The principle rests on three assumptions: that each individual is the best judge of his or her own welfare; that social welfare is exclusively a function of individual welfare; and that if one individual's welfare is augmented, and nobody's is reduced, then social welfare has increased. Since these assumptions are empirically questionable, and probably embody value-judgements about well-being and satisfaction, they are somewhat controversial. It has also been argued that they constitute a rather weak basis for welfare judgements, since they explicitly forbid interpersonal comparisons, are concerned entirely with the subjective choices of individuals, and privilege the position occupied by the status quo (since any move from the status quo which was vetoed by one person would not be considered a Pareto-improvement). Most sociologists object to Paretian welfare economics because of its silence on the initial distribution of resources.
"Pareto principle." A Dictionary of Sociology. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/social-sciences/dictionaries-thesauruses-pictures-and-press-releases/pareto-principle
"Pareto principle." A Dictionary of Sociology. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/social-sciences/dictionaries-thesauruses-pictures-and-press-releases/pareto-principle