Fichte's Jena Wissenschaftslehre is often thought to occupy a standpoint from which claims about what there really is, as opposed to claims about how we necessarily represent things to be, are metaphilosophically prohibited or methodologically precluded. In this chapter I argue that for Fichte a transcendental account of the necessary conditions for knowing supports an accordant understanding of the basic nature of being. These are linked by a reconception of the nature of rationality, and thus of rational justification, that Fichte's transcendental epistemology secures and which his ontology draws on and develops. In particular, his account of the nature of rationality issues in a distinctive form of nonevidentialism, according to which we possess unimpeachable rational grounds, albeit not narrowly evidential ones, for assent to certain metaphysical claims.