The Squirrel Around the Tree
How the Pragmatic Razor Dissolves Verbal Metaphysics
Returning from a solitary morning walk through the pine woods of the Adirondacks in the summer of 1898, William James found the rest of his mountain camping party locked in a ferocious philosophical argument around the clearing. The dispute centered on a simple mechanical puzzle. Suppose a live squirrel is clinging to one side of a large tree trunk, while a human observer stands on the opposite side of the tree. The man tries to catch sight of the squirrel by walking rapidly around the tree. No matter how fast he circles, however, the squirrel scrambles at the exact same angular speed on the opposite face of the bark. The tree trunk always remains squarely between them. Does the man go round the squirrel, or not?
The campers had divided into two equally stubborn factions of equal size, neither willing to yield an inch. Stepping in as a referee, James invoked the classical scholastic adage that whenever you meet a deadlocked contradiction, you must make a distinction. Which exact practical fact, he asked the campers, do you mean by the phrase going round the squirrel?
If you mean passing successively from the north of the animal to the east, then to the south, then to the west, and back to the north of him, then the man obviously does go round the squirrel. He occupies those four compass bearings in succession. Suppose instead that you mean standing first in front of the squirrel's nose, then to his right flank, then behind his tail, then to his left flank, and back in front of his nose. Under that definition, the man obviously does not go round him. The squirrel's compensating rotation keeps its belly pointed continuously toward the observer. Once the ambiguous verb was split into two distinct operational coordinate systems, both sides were simultaneously right and the controversy vanished on the spot.
On August 26, 1898, speaking before the Philosophical Union at the University of California, Berkeley, James used the campfire squirrel anecdote to introduce what he called the pragmatic method. He expanded that talk into his packed lectures at the Lowell Institute in Boston in November 1906 and Columbia University in January 1907. Reaching back to an overlooked January 1878 Popular Science Monthly essay (entitled How to Make Our Ideas Clear) by his friend Charles Sanders Peirce, James turned Peirce's laboratory rule of logic into a sharp philosophical razor for testing every metaphysical system.
Whenever two rival schools battle over an abstract distinction—whether the world is ultimately one or many, material or spiritual, fated or free—the pragmatist asks a single diagnostic question. What concrete difference will it make in anyone's actual future experience if Formula A is true rather than Formula B? In Lecture II of Pragmatism (1907), James stated the principle plainly: there can be no difference anywhere that does not make a difference elsewhere, and no distinction in abstract truth that does not express itself in a difference of concrete fact.
If two competing theories predict the exact same sensory observations and guide the exact same physical actions under every conceivable future test, then they are merely two verbal translations of the same thought. Theories cease to be cryptic riddles resting on the sphinx. They become working instruments whose truth-value—their experiential cash-value—consists in their power to lead an investigator smoothly from one part of concrete experience to another.
Within eighteen months of its May 1907 publication, Pragmatism went through seven printings. It turned a forgotten 1878 paper by Charles Sanders Peirce into the dominant philosophical movement of the twentieth-century Atlantic world.