In Germany, Ernst Heinrich Haeckel devoted his life to defending Darwin’s theory of biological evolution. He was not reluctant to consider rigorously the philosophical ramifications and theological consequences of cosmic evolution in general and human evolution in particular. As a natural philosopher, he contributed to a sound scientific understanding of the nature of humankind and its proper place in the universe (despite the unavoidable limitations of his Victorian epoch).
In Haeckel’s major philosophical work, The Riddle of the Universe at the Close of the Nineteenth Century (1900), he presented a naturalist interpretation of evolution within a cosmic perspective. The dogmatic dualism of Kant and Spencer was rejected, showing Haeckel’s familiarity with the chemistry, biology, anthropology, psychology, and history of philosophy during his time. He was particularly influenced by Spinoza, Goethe, and Darwin. A major zoologist and evolutionist, he is primarily remembered for his early defense of Darwinism in Germany and for establishing his “biogenetic law.” Committed to the view that both science and speculation are necessary for a sound interpretation of the cosmos, he developed his own scientific cosmology. His monistic philosophy rejected the following three theistic dogmas: a personal God, the personal immortality of the human soul, and the freedom of the individual will. Also, he rejected the concept of empty space but supported strict determinism.
Haeckel’s philosophy of nature relied upon experience and inference (rational speculation), both sources of knowledge being held indispensable. It rejected anthropism, that is, that powerful and worldwide cluster of erroneous opinions that opposes the human organism to the rest of nature and represents it to be the preordained end of an organic creation, an entity essentially distinct from it, a godlike being. As a result, he rejected (a) the anthropocentric dogma, which maintains that humankind is the preordained center and aim of all terrestrial life (Haeckel advocated a cosmic perspective), (b) the anthropomorphic dogma, which maintains that God, the creator, sustainer, and ruler of the world, has human attributes and that the human being is therefore godlike instead of the other way around (Haeckel rejected all forms of theism but was sympathetic to scientific pantheism), and (c) the anthropolatric dogma, which maintains an ontological dualism and the personal immortality of the human soul (Haeckel’s own view was monistic and, as such, strictly naturalistic).
Briefly, the antropistic view of the world that sprang from these three dogmas is in irreconcilable opposition to Haeckel’s monistic system. Indeed, it is rejected by his new cosmological perspective. Likewise, he held that his evolutionary monism was capable of resolving the following problems: (a) the nature of matter and force, (b) the origin of motion, (c) the origin of life, (d) the order in nature, (e) the origin of simple sensation and consciousness, (f) rational thought and speech, and (g) freedom of will. Consequently, he maintained that the great law of substance remained the only simple, comprehensive, mysterious, and enigmatic riddle of the universe. He espoused the view that this law is the fundamental cosmic fact of reality establishing the eternal persistence of matter and force (this was the law that guided his monistic philosophy through the complexity of the universe to a solution of world problems).
What emerges as crucial in Haeckel’s philosophy is his severe criticism of the fallacy of anthropism with its anthropocentric, anthropomorphic, and anthropolatric dogmas. Clearly, he denied the basic assumptions of theism, for he held that his monistic, pantheistic, and evolutionary cosmology would eliminate these errors. In place of these dogmas, he advocated the law of substance, with its naturalist implications supported by scientific knowledge. Humankind is seen as a product of biological development, and all of its faculties are totally within nature. To Haeckel, there is no need for transcendental or supernatural assumptions (the independent existence of the external natural world prior to the emergence of humankind and the limited constituting ability of human consciousness are both accepted as basic facts of physical reality).
Haeckel found empirical support for his evolutionary perspective in paleontology, comparative embryology, comparative anatomy and physiology, and comparative psychology. Comparative morphology demonstrated that our species is a vertebrate, tetrapod, mammal, primate, and hominoid. There was even biological proof for the asserted close affinity of our species with the great apes. In all important respects, the symboling human animal presents all the anatomical marks of a great ape, with reason being the only aspect that essentially distinguishes it from all its lower or earlier evolutionary relatives.
