A Compact and Comprehensive Study of Existential Philosophy. Emerging in the 19th and 20th centuries, existentialism challenges the notion that life comes prepackaged with meaning. Thinkers like Søren Kierkegaard, Friedrich Nietzsche, Jean-Paul Sartre, and Albert Camus rejected the idea that human purpose is dictated by external forces-be they divine, societal, or philosophical. Instead, they argued that meaning must be forged through personal choice, responsibility, and authenticity.