John Stuart Mill

Again, Utility is often summarily stigmatized as an immoral doctrine by giving it the name of Expediency, and taking advantage of the popular use of that term to contrast it with Principle.

He who does any­thing be­cause it is the cus­tom, makes no choice. He gains no prac­tice either in dis­cern­ing or in de­sir­ing what is best. The men­tal and moral, like the mus­cu­lar powers, are im­proved only by be­ing used. The fac­ulties are called into no ex­er­cise by do­ing a thing merely be­cause oth­ers do it, no more than by be­liev­ing a thing only be­cause oth­ers be­lieve it. If the grounds of an opin­ion are not con­clus­ive to the per­son’s own reason, his reason can­not be strengthened, but is likely to be weakened by his ad­opt­ing it: and if the in­duce­ments to an act are not such as are con­sentan­eous to his own feel­ings and char­ac­ter (where af­fec­tion, or the rights of oth­ers, are not con­cerned), it is so much done to­wards ren­der­ing his feel­ings and char­ac­ter in­ert and tor­pid, in­stead of act­ive and en­er­getic.

He who lets the world, or his own por­tion of it, choose his plan of life for him, has no need of any other fac­ulty than the ape­like one of im­it­a­tion. He who chooses his plan for him­self, em­ploys all his fac­ulties. He must use ob­ser­va­tion to see, reas­on­ing and judg­ment to fore­see, activ­ity to gather ma­ter­i­als for de­cision, dis­crim­in­a­tion to de­cide, and when he has de­cided, firm­ness and self-con­trol to hold to his de­lib­er­ate de­cision.

To be held to ri­gid rules of justice for the sake of oth­ers, de­vel­ops the feel­ings and ca­pa­cit­ies which have the good of oth­ers for their ob­ject. But to be re­strained in things not af­fect­ing their good, by their mere dis­pleas­ure, de­vel­ops noth­ing valu­able, ex­cept such force of char­ac­ter as may un­fold it­self in res­ist­ing the re­straint. If ac­qui­esced in, it dulls and blunts the whole nature. To give any fair-play to the nature of each, it is es­sen­tial that dif­fer­ent per­sons should be al­lowed to lead dif­fer­ent lives.