Paleontology supported an evolutionary interpretation of the great chain of being, or scala naturae, previously acknowledged by the nonevolutionists. There is a hierarchy in nature represented by successive chronological developments, for example, protozoa, protista, metazoan, invertebrates, fish, amphibians, reptiles, birds, and mammals, as well as developments in plants and insects. As such, the paleontological record supported the evolutionary unity of nature and documented Haeckel’s monistic view.
Embryology or ontogeny demonstrates a common parentage of all organisms in general and of all primates in particular. Embryology implies that all existing primates share a common ancestry, our species and the great apes (orangutan, chimpanzee, and gorilla) being the latest products of primate evolution. Haeckel formulated his own biogenetic law to express the causative connection that exists between ontogeny and phylogeny: “Ontogenesis is a brief and rapid recapitulation of phylogenesis, determined by the physiological functions of heredity (generation) and adaptation (maintenance)….In man, as in all other organisms, the embryonic development is an epitome of the historical development of the species.” Haeckel’s biogenetic law of recapitulation was regrettably exploited by extreme cultural evolutionists and condescending racists at the expense of technologico-economically little developed and non-literate societies arbitrarily described as primitive and backward peoples. Later, this law was misinterpreted even more cynically by racist politicians in unethical ways of which Haeckel certainly would have disapproved.
Physiology and psychology demonstrated that the vital processes in our species are subject to the same physical and chemical laws as those of all other animals. Likewise, its mental faculties or psychic life (including its rational faculty) are said to differ from those of the nearest related animals only in degree and not in kind, that is, quantitatively but not qualitatively. The human mind or soul (consciousness) evolves during the ontological development of the human individual and is dependent upon the common structure and normal functioning of the psychic organ, the human brain. As a result of this naturalist interpretation of the development of mental activity, personality can lay no claim to immortality.
Haeckel acknowledged that reason does distinguish our species from the other animals, but reason is not a supernatural aspect of the human mind. He held that reason is an activity of the human mind that has evolved along with the evolution of the brain. To account for the evolutionary emergence of consciousness (and eventually the emergence of reason), Haeckel adopted a position of panpsychism. His position of panpsychism resulted from the investigation of comparative psychology. However, a distinction should be made between a moderate and an extreme form of panpsychism. A moderate form of panpsychism merely maintains that all living objects manifest an aspect (and therefore a degree) of psychic development or sensitivity (this is Haeckel’s own position). However, an extreme form of panpsychism advocates that ultimately everything in reality is psychic in nature, and therefore an ontological monism grounded in mind is necessary. A naturalist may support an ontological monism grounded in naturalism, for the degrees of sensitivity manifested by biological organisms depend upon the development of the central nervous system and brain. As a result, one may speak of the naturalistic emergence of psychic activity. By maintaining that the human mind differs from the psychic activity of lower animals merely in degree, rather than in kind, Haeckel’s view agreed with those of Huxley and Darwin. His position does not imply anthropocentrism, a doctrine that he rejected. He merely acknowledged that in the long series of biological organisms that have evolved, our species is the most complex, and that degrees of sensitivity in the function of mental activity are directly related to the degrees of complexity in the structure of the central nervous system and brain. Therefore, since its central nervous system and brain are the most complex in the animal kingdom, it is not surprising that the human animal should manifest the highest degree of consciousness. In fact, our species is capable of self-consciousness primarily because of its superior central nervous system and brain and their role in sociocultural interaction.
Haeckel accepted Huxley’s pithecometra thesis, that is, that the differences between our species and the great apes are not so great as those between the apes and the lower monkeys. Denying the different proofs that have been given for the immortality of the human soul (i.e., theological, cosmological, onto-logical, teleological, moral, and ethnological), he thought that there are sound scientific arguments to support this denial (i.e., physiological, historical, experimental, pathological, ontological, and phylogenetic arguments grounded in empirical evidence).
