 Brian Weatherson offers an example involving a person he calls “Tamati”, a young mathematician who has a sudden strong conviction that there is no largest prime upon noticing that as primes get larger the gap between them also gets larger (2019: 125–26). Tamati believes that there is no largest prime on the basis of his strong conviction, and Weatherson explains how Tamati’s strong convictions about mathematical propositions are reliable. But, intuitively, Tamati is not justified in believing, nor does he know, that there is no largest prime without a proof that it’s true. So reliability is not sufficient for justification or knowledge even in the realm of the a priori.