PATHOLOGICAL GEOLOGY: PERCIVAL LOWELL’S MARTIAN CANALS

At the end of the nineteenth and beginning of the twentieth centuries, the American public thrilled to astronomer Percival Lowell’s images and books purporting to document his observations of canals on the surface of Mars. Lowell considered astronomy to encompass planetology, which he defined as the study of the evolutionary history of planets, including Earth, as products of “cosmic causes that have been at work” requiring “cosmic laws to explain them.” For Lowell, geology was a mere “local science” necessarily restricted to dealing with events on Earth that were already prescribed by “cosmic occasioning” over which “astronomic cause presides.” He considered geologists to be a lower class of scientists whose research is “limited to the accumulation of facts.” These views provide insight into why, when Lowell actually researched the planetary geology of Mars, the result was pathological science. (As defined by chemist Irving Langmuir, pathological science occurs when researchers are tricked into false results by various factors, including wishful data interpretation.) Lowell’s Martian canals claims and his closely related theories of planetary evolution illustrate how the abductive (retroductive) mode of reasoning that is central to geological inquiry can be misapplied by someone disdainful of its logic, ignorant of its methods, and dismissive of the fallibilism that is essential in all valid scientific reasoning. Lowell’s books on Martian canals were severely criticized by prominent scientists of his day, including the geologists Eliot Blackwelder (Univ. Wisconsin) and Joseph Barrell (Yale). Moreover, in 1905, when geologist T. C. Chamberlin and astronomer F. R. Moulton collaboratively developed a more productive, alternative approach to planetology, it drew severe criticism from Lowell. Though the Mars canals debate ended with Lowell’s death in 1916, vestiges of the geology-versus-astronomy philosophical divide persist to the present day.