His name is John Stuart Mill.

As for refutations, I am a bit lost on making any really good ones, because I don't see the persuasiveness in Utilitarianism. Utilitarianism is not a necessary conclusion or a fact, it is a normative argument, so I don't find its nature to be ultimately persuasive.

Utilitarianism is not something that handles a wide array of cases successfully. If your paradigm incorporates just one small belief, then you're not going to have a successful civilization for the reasons that happen out of not considering enough political possibilities.

Civilizations need to have a reasoning, capitulating, learning, problem-solving, defensive, team-value based essence to keep them afloat, otherwise they perish due to ineffective action. Monothematic civilizations make themselves susceptible to mass manipulation by creating collective personalities that make it easier for totalitarian bodies to gain control, and commit mass atrocities.

Now, I am not going to pretend I will know what a utilitarian society will look like, because that is basically admitting that the slippery slope fallacy is a means of observing the future, but I can say that it may not be very different from a movie, which should tell a person that it will not work inside the real world engine.

"He who knows only his own side of the case, knows little of that. His reasons may be good, and no one may have been able to refute them. But if he is equally unable to refute the reasons on the opposite side; if he does not so much as know what they are, he has no ground for preferring either opinion." Long time fan, as well

As a layman, I don't understand this philosophy. How can you maximize happiness in a group of people, when happiness means different things to different individuals within it? Also, is it the sum total of happiness at a given moment or is it cumulative over long periods of time? Specifically, a course of action might maximize happiness in the short term, but be highly distressing in the long term. One particular example is climate change.

That's an excellent question! And i suppose it would depend entirely on what actually entails the sacrifice. If this hypothetical Utilitarian society had such a divide that the sacrifice was costly, and left me with no happiness at all, then no I probably wouldn't. However I would like to think that a truly utilitarian society would have collective support structures and the ability to provide the basic neccessities. Were my sacrifice to be jobless with continued access to food, shelter, transportation, entertainment and safety then i probably would make that sacrifice. The goal is to try and achieve peak contentment for everyone and leave no one behind. I suppose Utilitarianism includes an acknowledgement that it is unlikely to achieve a perfect utopian life for all.

Well I liked Mill too when i discovered him in my freshman philosophy course. The problems with the "greatest good for the greatest number" are greed and discrimination. The "greatest number" won't all be happy with their level of good, and what about the rest of the people, who aren't included in the "greatest number? "The greatest good for the greatest number" is akin to "majority rules." The problem becomes for instance, when the majority decides that minority immigrants aren't allowed to be in the greatest number, or that it's ok to discriminate against the people who aren't in the greatest number, pick any minority. To me a society where the collective wealth of the community would be distributed evenly to the members would be a utilitarian society and each member works providing some good to the community. Problems arise when people are too ill or old to work or too lazy. A social security system could protect the elderly of course. A small society could pull it off--I don't think it's feasible for a larger society. Just my two cents.

Mill is the source of one of my favorite quotes although I realize that conservative was a political party in his context.

I did not mean that Conservatives are generally stupid; I meant, that stupid persons are generally Conservative. I believe that to be so obvious and undeniable a fact that I hardly think any hon. Gentleman will question it. --- John Stuart Mill

My biggest concern with Utilitarianism (and understand this is a statement from a lot of ignorance) is that I'm unaware of any human society that is both aware and altruistic enough to make it work. I'm afraid that our species won't be mature enough to operate at that level (maybe for all our allotted time?)

I prefer to work for the happiness and contentment for all ( leave no-one behind). But here is a question for you in return. Are you prepared to be one of those left behind in order to fufil the Utilitarian dream?

So if utilitarianism accepts that some may be less happy, how does it morally justify this?