The teleological (design) argument

The design argument reasons from apparent order and purpose in the world to a designer.

• Aquinas' Fifth Way: things without intelligence (like natural bodies) act toward an end or goal. Something can only be directed to a goal by an intelligent being — as an arrow is directed by an archer. That being is God.
• William Paley (Natural Theology): if you found a watch on a heath, its intricate parts working toward a purpose would force you to conclude a watchmaker. Nature (the eye, the universe) shows the same contrivance, so it too has a designer.
• Paley argues from purpose (qua purpose) and from regularity (qua regularity), e.g. the orderly motion of the planets.

Paley watch

The cosmological argument

The cosmological argument reasons from the existence of the universe to a cause beyond it.

• Aquinas' first three Ways: from motion (change needs a first mover), from causation (a chain of causes needs a first cause), and from contingency (things that need not exist require a necessary being). An infinite regress, Aquinas argues, explains nothing — so there must be God.
• Leibniz: the Principle of Sufficient Reason — everything must have a reason. The whole contingent universe needs a sufficient reason for its existence, and that reason must be a necessary being outside it.

Watch the terms: contingent = might not have existed; necessary = cannot fail to exist. God is proposed as the necessary being.

Contingency

Which argument?

Tap a feature, then the argument it belongs to.

Hume challenges the arguments

In Dialogues Concerning Natural Religion, David Hume mounts several challenges:

• Weak analogy: the universe is not much like a machine or watch; it is more like a growing organism, so the analogy fails.
• Chance (the Epicurean hypothesis): given enough time, ordered arrangements could arise by chance, without design.
• Which designer? even if there is a designer, the argument cannot show it is one, perfect, infinite God — it might be many gods, an apprentice, or an imperfect maker.
• Causation: we never observe a universe being made, so we cannot reason confidently about its cause; and the fallacy of composition means what is true of parts need not be true of the whole.

Hume challenge

Kant challenges the arguments

Immanuel Kant argues these arguments overreach the limits of human reason:

• Against the cosmological argument: concepts like cause and necessity only apply within the world of possible experience. We cannot legitimately extend them beyond the universe to a first cause.
• Against the design argument: at best it could point to an architect who shaped pre-existing matter — not a creator God who made everything from nothing.

Response — Swinburne: Richard Swinburne argues that, taken together, design and order still make God the simplest and best explanation; the arguments raise the probability of God even if none is a proof.

Kant on the cosmological argument

Who argues what?

Tap a thinker, then their key move.

Aquinas Fifth Way

The big ideas to take into the exam

These a posteriori arguments contrast with the a priori ontological argument coming next. Press Finish for your score.