Cassimatis's cognitive substrate hypothesis
The proposal by Nicholas Cassimatis that a small set of computational mechanisms - substrate-level operations such as focus of attention, unification, and constraint propagation - can explain the full range of human cognitive capabilities when combined and applied recursively. The hypothesis influenced the name and conceptual framing of the Cognitive Substrate project.
Nicholas Cassimatis developed the cognitive substrate hypothesis as a theoretical foundation for general intelligence: rather than requiring separate modules for language, vision, reasoning, and planning, a single set of low-level computational substrate operations can compose to produce all of these capabilities. The key operations Cassimatis identified - including attention focusing, unification of representations, and constraint propagation - are substrate-level in the sense that they are not themselves cognitive abilities but the mechanisms out of which cognitive abilities emerge. This stands in contrast to both purely modular architectures (where each capability is a separate system) and connectionist approaches (where capabilities emerge from undifferentiated distributed computation). The Cognitive Substrate project borrows the term 'substrate' in this spirit: the architecture aims to provide a small set of well-defined mechanisms (the cognitive loop, the memory substrate, the policy engine, the reinforcement pipeline) that compose to produce emergent general-purpose cognitive behavior.