Albert Casullo is a contemporary American epistemologist and professor at the University of Nebraska-Lincoln, best known for his sustained philosophical analysis of a priori knowledge and justification. His work systematically examines the nature, scope, and epistemic significance of the a priori/a posteriori distinction, challenging both traditional rationalist accounts and skeptical dismissals of the a priori. His monograph *A Priori Justification* (2003) is a central reference in the field.
Authored A Priori Justification (Oxford University Press, 2003), a systematic defense and analysis of the a priori
Argued that a priori and a posteriori justification are genuinely distinct epistemic categories, not merely pragmatic labels
Examined the relationship between a priority, necessity, and analyticity, resisting conflations common in the literature
Contributed to debates on whether empirical evidence can defeat or support a priori justified beliefs
Advanced the discussion of what makes a source of justification 'a priori' independent of experience