Rendering unto Cæsar the Things That Are Cæsar's: Complex Trust Models and Human Understanding

In this position paper we examine some of the aspects of trust models, deployment, use and ‘misuse,’ and present a manifesto for the application of computational trust in sociotechnical systems. Computational Trust formalizes the trust processes in humans in order to allow artificial systems to better make decisions or give better advice. This is because trust is flexible, readily understood, and relatively robust. Since its introduction in the early ’90s, it has gained in popularity because of these characteristics. However, what it has oftentimes lost is understandability. We argue that one of the original purposes of computational trust reasoning was the human element – the involvement of humans in the process of decision making for tools, importantly at the basic level of understanding why the tools made the decisions they did. The proliferation of ever more complex models may serve to increase the robustness of trust management in the face of attack, but does little to help mere humans either understand or, if necessary, intervene when the trust models fail or cannot arrive at a sensible decision.