Hamer's uncle promised to pay him $10,000 if, when he went off to college, he didn't smoke, drink, cuss, gamble, or womanize. Hamer went to college and didn't do any of these during his 4 years but while he was at college, his uncle passed away, so it got complicated. Hamer said I didn't do anything that I had a legal right to do in those areas because I expected my $10,000 reward. This is an example of: