Rationality requires us to have certain propositional attitudes (beliefs, intentions, etc.) given certain other attitudes that we have. Carroll's Tortoise repeatedly shows up in this discussion. Following up on Brunero (Ethical Theory Moral Pract 8:557-569, 2005), I ask what Carroll-style considerations actually prove. This paper rejects two existing suggestions, and defends a third. © 2012 Springer Science+Business Media Dordrecht.