(1) Each state sets its drinking age at 21. (2) Drinking age became tied to highway funds somewhere along the way. ∴ (3)

(1) Drinking age became tied to highway funds somewhere along the way. (2) Were a state to lower their drinking age, they would also have to significantly raise taxes to offset the lost highway funds from the government. ∴ (3) Each state sets its drinking age at 21. (from 1-2)

(1) Drinking age became tied to highway funds somewhere along the way. (2) When drinking age is tied to highway funds, then, if a state lowers its drinking age below 21, then it will lose federal highway funds. ∴ (3) If a state lowers its drinking age below 21, then it will lose federal highway funds. (from 1-2) (4) If a state loses federal highway funds, then it would have to significantly raise taxes to offset the lost highway funds. ∴ (5) If a state lowers its drinking age below 21, then it would have to significantly raise taxes to offset the lost highway funds. (from 3-4) ∴ (6) States do not lower their drinking age below 21. (from 5) ∴ (7) Each state sets its drinking age at 21. (from 6)

(1) Drinking age became tied to highway funds somewhere along the way. (2) When drinking age is tied to highway funds, then, if a state lowers its drinking age below 21, then it will lose federal highway funds. ∴ (3) If a state lowers its drinking age below 21, then it will lose federal highway funds. (from 1-2) (4) If a state loses federal highway funds, then it would have to significantly raise taxes to offset the lost highway funds. ∴ (5) If a state lowers its drinking age below 21, then it would have to significantly raise taxes to offset the lost highway funds. (from 3-4) (6) States do not do what will make them have to significantly raise taxes. ∴ (7) States do not lower their drinking age below 21. (from 5-6) (8) If states do not lower their drinking age below 21, then they set their drinking age at 21. ∴ (9) States set their drinking age at 21. (from 7-8)