The question of Tahiti population at contact was first addressed by assessing the reliability of early and later estimates, and then by a retrodiction based on the first reliable censuses and data on trends. Cook’s famous estimate of 204,000 Tahitians, affected by a wrong number of districts, has been reworked based on his own and the Forsters’ observations, using coast length and the age and sex structure of Tahiti population at contact in relation to infanticide, resulting in a range of 156,000-188,000 persons in 1774, before Boenechea’s flu in 1772 and the 1774 flu epidemics. The discrepancies between Wilson’s 16,050 and other missionaries’ estimate of 50,000 as of 1797 are puzzling, but the 1829-1830 missionary estimates were strongly affected by Tahitians’ resistance to Christianization. The twentieth century estimates are affected by a political context related to colonization - decolonisation, leading to the fact that researchers favour low estimates. McArthur uses missionary data, assuming that baptisms are births, although before the conversion was completed, baptisms included adults and children of all ages. She bases her estimate of 30,000 Tahitians at contact in 1767 on Wilson’s number of 16,050, who applied the size of nuclear households, 6 persons, to clans. Oliver followed her, however not excluding numbers twice as high or more. Our retrodiction on the 1848 and 1881 censuses, based on qualitative missionary reports on sanitary situation and data of Rarotonga that experienced similar events as Tahiti, yield, with conservative assumptions, 180,000 persons at contact, showing consistent results with early navigators’ estimates. My own PhD experience in the late 1980s shows that scholars’ re-estimates were constrained, directly or indirectly, by political considerations related to the guilt syndrome and colonialist ideology. This appears in the frequent contradictions found in their works to support low estimates in order to reduce the decline, despite evidence of dramatic epidemics and a steady decline extending almost throughout the 19 th century. The same attitude of denial is found in some missionary, administrative and medical reports, particularly on the Marquesas in the late 19 th century. Colonisation was associated with various ideologies, related to anthropology’s early attempts based on theories of evolutionism, functionalism and structuralism, occasionally resulting in fictions such as “primitive thinking”, “ahistorical societies” and “collective unconscious”, that were part of the justification of colonisation and its mistakes.