the philosopher of biology michael ruse wrote that thompson "had little time for natural selection." instead, thompson emphasised "the formal aspects of organisms", trying to make a case for self-organization through normal physical and chemical processes. ruse notes that, following aristotle, thompson used as an example the morphology of jellyfish, which he explained entirely mechanically with the physics of a heavy liquid falling through a lighter liquid, avoiding natural selection as an explanation. ruse is not sure whether thompson believed he was actually breaking with "mechanism", in other words adopting a vitalist (ghost in the machine) view of the world. in ruse's opinion, thompson can be interpreted as arguing that "we can have completely mechanical explanations of the living world" – with the important proviso that thompson apparently felt there was no need for natural selection. ruse at once adds that "people like darwin and dawkins undoubtedly would disagree"; they would insist that