part of physiology, the doctrine of the functions and the life-activities of organisms. The psychology and psychiatry of the future, like the physiology and pathology of to-day, must take the form of a cellular study, and in the first instance investigate the soul-functions of the cells.
Yes, for Haeckel psychology was a part of physiology, the study of soul-functions of organs. The approach is bottom-up, starting with soul-functions of cells; that is, physiology is further reduced to chemistry, which Haeckel in turn reduces to physics. This is all true; yet Haeckel didn't deny the importance of ethics.
Weikart discusses pp. 13-16 the relationship between Darwinism and naturalism without reaching any clear conclusion, although he claims that there is a positive correlation between being a Darwinist and being a naturalist. In the last paragraph on p. 16, Weikart writes:
What was it about Darwinian theory that produced a change in thinking about the value of human life? First, Darwinism implied that humans arose from animals, and many interpreted this to mean that humans did not have the special position accorded them in Judeo-Christian thought. Instead of being made in the image of God and falling from a pristine state of perfection, humans ascended from some kind of simian. In explaining the evolution of human mental and moral traits from animals, Darwin and most Darwinists denied the existence of an immaterial and immortal soul, a central tenet of the Judeo-Christian worldview that undergirded the sanctity of human life.
What Weikart might not know is that Biblical Hebrew does not make a distinction between body and soul; that distinction only appears in translations. But let's leave that as it is and instead again have a peek in Haeckel's Monism:
In all these dualistic and pluralistic systems the fundamental idea is that of anthropomorphism, or the humanising of God; man himself, as godlike (or directly descended from God), occupies a special position in the world, and is separated by a great gulf from the rest of nature. Conjoined with this, for the most part, is the anthropocentric idea, the conviction that man is the central point of the universe, the last and highest final cause of creation, and that the rest of nature was created merely for the purpose of serving man. In the Middle Ages there was associated at the same time with this last conception the geocentric idea, according to which the earth as the abode of man was taken for the fixed middle point of the universe, round which sun, moon, and stars revolve. As Copernicus (1543) gave the death-blow to the geocentric dogma, so did Darwin (1859) to the anthropocentric one closely associated with it.
So Weikart is right, indeed Haeckel considered Darwin to have given the death-blow to anthropocentrism just as Copernicus did to geocentrism.
In The Evolution of Man, chapter 30, "Results of Anthropogeny", Haeckel writes:
Just as most people much prefer to trace their family back to some degenerate baron or some famous prince rather than to an unknown peasant, so most men would rather have as parent of the race a sinful and fallen Adam than an advancing, and vigorous ape. It is a matter of taste, and to that extent we cannot quarrel over these genealogical tendencies. Personally, the notion of ascent is more congenial to me than that of descent. It seems to me a finer thing to be the advanced offspring of a simian ancestor, that has developed progressively from the lower mammals in the struggle for life, than the degenerate descendant of a god-like being, made from a clod, and fallen for his sins, and an Eve created from one of his ribs. Speaking of the rib, I may add to what I have said about the development of the skeleton, that the number of ribs is just the same in man and woman. In both of them the ribs are formed from the middle germinal layer, and are, from the phylogenetic point of view, lower or ventral vertebral arches.
Leaving the irony, if not sarcasm, aside, again Haeckel's point is clear, humans are offshoots of animals, but an advanced offshoot. Of course, this opens up for the idea that an even more advanced offshoot be possible; but that wasn't quite the Nazi idea.
Looking back at Weikart's sentence "[i]nstead of being made in the image of God and falling from a pristine state of perfection, humans ascended from some kind of simian", we may first note that nothing in Genesis indicates to us exactly what was meant by that "pristine state of perfection", and being created in that state didn't prevent Adam and Eve from going against the will of God, so what difference does it make?
In chapter 1, "The Origin of Ethics and the Rise of Moral Relativism", Weikart discusses primarily the etchics philosophy of German Darwinists with some flashbacks to Kant and Hume. While this discussion is in general quite fine, it has the drawback that Weikart consequently refers to the absolute Judeo-Christian ethics with its concept of free will, sanctity of human life and human rights. To my personal taste this is too much politico-religious preaching. What does free will mean? It means that you can be punished for your actions, because you could have acted differently, but chose not to do so. Free will does not mean more choices, when combined with an absolute ethics, since there is only one allowed choice. Human rights implies a limit to how badly you can be punished, and the same goes for the sanctity of human life. Components of a culture fit together and must be understood together.
As Weikart writes, Darwin and Haeckel were not against Christian ethics; they merely refounded it in biology as social instincts. But of course, once the moral wasn't absolute, it was relative and subject to change. This is all true; but things aren't quite as simple as that.
Society was changing; the landed nobility was loosing influence, and independent farmers were taking over country-side, while capitalists and workers were taking over the rapidly increasing cities. Had the clergy adapted to the changing environment? How could it have, if it didn't believe anything could change? Did the clergy have any message to searching souls that couldn't figure out their place in this society except a message about absolute morals and the free will to go to hell?
On pp. 32-33, Weikart after quoting Friedrich Jodl writes:
If morality is, as Jodl here alleges, nothing else than an adaptation to a changing environment, then morality has no fixed reference point. Moral laws or principles that are adaptive for one place and time are maladaptive in a different situation. Thus, moral principles are not fixed or objective, but constantly in evolutionary flux.
