The Tendai School had a more optimistic view of human potential than did the Hossō School. Tendai monks followed the Lotus Sūtra in arguing that all sentient beings could eventually attain Buddhahood. No beings were permanently denied Buddhahood. They also argued that the three vehicles did not lead to three separate ultimate goals. Rather, all sentient beings had only one ultimate spiritual goal, Buddhahood. Teachings leading the practitioner to arhathood or pratyekabuddhahood were only provisional teachings designed to encourage those with lesser faculties and lead them onward towards the single ultimate goal for all sentient beings, Buddhahood.

On the basis of these Tendai teachings, Saichō argued that only sūtras which presented provisional teachings contained claims that some people could attain Hinayāna goals but could never attain Buddhahood. The five types of human nature which the Hossō School had presented did not refer to seeds from the beginningless past, but to stages which a practitioner might attain and then transcend as he moved onward to higher goals. The five types of human nature were not determined by seeds which sentient beings possessed from the beginningless past, but by the obstacles which men had to overcome on their way to Buddhahood.