Gauging Extraterrestrial Sentience & Intelligence: Substrate-Agnostic Metrics for ETI Beyond the Kardashev Scale

Traditional search methodologies for extraterrestrial intelligence (SETI) have largely focused on detecting technological signatures indicative of large-scale energy consumption, often relying on frameworks like the Kardashev Scale. However, the fundamental quest of SETI is for intelligence itself. Responding to the compelling arguments presented in Olev Vinn's "Technological Signatures of Super Civilizations" (2025, doi: 10.20944/preprints202506.1875.v1), which questions the universal applicability of such energy-centric paradigms, this article proposes that a more nuanced approach—grounded in substrate-agnostic metrics for sentience and cognition—is better aligned with SETI's core mission. By synthesizing two pivotal conceptual models—one focused on a species-agnostic understanding of cognition across all living organisms, and another proposing a substrate-agnostic framework for the emergence of sentience and consciousness via universal mechanisms—we construct a robust theoretical foundation for understanding mind and consciousness as emergent properties that transcend both species and material substrates. We argue that this integrated view is crucial for guiding the search for ETI, suggesting that truly advanced civilizations may not leave grand energetic signatures, but rather exhibit subtle, efficient, and ecologically harmonious cognitive and sentient expressions. This paradigm shift advocates for methodologies focused on detecting patterns of complex information integration and adaptive self-regulation, rather than solely brute energy.