Taking Cuban's argument to its logical extreme, nothing can ever be guaranteed because a large asteroid could hit the earth and kill us all. I'm more likely to

Taking Cuban's argument to its logical extreme, nothing can ever be guaranteed because a large asteroid could hit the earth and kill us all. I'm more likely to believe that Amazon.com will honor its service guarantees than I am some no-name ecommerce company, and Amazon's guarantee is close enough to certainty that I don't question it. The probability of a promise being kept is somewhere between zero and one. Our job as buyers is to estimate that probability accurately enough to make rational decisions.