Again, the problem here really is that Weikart assumes there to be objective moral principles without giving any argumentation for that assumption. Could that be because his intended audience is fully convinced that such moral principles exist, and that they happen to coincide with their moral principles?
Continuing, Weikart writes p. 33:
Not only were moral principles changing, but moral beliefs in any given society "are always a step behind the times," claimed Jodl, since it takes time to adjust them to changing conditions. This means that the status quo cannot provide guidance about the validity or viability of any particular moral principles. Jodl thus provided Darwinian legitimation for attempts at moral and social reform. However, in an 1893 essay he specifically rejected the idea that humans have any inherent rights, so the social reform he advocated did not aim at bringing society into congruence with any universal principles.
Of course not; from where would Jodl have derived any universal principles?
Weikart spends the next pages demonstrating that Darwinists considered behavioral characteristics, e.g. criminality, to be inherited, and en route claiming that in the beginning of the 19th century the view was in general that social conditions caused such characteristics. Has Weikart forgotten that according to the Judeo-Christian worldview we have an inherited disposition to sin due to the fall of Adam and Eve? On page 37 Weikart writes:
One important theorist wedding Darwinian theory to psychiatry as the Italian psychiatrist Cesare Lombroso, whose influence extended throughout Europe. Heavily ingluenced by Darwin and Haeckel, Lombroso developed his theory of the "born criminal" in the 1870s. Lombroso believed that certain biological types are predisposed (or perhaps even constrained) by their heredity to commit crimes. Hoping to identify a link between physical and mental or moral characteristics, he studied the physical traits of known criminals, especially their cranial and facial characteristics.
Not to be too much of a spoil-sport, but I dare suppose that Weikart has heart about phrenology, the study of the correlation between cranial and facial characteristics and mental characteristics. This study was started by the Austrian physician F.J. Gall, who lived 1758 to 1828 and thus could hardly have been influenced by Charles Darwin.
On p. 38 Weikart mentions that Lombroso and others, including Darwin, considered the possibility of reversions to earlier stages of evolution, and that this was used as an explanation of "born criminals". Well, how much worse is this than the Judeo-Christian idea that parents begot handicapped children as a punishment for sin?
Another oddity is that you can only be a "born criminal" against a background with fixed criminal laws; that is, the notion of "born criminal" presupposes an objective moral. A morally deviant behavior can only be detected, if morally correct behavior is not questioned.
On p. 40, Weikart writes:
He [Eugen Bleuler] agreed with Lombroso that "moral idiots" and those having "moral insanity" are predisposed to criminality, and they are also usually antisocial and work-shy. While Bleuer [sic] and most German psychiatrists in the early twentieth century did not believe that specific moral commands are innate, they did believe that the aptitude to behave morally was an innate, biological trait. Those lacking a moral faculty are aberrant and a danger to society.
And in what way is this different from the Judeo-Christian belief that people can be possessed by Satan? Note the curse in Genesis 9 over Cana'an and his descendants for something Cana'ans father Ham had done. The Judeo-Christian conception of inheritance, while not biological in a modern sense, still implies that some people are morally bad, simply due to genealogy.
On p. 41, Weikart writes:
The idea that morality and immorality are primarily hereditary biological traits had tremendous implications for social policy, including education, justice, and penal reform, marriage reform, marriage policy, and the control of reproduction. Besides issues of marriage and sexual reform, to which we will retutn in later chapters, one of the crucial questions emerging from the rise of biological determinism concerned personal responsibility. How can society hold individuals responsible for their behavior - or at least predispositions toward that behavior - is programmed into their biological constitution? By rejecting human free will, many psychiatrists argued that responsibility as it had been traditionally conceived was misguided. However, they generally argued that society had a right to protect itself against morally "aberrant" individuals, so they were not necessarily advocating reduced penanlties for criminals.
And that witches were possessed by Satan didn't imply that they shouldn't be burned either. The Judeo-Christian burning of witches wasn't thought of as a punishment, but partly as protection of society against the influence of Satan and partly as cleansing the soul of the unfortunate witch of that influence.
In the next paragraph, Weikart writes:
Whether or not Darwinism actually implies materialism or determinism is a philosophical question beyond the scope of this work, but I have clearly demonstrated that historically many people thought it did. Evaluating Darwinism's contribution to the rise of moral relativism is even trickier.
This doesn't quite work. If morally aberrant behavior is detectable (except in a purely statistical sense), then there can be no moral relativism. Obviously you can only claim that something is wrong, if you believe that something is right. What Weikart doesn't quite catch here is that Darwinism only serves as a new explanation for something that earlier had been explained differently - the existence of moral absolutes is not changed.
On page 42, the last page of chapter 1, Weikart writes:
Historicism - the idea that everything is in flux and phenomena can only be understood as part of a historical process - was a feature common to most major systems of thought in nineteenth-century Europe, including Hegelianism and Marxism. ... [Weikart mentions non-Darwinist historicists] ... Darwinism was only one form of historicism among others, but it fostered moral relativism by providing scientific sanction for it. For some audiences this was more important than all the philosophizing Hegel or Dilthey could do.
It's an odd historian not to be an historicist. If Weikart isn't an historicist himself, why has he then written a book about (part of) the historical background for the holocaust?