While acknowledging the incompleteness of the fossil record in rock strata, Haeckel maintained that, in the course of human evolution, an ape-man without speech, or the “missing link” (Pithecanthropus alalus), had once existed between the prehistoric apes and the present human animal. Unlike Darwin, who correctly held that Africa was the birthplace of our species, Haeckel taught that Asia was the cradle of hominid evolution. In fact, he even hypothesized that an Asian landmass, which he referred to as Lemuria (now vanished), had been the geographical location where our species had its origin from a hominoid ancestor. Haeckel’s own lectures on the evolution of our species were very popular. His hypothesis that the missing link would be found in Asia even inspired Eugene Dubois to travel to Java, where he subsequently discovered the fossil hominid Pithecanthropus erectus (1890-1892). Haeckel’s hypothesis had actually led to a major scientific discovery in emerging physical anthropology.
Haeckel’s monism rested upon the law of substance, which in turn rested upon two great cosmic theorems: (1) the conservation of matter (Lavoisier’s chemical law of the persistence or indestructibility of matter presented in 1789) and (2) the conservation of energy (Mayer’s and Helmholtz’s physical law of the persistence of force presented in 1842). On the basis of all of this, Haeckel concluded that the sum total of force or energy in the universe remains constant, no matter what changes take place around us. Energy is eternal and infinite, like the matter on which it is inseparably dependent. The two cosmic laws are fundamentally one, their unity being expressed in the formula of the law of the persistence of matter and force. Haeckel referred to this fundamental cosmic law as the supreme law of substance (axiom of constancy of the universe). The law supported universal causality and cosmic unity. Haeckel’s monistic ontology has benefited in the wake of Einstein’s theory of relativity. The demonstrated interchangeability of matter and energy scientifically justifies a naturalist monism, for matter and energy are merely two manifestations of the one ontological stuff of this universe.
There are six essential characteristics of Haeckel’s view of the cosmos: (1) the universe is infinite in space, (2) the universe is eternal in time, (3) the universe is a perpetuum mobile (movement is an innate property of substance), (4) there is no internal purpose whatever in the universe), (5) there is an eternal repetition in infinite time of the periodic metamorphosis of the cosmos, and (6) the idea of God is identical with that of nature or substance. Haeckel’s scientific and pantheistic interpretation of reality is reminiscent of the positions held by Bruno, Spinoza, Goethe, Humboldt, and Einstein.
Haeckel argued that evolution and theism are irreconcilable. The evolutionary perspective led to the paradoxical conception of God as a “gaseous vertebrate” or gaseous being (by the expression “gaseous vertebrate,” Haeckel is referring to the invisible and personal aspects of the traditional Christian conception of God). He concluded that monistic pantheism is necessarily the world-system of the modern scientist and that the modern thinker who has science and art needs neither a special church nor a narrowly enclosed portion of space.
Haeckel thought it very probable that unicellular evolution had taken place on planets elsewhere in this universe and that higher plants and animals have evolved on these planets; very questionable that these higher plants and animals are identical in development to those on earth; wholly uncertain whether there are vertebrates, mammals, and humans on other planets; much more probable that there are different plants and animals elsewhere, and perhaps higher beings transcending the intelligence of earthy human beings. He was also confident that future progress in astronomy, geology, physics, chemistry, biology, and anthropology would bear out his positions.
