A strictly Darwinian process of evolution is insufficient to account for a universal principle such as the pursuit of happiness. Admittedly, natural selection as an unguided (“blind”) and purposeless process may explain why human beings seek to survive, but it fails to explain why we seek to thrive. Human flourishing seems superfluous to the individuals who are chosen to pass on useful adaptations via chance mutations to their progeny. Put differently, assuming biological evolution is true, “survival of the fittest”—as the main mechanism of natural selection—only tells us why some individuals are “fit” for survival, not why all those individuals who survive engage in “quality of life.” It makes more sense to attribute the principle of human happiness—quality of life—to intelligent design. That is, since the Creator of the universe designed mankind for happiness by creating us in his own image, we naturally desire to prosper.
The existence of God, as a necessary condition of the possibility of happiness or summum bonum (“the highest good”), has already been argued by Christian philosophers, such as Immanuel Kant. Read Immanuel Kant, Critique of Practical Reason, trans. Thomas Kingsmill Abbott (Mineola, NY: Dover Publications, 2004), 132-141.