Expanding Explainability: From Explainable Artificial Intelligence to Explainable Hardware

The increasing opaqueness of AI and its growing influence on our digital society highlight the necessity for AI-based systems that are trustworthy, accountable, and fair. Previous research emphasizes explainability as a means to achieve these properties. In this paper, we argue that system explainability cannot be achieved without accounting for the underlying hardware on which all digital systems - including AI applications - are realized. As a remedy, we propose the concept of explainable hardware, and focus on chips - which are particularly relevant to current geopolitical discussions on (trustworthy) semiconductors. Inspired by previous work on Explainable Artificial Intelligence (XAI), we develop a hardware explainability framework by identifying relevant stakeholders, unifying existing approaches form hardware manufacturing under the notion of explainability, and discussing their usefulness to satisfy different stakeholders' needs. Our work lays the foundation for future work and structured debates on explainable hardware.