premise: The 1948 SMU Mustangs football team represented the SMU Mustangs of Southern Methodist University during the 1948 college football season. Doak Walker was a junior when he won the Heisman Trophy. Doak established several other Southwest Conference records that still stand.
hypothesis: Several of the SMU Mustangs have won the Heisman Trophy.
reason: Doak Walker definitely won the Heisman and was a SMU Mustang but we do not have any other information indicating that other SMU Alums have won a Heisman.  I used the word "several" because it was in the text but indicated Doak's other records not other players.