This principle of universal benefits can be contrasted with the chimera of "public good," practiced in non-free-market systems, in which the values of some individuals are sacrificed for the supposed "good of all." Equivalent phrases in common use include "public interest," "good of society," and "social utility." The notion of "public good" seems to derive from the naive utilitarianism of nineteenth-century thinkers such as J. S. Mill. In order to determine whether a policy serves the "public good," it is suggested, we must somehow measure personal utilities in terms of some quantitative common denominator (under this and alternative policies) and then sum these utilities across all members of society.

As has already been seen, however, there exists no scientific basis for such measurements—or even for believing that such measurements would be meaningful, even if we were omniscient. In the first place, personal utilities are ordinal rankings (p. 4.4:20). Such utilities, unlike cardinal measurements, cannot be "summed." To claim that "first plus second equals third," for instance, would be nonsensical. Furthermore, we have no basis for comparing utilities across multiple individuals, or even for assigning any meaning to any purported interpersonal comparisons (pp. 4.5:2-7). Despite their mathematical and pseudoscientific veneer, theories of "public interest" are neither scientific nor logically tenable.