The Representational Alignment Hypothesis: Evidence for and Consequences of Invariant Semantic Structure Across Embedding Modalities
There is growing evidence that independently trained AI systems come to represent the world in the same way. In other words, independently trained embeddings from text, vision, audio, and neural signals share an underlying geometry. We call this the Representational Alignment Hypothesis (RAH) and investigate evidence for and consequences of this claim. The evidence is of two kinds: (i) internal structure comparison techniques, such as representational similarity analysis and topological data analysis, reveal matching relational patterns across modalities without explicit mapping; and (ii) methods based on cross-modal embedding alignment, which learn mappings between representation spaces, show that simple linear transformations can bring different embedding spaces into close correspondence, suggesting near-isomorphism. Taken together, the evidence suggests that, even after controlling for trivial commonalities inherent in standard data preprocessing and embedding procedures, a robust structural correspondence persists, hinting at an underlying organizational principle. Some have argued that this result shows that the shared structure is getting at a fundamental, Platonic level of reality. We argue that this conclusion is unjustified. Moreover, we aim to give the idea an alternative philosophical home, rooted in contemporary metasemantics (i.e., theories of what makes a representation and what makes something meaningful) and responses to the symbol grounding problem. We conclude by considering the scope of the RAH and proposing new ways of distinguishing semantic structures that are genuinely invariant from those that inevitably arise due to the fact that all our data is generated under human-specific conditions on Earth.