Can you argue for God without quoting anything?

Not argue from scripture, or tradition, or authority, or experience that only believers have — but from premises available to anyone: that a world exists, that things change, that the physical constants sit where they do, that people have moral convictions they did not choose.

Natural theology is the discipline that says yes and then tries. It is the oldest continuous research program in Western philosophy, and its most interesting arguments are the ones its own practitioners have with each other.

What hangs on the answer

If theistic claims can be argued for on public premises, then religion is metaphysics — answerable to evidence and inference in the way that claims about causation or modality are, arguable with anyone, and wrong in the ordinary way if it is wrong.

If they cannot, something else has to be said. That belief rests on faith rather than argument, or that religious language is not in the business of stating facts at all, or that the whole question is malformed.

Almost nobody in the tradition thinks reason gets you everything. The standard scholastic position, set out by Aquinas, is a division of labor: reason can reach God's existence, unity and eternity; revelation is required for the Trinity, the Incarnation, the resurrection. Reason establishes the foundation, revelation supplies what could not have been guessed.

The arguments, in brief

Each of these has its own long history, and its own page.

From the existence of the world. Contingent things do not explain themselves; the explanation terminates in something that does not need one. The cosmological argument.

From the concept of God alone. No observation required: unpack what a maximally great being is and existence is alleged to fall out. The ontological argument.

From apparent design. Paley's watch found on a heath, and the inference to a watchmaker. Darwin is generally taken to have finished the biological version; the fine-tuning of physical constants is where the argument lives now.

From morality. Objective obligations look like the kind of thing that needs a ground. Kant made God a postulate of practical reason rather than a conclusion of theoretical reason — a distinction his successors often lost.

From religious experience. Millions report encounter with the divine. William Alston's Perceiving God argues this has the same epistemic structure as sense perception, and should be treated with the same default credence.

The dispute that actually matters

Here is the question that divides the field: what the arguments are for.

They are demonstrations. The scholastic and rationalist position. A successful argument yields a certain conclusion from premises reason compels. This is the register the Five Ways are written in, and it sets a bar almost nothing clears.

They raise probabilities. Richard Swinburne's program: no single argument is decisive, but each makes theism somewhat more likely, and the cumulative weight can carry it past even odds. This is a large concession and a shrewd one — it gives up certainty to gain arguments that survive objection, since an argument only has to add weight rather than settle the matter.

They confirm something that was already rational. Plantinga's reformed epistemology, and the most radical of the three. Belief in God may be properly basic — rationally held without being inferred from anything, in the way that your belief in other minds or in your own memory is. You did not argue your way to those and you are not irrational for holding them.

If that is right, the entire project is optional. Natural theology stops being the foundation of religious belief and becomes its defense: useful against objections, unnecessary for the belief itself.

Notice these three are three different accounts of what would even count as success, which is why the discipline's disputes so often run past each other.

The two great critiques

Hume, in the Dialogues, attacked on three fronts. The order in the world admits of natural explanation and sits alongside a great deal of disorder. Causal reasoning is learned inside the universe and may not extend to the universe. And the world is not enough like an artifact for the analogy to carry weight — it resembles a vegetable as much as a watch.

Kant went further and argued the whole theoretical enterprise is impossible. His claim is structural: the cosmological and design arguments smuggle in the ontological argument at the last step, and the ontological argument fails because existence is not a real predicate. The design argument, even granted, gets you an architect who shaped pre-existing matter — not a creator. God survives in Kant only as a postulate of practical reason, which is a different kind of thing entirely.

The objection from inside

The most interesting attack is not from atheists.

Karl Barth's Nein! in 1934, written against a fellow theologian, argues that natural theology is theologically illegitimate. If human reason can climb to God unaided, grace becomes a supplement rather than the condition of knowing God at all. Barth rejects the analogy of being that the whole project depends on. Knowledge of God is God's act, not our achievement, and a discipline premised otherwise has misunderstood its subject before it starts.

This is worth sitting with. A significant Christian tradition holds that arguing for God on neutral premises is not merely difficult but a category error about what God is — and the argument is theological rather than skeptical.

One distinction to keep

Natural theology is not natural religion.

Natural religion is a position: the deists' minimal theism, a God available to reason with no revelation required. Natural theology is a discipline that asks whether such conclusions are warranted.

You can do the discipline rigorously and reject the position — Aquinas did. You can hold the position with no rigor at all, which is roughly what the popular deists did.

Why it is worth your time

Natural theology is the longest-running test case for a question that is not about religion: what happens when you try to settle a dispute by argument alone, with a subject where the stakes are maximal and the evidence is contested by everyone.

Two thousand years in, the state of play is that the arguments are better than their critics usually allow and weaker than their defenders need. Which is where most genuinely hard questions end up, and the discipline is unusually honest about having arrived there.

Further reading