The argument from design stands as one of the most intuitively compelling arguments for the existence of a divine Creator. Yet, for many scientists and philosophers, Hume's critique and Darwin's theory of natural selection have definitely undermined the idea that we can draw any analogy from design in artifacts to design in nature. Here, we examine empirical studies from developmental and experimental psychology to investigate the cognitive basis of the design argument. From this it becomes clear that humans spontaneously discern (...) purpose in nature. When constructed theologically and philosophically correctly, the design argument is not presented as conclusive evidence for God's existence but rather as an abductive, probabilistic argument. We examine the cognitive basis of probabilistic judgments in relationship to natural theology. Placing emphasis on how people assess improbable events, we clarify the intuitive appeal of Paley's watch analogy. We conclude that the reason why some scientists find the design argument compelling and others do not lies not in any intrinsic differences in assessing design in nature but rather in the prior probability they place on complexity being produced by chance events or by a Creator. This difference provides atheists and theists with a rational basis for disagreement. (shrink)

Why do design arguments—particularly those emphasizing machine metaphors such as “Organisms and/or their parts are machines”—continue to be so convincing to so many people after they have been repeatedly refuted? In this essay I review various interpretations and refutations of design arguments and make a distinction between rationally refuting such arguments (RefutingR) and rendering them psychologically unconvincing (RefutingP). Expanding on this distinction, I provide support from recent work on the cognitive power of metaphors and developmental psychological work indicating a basic (...) human propensity toward attributing agency to natural events, to show that design arguments “make sense”unless one is cued to look more closely. As with visual illusions, such as the Müller-Lyer arrow illusion, there is nothing wrong with a believer's cognitive apparatus any more than with their visual apparatus when they judge the lines in the illusion to be of unequal length. It takes training or a dissonance between design beliefs and other beliefs or experiences to play the role that a ruler does in the visual case. Unless people are cued to “look again” at what initially makes perfect sense, they are not inclined to apply more sophisticated evaluative procedures. (shrink)