Haeckel’s cosmological and evolutionary perspective is expressed in the following fundamental theorems:
(a) the universe is eternal and infinite,
(b) its substance, with its two attributes (matter and energy), fills infinite space and is in eternal motion,
(c) this motion runs on through infinite time as an unbroken development, with a periodic change from life to death (from evolution to devolution), (d) the innumerable bodies that are scattered about the space-filling ether all obey the same law of substance (while the rotating masses slowly move toward their destruction and dissolution in one part of space, others are springing into new life and development in other quarters of the universe), (e) our sun is one of these countless perishable bodies, and our earth is one of the countless transitory planets that encircle them, (f) our earth had gone through a long process of cooling before water, in liquid form (the first condition for organic life), could settle on it, (g) the ensuing biogenetic process, the slow development and transformation of countless organic forms, must have taken millions of years, (h) among the different kinds of animals that arose in the later stages of the bio-genetic process on earth, the vertebrates have far outstripped all other competitors in the evolutionary process, (i) the most important branch of the vertebrates, the mammals, were developed later (during the Triassic period) from the lower reptilian, (j) the most perfect and most highly developed branch of the class mammalian is the order of primates, which first put in an appearance (by development from the lowest prochoriata) at the beginning of the Tertiary period, (k) the youngest and most perfect twig of the branch of primates is our species, which sprang from a series of humanlike apes toward the end of the Tertiary period, and (l) consequently, the so-called history of the world (i.e., the brief period of a few thousand years that measures the duration of civilization) is an evanescently short episode in the long course of organic evolution, just as this episode, in turn, is merely a small portion of the history of our planetary system.
As our earth is a mere speck in the infinite universe, so humankind is but a tiny grain of protoplasm in the perishable framework of organic nature. Haeckel proposed that it is very probable that on many planets of other solar systems, plants and animals have evolved similar to those on earth, perhaps even higher plants, animals, and vertebratelike beings with intelligence that may even far transcend our own species on earth. As such, he had envisioned the new science of exobiology with its logical consequence for exoevolution.
In Monism as Connecting Religion and Science (1892), Haeckel’s science-oriented evolutionary philosophy had rejected outright homotheism (theoan-thropomorphism), that is, attributing human shape, flesh, and blood to the gods. He held that the Christian concept of a personal God is totally erroneous in light of scientific evidence and the evolutionary perspective. Unlike Darwin, Spencer, and Huxley, Haeckel was not reticent in expounding the naturalist and atheist implications of the theory of evolution as he understood them. His philosophy of humankind was grounded in the special sciences informed by critical reason. He held that the evolution of our species could be sufficiently accounted for by the sciences, that is, there is no need to distort or ignore established natural facts by dogmatically holding to unverifiable philosophical assumptions for the sake of retaining a theological orientation. He was bold enough to clearly point out that there are no longer any legitimate reasons for believing in a supernatural origin and spiritual essence of humankind. Hence, for Haeckel, there is no need to construct elaborate philosophical systems in an attempt to reconcile the special sciences with theistic theology. Theology is simply being replaced by ethically inspired and morally responsible scientific understanding and philosophical appreciation. His strong reaction to the dogmatism of the churches was reinforced by their refusal to acknowledge the implications of a naturalist interpretation of biological evolution. Few natural philosophers have been so honest and persistent in their quest for truth as Ernst Haeckel, who, even when considered solely within the limits of his time, remains a major scientific figure of undeniable historic significance.
Haeckel’s Last Words on Evolution: A Popular Retrospect and Summary (1905) restated his philosophical position for the last time. The work contains three essays given at the last public delivery by the great man who was rightfully referred to as the “Darwin of Germany.” He continued to maintain the thesis that naturalism, or evolutionary monism, and supernaturalism are diametrically and irreconcilably opposed. He wrote that the papacy is anything but a divine institution (describing it as “the greatest swindle the world has ever submitted to”). In his essay “Charles Darwin as an Anthropologist” (1909), Haeckel acknowledged his indebtedness to the great genius for the fact of organic evolution and its mechanism of natural selection, which support a monistic view of the origin and nature of humankind; but unfortunately, Haeckel resisted the new theories of mutation and the gene.
In his last book, Eternity (1916), Haeckel once again maintained the cosmic unity of matter and energy within the endless “becoming and passing away” of things in this universe, as well as the role of chance throughout organic evolution. Of course, his respect for the special sciences, especially biology and anthropology, had not diminished. And he continued to stress the critical need for keeping church and state separated in the quest for truth.
