Phrenology's frontal sinus problem: An insurmountable obstruction?

Whereas some of Gall's critics were quick to assail his organology as materialistic and fatalistic, others questioned his methods and scientific assumptions, especially his craniological tenets. The idea that the skull does not faithfully reflect the features of small, underlying brain areas was repeatedly brought up in the scientific debates. Critics pointed to the frontal sinuses above the eye orbits as evidence for the interior and exterior plates of the cranium not being in parallel-hence, for several or many phrenological organs being unknowable. This article traces the origins of the frontal sinus arguments and how Gall, Spurzheim, and later phrenologists responded to it. It reveals how the two sides fought and remained divided about the significance of the sinuses throughout the nineteenth century-that is, on whether the frontal sinus "problem" was an insurmountable obstacle or one that was merely an inconvenience.