This commentary focuses on Smithies’ views about self-knowledge. Specifically, I examine his case for the striking thesis that rational thinkers will know all their beliefs. I call this the ubiquity of self-knowledge thesis. Smithies’ case for this thesis is an important pillar of his larger project, as it bears on the nature of justification and our ability to fulfill the requirements of rationality. Section 1 outlines Smithies’ argument for the ubiquity of self-knowledge. Section 2 sets the stage for a detailed explication of his view by sketching an initial objection to that argument. Sections 3 and 4 respond to that objection on behalf of Smithies’ account, elucidating the distinctive positions on belief and justification that enable this response. Sections 5-7 raise some questions, namely: whether Smithies’ views about self-knowledge of beliefs provide a genuine competitor to other philosophers’ views on that issue; whether on his account justification is truly accessible to the thinker; how his account explains self-knowledge; and what his account implies about the situation of actual persons, who are not ideally rational.