Pluralism contends, says American Heritage Dictionary, "that no single explanatory system or view of reality can account for all the phenomena of life.”

Rationalism maintains "that reason is the prime source of knowledge and of spiritual truth.”

Existentialism “regards human existence as unexplainable...”  Søren Kierkegaard, an existential icon, said, “Where am I?  What is this thing called the world? Who has lured me into the thing and now leaves me here? How did I come into the world?”

Left to just reason and experience, life is an unsolvable puzzle.