According to functionality doctrine, trademark protection cannot be granted for any feature that is essential to a product’s use or purpose, or that affects the product’s cost or quality. But because of the placebo effect, even seemingly inert names and symbols are imbued with precisely this kind of power. In fact, a wide variety of real- world phenomena challenge the prevailing understanding of trademark functionality, from the social uses of high-fashion marks to the cost reductions enabled by certification marks. More fundamentally, a valuable trademark of any kind should act to reduce search costs for consumers and improve quality through reputation. And yet, rather than leading to invalidation, all of these well-documented functionalities are apparently tolerated by trademark law—sometimes merely ignored, but often celebrated explicitly.