Paper #64: Subtractive Co-Creativity: What Generative AI Erases, and Why That Matters

The dominant framing of human-AI co-creativity treats AI as a generator: a system that produces content for the human to receive, accept, edit, or reject. We argue that this productive default is the structural source of three failure modes the workshop call names (design fixation, output homogeneity across users, and authorship ambiguity), and that a complementary paradigm dissolves all three. We call this paradigm subtractive co-creativity: AI whose primary action is to remove content from a human input rather than to add. We develop a taxonomy of subtractive operations, advance three claims linking subtraction to each named failure mode, present a computational illustration on a public-domain artwork, and synthesize reflections from informal conversations with seven practicing artists. We close with a research agenda. The paper is positional; its contribution is conceptual.