Final answer:
Edward Burnett Tylor theorized that religions evolve from simple to complex systems through stages from 'savagery' to 'barbarism' to 'civilization' in what is known as unilineal evolution. His definition of religion as 'the belief in supernatural beings' has been considered too restrictive to reflect the full variety of religious practices worldwide.
Step-by-step explanation:
British anthropologist Edward Burnett Tylor's view on the historical trajectory of religions is anchored in his broader theory of cultural evolution, which he outlines in his work 'Primitive Culture.' Acclaimed for his systematic approach to the study of religion, Tylor proposed that societies progress through a series of developmental stages from 'savagery' to 'barbarism' and eventually to 'civilization.' Within this framework, he considered religion to evolve through comparable stages, suggesting a unilineal evolution in which all cultures supposedly follow the same path toward an increasingly complex religious structure.
Tylor's definition of religion—"the belief in supernatural beings"—has been critiqued for being overly narrow, as it fails to encompass the entire spectrum of beliefs and religious practices across different cultures. His approach is reflective of nineteenth-century anthropology, which was characterized by ethnocentrism and a failure to recognize the uniqueness of each culture's historical trajectory. Unlike his contemporary Sir James Frazer, Tylor was less dismissive of unfamiliar belief systems, although he applied his own set of assumptions to his studies.