In Philip K. Dick's novel "Ubik," the phrase "I am alive, you are dead" encapsulates a central theme of existential uncertainty and the nature of reality. The characters navigate a world where life and death are not clearly defined, with technology blurring these lines. This creates a constant tension as they struggle to determine the truth of their existence and the nature of consciousness itself.

The narrative plays with the idea of perception, where the boundaries of life and death become increasingly tenuous. As the characters confront their own mortality and grapple with manipulation by external forces, the statement serves as a reminder of the fragility of human existence. Ultimately, "Ubik" challenges the reader to consider what it means to truly be alive and the implications of our reality.