Apparently, people who are aware of the relevant facts and experiencesin a belief forming situation, sometimes reasonably disagree aboutwhether to believe and why. This study argues that such disagreementsare possible, and that some purportedly fully informed reasonabledisagreements are genuine, including cases involving disagreement aboutwhich beliefs about God are reasonably taken to be properly basic, giventhe facts of religious diversity and cases in which phenomenologicallysimilar religious experiences properly ground a variety of religiousbeliefs. Drawing on the work of Alasdair MacIntyre, it also argues thatTradition-Based Perspectivalism roughly, the view that foundationalbeliefs about what is reasonable to believe and why, are tradition-basedand perspectival in nature, originating in and appropriately groundedonly from the perspective of some tradition of inquiry or other istrue, and that its truth provides additional support for the claim thatfully informed reasonable disagreement actually occurs.