Examining arguments from design › Natural religion and reasoning from experience

Natural religion here concerns what reason and observation can establish about the divine without an appeal to a particular revelation. The project therefore needs publicly examinable grounds for its inferences. Merely citing a religious teaching would change the kind of argument being made.

An argument from design begins with features of the world that appear ordered or purposive and proposes intelligence as their explanation. Cleanthes's version relies on an analogy with human productions. An analogy is a comparison through which known features of one case support an inference about another. Similarity supplies a reason only insofar as it bears on the feature being inferred.

Consider two unfamiliar instruments that resemble one another. Knowing how the first was made might provide a reason to investigate whether the second has a similar history. But the strength of that reason depends on the relevant resemblance and the surrounding evidence. Similar color would be weaker evidence of common construction than the same distinctive mechanism. This is a hypothetical illustration of the question Philo asks about the world and an artifact.

Cleanthes's appeal is therefore more specific than the claim that complexity exists. The relevant feature is the adjustment of means to ends: parts seem suited to accomplishing something together. Philo's challenge is whether this feature licenses the proposed inference when we move from familiar human productions to the universe itself.