In business law, past consideration is generally not considered valid because a contract requires a mutual exchange of promises or actions between the parties involved. Past consideration refers to actions or services that were performed before the contract was formed. Since these actions were not initially intended to be part of a contractual agreement, they lack the element of bargaining and mutual assent necessary for a valid contract. Business contracts typically require a meeting of the minds and consideration exchanged at the time of contract formation to ensure fairness and clarity in the agreement.