The national obsession with head size and shape also infected daily conversation. Many modern phrases trace their roots to phrenology, including “highbrow” and “lowbrow,” “well rounded,” and “shrink” (as in “shrinking” certain undesirable qualities). “Getting your head examined” also has phrenological roots. Though generally considered an insult today, in the past, it was just what most people wanted. By the mid-19th century, the Fowlers’ publications could be found all over the country, and phrenological ideas had become a part of everyday conversation.
Still, the field had many skeptics. From its earliest days in Europe, phrenology faced plenty of criticism, mostly from doctors, scientists, religious leaders, and politicians. The Austrian government ordered Gall to stop lecturing in 1801 for fear that his talks would cause people to “lose their heads” and become materialists, believing only in the truths written on their skulls rather than those of God. Gall soon fled Vienna for France, but there, too, he faced a backlash that threatened his credibility.
French scientist Marie-Jean-Pierre Flourens became one of Gall’s most powerful adversaries. Flourens systematically tested Gall’s theories on animals, removing portions of the brains of dogs, rabbits, and birds to examine how the remaining sections functioned. His experiments led him to conclude that Gall was wrong: that the brain acted as a whole unit and not as discrete parts. Damage to one area caused other parts to take over and perform the same function. He published his findings in two explosive exposes.
In Washington, D.C., Professor Thomas Sewell also rejected phrenology as a method for understanding the brain. He argued that brain injuries rarely affected bodily function in the way predicted by phrenology. Moreover, Sewell argued that the brain couldn't possibly be measured from the skull alone. Harvard professor Oliver Wendell Holmes took a similar line of criticism. He compared the skull to a safe that enclosed contents—the brain—unknowable from the outside:
The walls of the head are double, with a great air-chamber between them, over the smallest and most closely crowded “organs.” Can you tell how much money there is in a safe, which also has thick double walls, by kneading its knobs with your fingers? So when a man fumbles about my forehead, and talks about the organs of Individuality, Size, etc., I trust him as much as I should if he felt the outside of my strongbox and told me that there was a five-dollar or a ten-dollar bill under this or that particular rivet.
Holmes did not state outright that phrenology was wrong, but rather that there was no way to prove that it was right either, which made its status as a true science questionable.
By the 20th century, phrenology had mostly lost its scientific authority and much of its popular appeal. A few diehards, among them the children and grandchildren of the Fowlers, still practiced. The progress of medical science offered new and better tools for understanding the brain. To many Americans, phrenology now seemed old-fashioned and ridiculous.