Philosophy of mind
Dualism is a set of views about the relationship between mind and matter (or body). It begins with the claim that mental phenomena are, in some respects, non-physical. One of the earliest known formulations of mind–body dualism was expressed in the eastern Sankhya and Yoga schools of Hindu philosophy (c. 650 BCE), which divided the world into purusha (mind/spirit) and prakriti (material substance). Specifically, the Yoga Sutra of Patanjali presents an analytical approach to the nature of the mind.
Dual economy
Dual economies are common in less developed countries, where one sector is geared to local needs and another to the global export market. Dual economies may exist within the same sector, for example a modern plantation or other commercial agricultural entity operating in the midst of traditional cropping systems. Sir Arthur Lewis used the concept of a dualistic economy as the basis of his labour supply theory of rural-urban migration. Lewis distinguished between a rural low-income subsistence sector with surplus population, and an expanding urban capitalist sector (see Dual-sector model). The urban economy absorbed labour from rural areas (holding down urban wages) until the rural surplus was exhausted.