A Mathematical Philosophy of Explanations in Mechanistic Interpretability -- The Strange Science Part I.i
Kola Ayonrinde, Louis Jaburi
TL;DR
The paper reframes neural network interpretability as a rigorous science, proposing the Explanatory View in which internal mechanisms provide causal, model-level explanations whose fidelity is measured by explanatory faithfulness. It formalizes Mechanistic Interpretability (MI) as producing Model-level, Ontic, Causal-Mechanistic, and Falsifiable explanations, and argues that generalisation reflects compressible structure that ur-explanations capture via representations. A central conjecture, the Principle of Explanatory Optimism, claims that the algorithmic generalisation of neural networks is human-understandable, justifying MI's pursuit despite value- and theory-ladenness. The work also delineates the limits of MI, especially in system-level contexts and low-abstraction explanations, and sketches a research agenda to formalize and test EO while emphasizing the role of explanatory virtues and human-computer interaction. Overall, the paper advocates for a realism-based, explanatory foundation for interpretability with potential implications for AI safety, ethics, and cognitive science.
Abstract
Mechanistic Interpretability aims to understand neural networks through causal explanations. We argue for the Explanatory View Hypothesis: that Mechanistic Interpretability research is a principled approach to understanding models because neural networks contain implicit explanations which can be extracted and understood. We hence show that Explanatory Faithfulness, an assessment of how well an explanation fits a model, is well-defined. We propose a definition of Mechanistic Interpretability (MI) as the practice of producing Model-level, Ontic, Causal-Mechanistic, and Falsifiable explanations of neural networks, allowing us to distinguish MI from other interpretability paradigms and detail MI's inherent limits. We formulate the Principle of Explanatory Optimism, a conjecture which we argue is a necessary precondition for the success of Mechanistic Interpretability.
