One view suggests that the motivation and purpose of the laws providing for the removal of Aboriginal children from their parents was child protection, with government policy makers and officials responding to an observed need to provide protection for neglected, abused or abandoned mixed-descent children An example of the abandonment of mixed race children in the 1920s is given in a report by Walter Baldwin Spencer that many mixed-descent children born during construction of The Ghan railway were abandoned at early ages with no one to provide for them. This incident and others spurred the need for state action to provide for and protect such children.
Other 19th- and early 20th-century contemporaneous documents indicate that the policy of removing Aboriginal children from their parents related to different beliefs: that given the catastrophic population decline of Aboriginal people after white contact that they would "die out", that the 'full-blood' tribal Aboriginal population would be unable to sustain itself, and was doomed to inevitable extinction. Ideas of eugenics and fears of miscegenation with a desire to maintain white racial purity were related to the ideology that mankind could be divided into a civilisational hierarchy. This supposed that the civilisation of northern Europeans was superior to that of Aborigines, based on comparative technological advancement. Some adherents to these beliefs considered any proliferation of mixed-descent children (labelled 'half-castes', 'crossbreeds', 'quadroons' and 'octoroons' ) to be a threat to the nature and stability of the prevailing civilisation, or to a perceived racial or civilisational "heritage". For example, in the 1930s, the Northern Territory Protector of Natives, Dr. Cecil Cook, perceived the continuing rise in numbers of "half-caste" children as a problem. His proposed solution was:
  • Generally by the fifth and invariably by the sixth generation, all native characteristics of the Australian Aborigine are eradicated. The problem of our half-castes will quickly be eliminated by the complete disappearance of the black race, and the swift submergence of their progeny in the white.
Similarly, the Chief Protector of Aborigines in Western Australia, AO Neville, wrote in an article for The West Australian in 1930:
  • Eliminate the full-blood and permit the white admixture to half-castes and eventually the race will become white.