Law of Diminishing Marginal Utility Utility refers to the amount of satisfaction a person gets from consumption of a certain item.and marginal utility refers to the addition made to total utility, we get after consuming one more unit. An individual's wants are unlimited in number yet each individual's want is satiable. Because of this, the more we have a commodity, the less we want to have more of it. This law state that as the amount consumed of a commodity increases, the utility derived by the consumer from the additional units, i.e marginal utility goes on decreasing.