Cranes vs. Skyhooks

In evolutionary science, what are "cranes" and "skyhooks"?

In the context of evolutionary science, "cranes" and "skyhooks" are metaphors coined by the philosopher Daniel Dennett to describe two different perspectives on the explanation of complexity and design in the natural world.

1. Cranes: In evolutionary biology, "cranes" refer to natural processes and mechanisms that gradually build and explain complex features or adaptations through the mechanism of natural selection. Cranes are metaphorical tools that elevate organisms and their traits from simpler forms to more complex and sophisticated ones over extended periods of time. They represent the cumulative effects of small, incremental changes and the power of selection acting on variation within populations. Examples of cranes in the evolutionary context include genetic mutations, genetic recombination, genetic drift, and other natural processes that lead to the gradual development of complex structures or traits.

2. Skyhooks: In contrast to cranes, "skyhooks" represent hypothetical or supernatural explanations that rely on extraordinary or unexplained forces to account for complexity or design in the natural world. Skyhooks imply a departure from purely naturalistic explanations and suggest the intervention of intelligent designers or external forces that transcend the laws of nature. They propose explanations based on magic, divine intervention, or other unverifiable and untestable concepts that do not follow the principles of scientific inquiry.

Dennett introduced these terms to highlight the distinction between scientific explanations rooted in natural processes and mechanisms (cranes) and non-scientific or pseudo-scientific explanations that invoke supernatural or unverifiable causes (skyhooks). The concept of cranes emphasizes the power of gradual, cumulative processes, such as natural selection, to explain the complexity and diversity of life on Earth, without requiring the invocation of supernatural or untestable explanations.