Haeckel’s works consistently discarded vitalism, teleology, positivism, agnosticism, and mysticism. They defended mechanism, hylozoism, a moderate form of panpyschism, pantheism, monism (matter-energy or matter-force), and the use of reason. Within his evolutionary framework, he never veered from his basic assumptions, that is, that naturalist or anti-spiritualist monism supports an eternal, infinite, self-sufficient, indestructible, uncreated, and endlessly evolving universe. Today, the empirical evidence to support the doctrine of evolution is sufficient to convince any open-minded scientist, philosopher, or even an enlightened theologian. In its general implications, Haeckel’s Weltanschauung (worldview) remains untarnished after more than a century of continued scientific advancement. The fact that his millions of years have become billions of years is a correction resulting in a greater perspective that he would have happily embraced. It may be charged that Haeckel neglected to establish a rigorous epistemology, avoided mental analysis, underestimated the influence of social evolution (he could have added a supplementary set of cultural theorems, including a less ambiguous and more elaborate ethical stand), and even deified the universe. He was primarily a zoologist, and a great one, who, like Giordano Bruno and other pantheists, did not experience a need for a special divinity apart from and beyond that of the evolving cosmos itself.
Haeckel’s views were the source of considerable controversy in biology, philosophy, and religion. He distinguished himself in zoology, making contributions to embryology and taxonomy. Unfortunately, he advocated a limited form of spontaneous generation to account for the origin of the simplest protoplasmic substance from inorganic carbonates. Nevertheless, he was convinced of the essential unity of the inorganic and organic worlds. In fact, he upheld the essential unity of the entire universe. His doctrine of substance (ontological monism) maintained that the ultimate nature of the stuff of the universe is unknown, but it rejected traditional dualism as well as atomistic materialism and idealistic monism. Yet, Haeckel’s scientific writings advocated naturalism and rejected supernaturalism. His evolutionary monism was grounded in the law of the conservation of matter and energy.
Haeckel advocated the reconciliation of science (empiricism) and philosophy (rationalism), but rejected religious faith as a substitute for critical inquiry. He held that introspection must be supplemented with experimental psychology and physiology. Clearly, for him, consciousness itself is a natural phenomenon and the product of biological evolution. Haeckel’s pantheism advocates monism, a “natural equality” of egoism and altruism, the improvement of education and the human condition through more science, and is grounded in naturalism, humanism, and the evolutionary viewpoint within a cosmic perspective. With only a few but important modifications, this philosophical worldview remains in step with modern thought.
Ernst Haeckel died in Jena on August 9, 1919. He had spent an incredibly successful life as a professor and author, who belonged to over 90 learned societies and received many honors for his scientific research. An unabashed atheist, Haeckel had been courageous enough to take seriously the far-reaching consequences of evolution, while many of his contemporaries remained either indifferent or silent to the growing empirical evidence in the special sciences, from geopaleontology to comparative morphology, that documented the fact of evolution. Indeed, it is a fitting tribute to this daring evolutionary naturalist, with a cosmic perspective, that his book The Riddle of the Universe (1900) remains an important popular work of lasting intellectual value.
- DeGrood, D. H. (1965). Haeckel’s theory of the unity of nature. Boston: Christopher.
- Haeckel, E. (1878). Freedom in science and teaching. London: C. Kegan Paul.
- Haeckel, E. (1892). Monism as connecting religion and science: The confession of faith of a man of science.
- London: Adam & Charles Black. Haeckel, E. (1904). The wonders of life: A popular study of biological philosophy.New York: Harper & Brothers.
- Haeckel, E. (1905). Last words on evolution. New York: Peter Eckler.
- Haeckel, E. (1905). The riddle of the universe (1900). New York: Harper & Brothers.