Bill Gates is a founder of Microsoft and the world's richest individual. Suppose Microsoft sells more software and Mr. Gates acquires another billion dollars in wealth

Simultaneously, suppose a burglar whose income is well below average broke into Bill Gates' house and stole a million dollars' worth of antiques. Using the "it's not fair if the rules aren't fair" approach to fairness, is Mr. Gates' acquisition of additional wealth fair? Is the (poor) thief's acquisition fair?

In order for Mr. Gates to become richer, Microsoft had to convince consumers to buy their products. The consumers' choices were voluntary. That is, the consumer engaged in a voluntary transaction with Microsoft and, as a result, Mr. Gates gained wealth. (And the consumers gained the software.) Because the exchange was voluntary, it is a fair exchange according to the "it's not fair if the rules aren't fair" approach. The burglar, however, did not engage in a voluntary transaction with Mr. Gates. Mr. Gates suffered an involuntary transaction with the burglar. Involuntary transactions violate the symmetry principle and hence the thievery is not fair according to the "rules" approach. Notice that the fairness has nothing to do with the incomes of Mr. Gates and the burglar; instead, fairness hinges on whether the transaction was voluntary.