In the ‘Dialogues on Natural Religion’, David Hume put forward various objections to the Argument from Design which is a central pillar of natural theology, including William Paley’s version of it. This note briefly explains the three most significant objections David Hume presented to the argument from Design.
Hume’s objections to the argument from design centre firstly on the nature of the analogy that is being used in that argument, secondly on the claim that the argument is a posteriori argument, and thirdly on the claim that believing in a creator and designer God is the best explanation of what we observe in the universe.
He starts by claiming that the analogy which Cleanthes provided is weak. By providing a comparison between deductive argument and inductive argument, Hume coins an example of an analogy that from the blood circulation in fish and frog the blood circulation in humans, other animals, or the circulation of the sap in vegetables can be inferred; while the blood circulation in, for say, Titius and Maevius can be inferred by knowing the blood circulation in humans. He argues that the resemblance of the universe to any other creatures is a matter of doubt, and affirming such a resemblance is based on guess and presumptions.
Then he tackles the strength of a posteriori argument. He asserted that a posteriori argument is based on observation and experience, and we based on the similarity between effects verify similarity causes, and from the similarity of causes affirm similarity in effects. However, unless the causes or effects, either way, are entirely similar, the inference cannot be perfect, certain, and necessary. He adds that any change in specifications and criterion of what we try to use their analogy will weaken the strength of inference. He also inserts that we cannot transfer a conclusion from parts of a whole to the whole, and operations of some parts cannot be generalised to the origin of the source of those parts. Likewise, arguing based on analogy as a posteriori argument cannot necessarily and perfectly prove the existence of an intelligent designer, here God.
Furthermore, he claims that arrangements and orders by themselves do not imply and show a design. Even matter can be the source of observable adjustment, independent of any other external sources. He expresses that it is possible that many objects and elements make arrangements based on some “internal” cause. So it is not necessary to have an external cause or designer to be able to justify the observable arrangement in the universe, however, as far as we can observe and experience.