通過考察各種懷疑論論證之後，葛雷克提供了一種被他稱為行動者可靠主義的德性知識論，其基本主張是知識是基於可靠秉性的真信念：一方面主張根據認知能力或德性來解釋知識來源的可靠性，另一方面主張根據主體的認知秉性來解釋主觀證成，揭示知識的主觀維度。隨後，他進一步引入信任這個概念來突顯秉性之於知識構成的作用，並把知識視為為主體對真信念的一種信任。行動者可靠主義有助於我們更好地理解懷疑論、知識的本質、結構和價值。

By examining varieties of skeptical arguments, John Greco provides a version of virtue epistemology named agent reliabilism, its basic idea is that knowledge is true belief based on reliable disposition: on the one hand, it explains the reliability of source of knowledge in terms of cognitive faculty or vitue; on the other hand, it explains subjective justification in terms of agent’s cognitive disposition, revealing the subjective dimension of knowledge. Furthermore, he introduces the notion of credit to make the role of agent’s disposition played in the constitution of knowledge salient, then defined knowledge as credit for true belief. In short, agent reliabilism helps us better understand skepticism and the nature, structure and value of knowledge.