Yellow Peril, Z-Mouse and Spray Can

Rudolf Seising traced the intellectual lineage from Wiener's cybernetics to Lotfi Zadeh's development of fuzzy set theory. The talk's title referred to the "Yellow Peril," a nickname given to Wiener's notoriously dense, yellow-covered mathematical works. Seising explored the tension between Ernst Guillemin's idealized "perfect worlds" of precise mathematical models and the messy, uncertain reality that both Wiener and Zadeh sought to address.

Seising showed how Zadeh's key innovation was proposing membership degrees between 0 and 1, replacing the rigid binary categories of classical set theory with a continuous spectrum of belonging. This approach, which Seising characterized as a genuine generalization rather than a departure from classical mathematics, provided powerful new tools for reasoning about vagueness and uncertainty. The presentation illuminated how Wiener's comfort with imprecision and analog thinking directly influenced one of the most important mathematical frameworks of the late 20th century.