"Biogeneettisen peruslain teoreettinen perusta oli Haeckelin dogmaattinen ja kaiken epäilyksen ulkopuolella oleva vakaumus polveutumisopin pätevyydestä. 'Polveutumisoppi... ei tarvitse... mitään muita todistuskappaleita'".Ernst Haeckel, Generellen Morphologie der Organismen.2. nide s. 299 f. Scherer S & Junker R, Evoluutio - Kriittinen analyysi s. 180. Datakirjat 2000. Ontologinen naturalismi on puhdas usko siihen, että luonnonlait, aine ja sattuma ovat kaikki, mitä on olemassa. Tästä seuraa seuraa alttius kehäpäättelylle alkuperäkysymyksissä. Tämä on kuitenkin historia-tiedettä, ei puhdasta luonnontiedettä - ja sille pitää olla näiltä osin eri metodit. Evoluutioteoriaa pidetään helposti tieteellisenä jo sen vuoksi, että muita naturalistisia mahdollisuuksia ei oikeastaan ole näköpiirissä. Jacques Monod'n laajalevikkisen kirjan otsikko on oireellinen: Sattuma ja välttämättömyys.

"The result became known as Haeckel's 'Biogenetic Law': Ontogeny recapitulates phylogeny. That famous phrase, memorized by generations of uncomprehending schoolchildren, means that the fetal development of an individual (ontogeny) is a speeded-up replay of millions of years of species evolution (phylogeny). In other words, a human embryo passes through various stages during its nine months in the womb: invertebrate; fish; amphibian; reptile; mammal; primate; ape; man. A fascinating concept, but the 'law' is unture and was rejected by biologists around 1900. Nevertheless, it has become embedded in many school courses and textbooks and continues to be taught." Richard Milner Encyclopedia of evolution  (1990) s. 44.

"The present generation cannot imagine the role he played in his time, far beyond his actual scientific performance… Haeckel's easy hand at drawing made him improve on nature and put more into the illustrations than he saw… one had the impression that he first made a sketch from nature and then drew an ideal picture s he saw it in his mind." Goldschmidt RB (1956) The golden age of zoology; portraits from memory. University of Washington Press, Seattle London  (pp. 31-3.)

 “There are not many personalities who have so powerfully influenced the development of human culture and that, too, in many different spheres  as Haeckel.” Erik Nordenskiold, History of Biology, pp. 505-506 in Daniel Gasman, The Scientific Origins of National Socialism: Social Darwinism in Ernst Haeckel and the German Monist League (New York, American Elsevier, 1971), p. xxx.

 �?from a scientific point of view it must be regarded as utterly valueless. Its biological section is a rehash of the History of Creation, Anthropogeny, and the monograph on the plastitude, as little attention as possible being paid to the immense progress made by scientific research since then. As a matter of fact, biology takes up only one quarter of the volume; the rest is devoted to psychology, cosmology, and theology. The cosmological section gives evidence of the author's hopelessly confused ideas on the simplest facts of physics and chemistry.� Nordenskiold, History of Biology, p. 524: (kommentti Maailmanarvoituksista) in Gasman p. 29.