Carl Sagan on The Kalam cosmological argument
Sagan challenged the assumptions behind first-cause arguments, asking what caused God and noting that science, not theology, addresses origins.
Sagan addressed first-cause arguments directly in Cosmos (1980) and in his public lectures. His response was characteristically elegant: if we say that God created the universe, we must then ask what created God. If God can exist without a cause, so can the universe. The first-cause argument does not solve the problem of origins — it merely postpones it by one step.
He was also sceptical of the second premise — that the universe began to exist. Sagan noted that the Big Bang describes the beginning of the current expansion of the universe, not necessarily the absolute beginning of all physical reality. Oscillating universe models, quantum gravity scenarios, and other cosmological hypotheses allow for a universe without a first moment. The question is open, and premature certainty is unwarranted.
Sagan's deeper objection was methodological. Cosmological arguments attempt to answer empirical questions — what caused the universe? — with a priori reasoning. But questions about the origin and structure of the cosmos are scientific questions, best addressed by observation, experiment, and mathematical modelling. Philosophy can clarify the concepts, but it cannot substitute for data.
“If we wish courageously to pursue the question, we must, of course, ask next where God comes from. And if we decide this to be unanswerable, why not save a step and decide that the origin of the universe is an unanswerable question?”