What is more efficient--raising the air conditioner to 80F while not home or keeping steady at 72F?

My husband and I debate this question every summer. I think it is cheaper to raise the thermostat to 80F during the day when we are not home and cool it to 72F when we get home from work. He thinks it is cheaper to keep the thermostat steady at 72F all day so the AC doesn't have to work really hard to cool the house down. We have the same but opposite argument in the winter.