In a manner that shows concern only for oneself without regard for others' needs or feelings. Acting with personal interest as the primary motivation.
From 'selfish' (self + -ish) plus the adverbial suffix '-ly'. 'Selfish' appeared in English in the 1640s, coined during a period of growing individualism and Protestant emphasis on personal responsibility and salvation.
The concept of 'selfishness' as inherently negative is culturally constructed - many societies throughout history valued self-interest as natural and necessary for survival. The moral weight this word carries reflects Judeo-Christian and later Enlightenment values about social cooperation and individual duty to the community.
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