Profit and Pleasure

The modeling of Utilitarianism on Smith's system is based on the correlations of Pleasure with Profit, and Pain with Loss.  Now, the latter of each pair connotes a net quantity, i. e. an increase or decrease with respect to a prior condition.  But, beginning with Locke, a sense-datum, such as Pleasure or Pain, is a presupposition-less event.  Therefore, because Utilitarianism is an Empiricist doctrine, Bentham's and Mill's attempts to apply Empiricism to Smith's system are structurally flawed, at minimum.