Why did Henri Bergson criticize Fechner’s Law?

Henri Bergson criticized Fechner’s Law because he believed it fundamentally falsified the nature of psychological experience.1

In his work Time and Free Will, Bergson argued that psychologists erred by attempting to quantify and measure internal states that are inherently qualitative. While Fechner’s Law sought to establish a calculable, mathematical relationship between the intensity of a physical stimulus and the resulting sensation, Bergson maintained that such efforts confused psychological facts with physical ones.12

For Bergson, human consciousness is defined by "duration"—a lived, continuous flow that cannot be broken down into discrete, numbered units without losing its true essence. By treating sensations as quantities that could be measured or numbered, Bergson argued that science imposed a spatialized, mechanistic framework onto the inner self, thereby misrepresenting the qualitative nature of human experience.13