Geology, philosophy of

In the mid-1960s, geology underwent a conceptual revolution. Prior to that time, most geologists believed that the continents and oceans were fixed and permanent, the basic features of the earth’s crust. Subsequently they came to agree that the earth was covered by rigid plates, thin in relation to the earth’s diameter, in which the continents were embedded like logs in icebergs. It was the creation, movement and destruction of these plates that were responsible for the mid-ocean ridges, the areas of mountain building and earthquake activity, and the deep ocean trenches.

This conceptual revolution also marks a shift in the philosophy of geology. From the early nineteenth century, the chief philosophical question posed by geology was whether a historical science encountered special epistemic problems, a question that was usually answered by invoking the principle of uniformitarianism. In its strict form this stated that the only kind and intensities of causes that could be used to explain past geological phenomena were those that could be directly observed. Many sloppier formulations were invoked under the same name. Since the revolution, philosophers have turned to geology chiefly to use the revolution to exemplify or challenge one or another theory of scientific change.