Good
A long time ago, in a galaxy far, far away, the term "good" had something to do with virtue, and, even, dare I say it, holiness.
Good, like the term realist, has a classical, a modern, and a post-modern definition.
Jesus declared that only God is "good." Classical philosophers found such definitions too rigorous, however, and they proposed a variety of alternate definitions.
Thus, we have the followers of Epicurus, who believed that the greatest good was the maximization of pleasure, subject to the recognition that unfettered pursuit of pleasure would ultimately lead to unremitting pain, so, to them, maximizing pleasure involved things like tasting a fine wine, or marrying a beautiful and independently wealthy nymphomaniac who is also a master chef who loves to cook, not shooting heroine or visiting brothels.
Thus, we also have Stoics (followers of Zeno of Citium - not to be confused with Zeno of Elea his much smarter and more ancient compatriot), who believed that the greatest good was to live a life of right reason, which, in practice, meant staying out of trouble, and emotions, like desire, fear, pleasure and pain are to be avoided.
In this connection, both Plato and Aristotle took an approach that emphasized virtues such as courage, wisdom, confidence and self-discipline (though Aristotle, rather interestingly, took a Laffer curve approach to defining virtue which he termed "the golden mean"), thus taking a big step toward Christianity.
Like Plato and Aristotle, Stoics and Epicureans are virtue ethicists, though they disagreed on which virtues were more important to the good life. For Stoics, the chief virtue was caution, while for Epicureans, the chief virtue was good taste, with a nod to good manners.
Then, as everyone knows, the Christians came along and spoiled everything by calling self-sacrificial love the highest good.
So much for the classicists.
Moderns realized that the classicists had some grasp on the truth of what constituted the good. Thus, moderns believed in things like "a good wine," or "a good cigar," or "a good lay." They also recognized that things like cirrhosis, cancer and syphillis are bad, so they recognized it was possible to have too much of a good thing. Some even recognized that wealth, itself, could be a snare, and one of them, Nathaniel Hawthorne even composed a very moving version of the myth of King Midas. As a result, most moderns could be found somewhere along the Epicurean/Stoic morality spectrum. Most moderns called themselves Christians, and a few even became followers of Christ, while others preferred to think of themselves as being free thinkers.
It wasn't until the dawn of the Age of Aquarius that progressives realized the highest good was the diversity and flourishing of the biosphere, a corollary of which is what they call the maximization of human potential. In practice, this means that the only good use of energy is the absorbtion of natural sunlight, preferably through photosynthesis, though, for the time being, photovoltaics and the more crude solar panels (involving mere heat collection) can be permitted, and schemes like wind power, hydroelectricity and geo-thermal energy can be permitted in carefully controlled circumstances.
In that context, progressives realized that human population had to be minimized, so as to minimize its negative impact on the biosphere. Unfortunately, this objective tended to also threaten human biodiversity, natural evolution and (so some would say) ultimate human potential. (A few even recognized that minimizing population also had a negative impact on economic diversity, inventiveness and flourishing.) Thus progressives began to pursue eugenics, or human-directed evolution. Others took another approach, recognizing the potential for cybernetics and artificial life to maximize intelligence in the universe.
Thus, within the progressive movement, the eugenicists (followers of Francis Galton and Margaret Sanger) are the "conservatives," the Borgs (followers of Norbert Wiener and the Borg Queen) are the "liberals," and both like to quote the Jesuit free thinker (not, alas, an oxymoron in post-modern times), Teilhard de Chardin, to justify their opinions.
De Chardin invented a materialist version of Christ's claim (as articulated in Revelation 1:8) to being "the Alpha and the Omega" which he called "the Omega Point" (not to be confused with "The Omega Man"), and which might also be regarded as a materialist version of the Hindu/Buddhist concept of Enlightenment and the Theosophist concept of Ascension. This innovation gave new hope to materialist philosophers of all stripes. Now the primary argument is how to get there: pursue evolution of the human genome or pursue evolution of artificial intelligence.
Some people, of course, believe that aliens have already achieved Enlightenment, and they're ready to help us get there. The best known example of these is probably the cult known by the suggestive name Heaven's Gate. Others, like the Scientologists, believe we are descended from such aliens. Still others, like some New Agers, think of the enlightened end-game as a "higher self" attached to the material self. Interestingly, one might regard the Borg concept as a cross between the New Age concept of "higher self" and the belief that the Omega Point must be approached via the path of artificial intelligence.
All of which those of us who call ourselves Christians (and especially those of us who actually follow Christ) find a tad disturbing.
Then, too, the variety of thought which has infused contemplation of the good has set taxonomists spinning. Thus, I am motivated to propose the following criteria of analysis. If we regard "good" as a type of energy, we may begin to analyze philosophies of the good as endothermic or exothermic depending upon whether the emphasis is placed upon the individual receiving the good or providing the good. In addition, one may classify virtue philosophers according to whether they emphasize the role of intellect or will. Thirdly, one may classify philosophies according to whether the emphasis on what is received (or given) is placed upon physical pleasure or power. Fourthly, one may classify philosophies according to the role God plays, if any.
For example, one may classify the Epicures as endothermic and placing emphasis on the role of the intellect and pleasure. One may classify, on the other hand, Stoics as being largely mildly exothermic and placing emphasis on the role of the will, but also with a focus on pleasure, but the beginnings of a new focus on power. One may regard Plato and Aristotle as exotherms with a balanced consideration of intellect and will, an emphasis on power over pleasure (in an amalgam of Spartan and Athenian thought) and a new interest in the role of God. Likewise, one may consider Buddhists to be exothermic, but placing emphasis on the role of the intellect, with a nod to the role of the will in shaping attitude, and with a preference for power over pleasure, and, to clearly distinguish them from Hindus, forgetting about the role of God.
New Age "higher selfers," like the Epicures, can be classified as endothermic, and placing emphasis on the intellect, with the difference that New Agers prefer power over pleasure. Nietzscheans may be classified as pure endothermics who want all the intellect, will, power and pleasure and regard giving as disgustingly Christian and the question of God as a dead issue. By way of contrast, Christians may be classified as pure exothermics who want to develop intellect and will by channeling good from God to other fellow human beings, and also believe that, if they do so faithfully, they will ultimately reap maximum power and pleasure through participation in divinity.
There is, it may be said, a fifth dimension to consider in regard to the putative relationship with God. While Christians acknowledge an expectation of divination, actual followers of Christ believe (as per Philippians 2:5-8 - compare what Jesus says about reward in Matthew 5 and 6) that wanting to be like God in giving of oneself is prior to wanting to be like God in power and bliss. Indeed, a true follower of Christ would be happy to give of oneself for all eternity without any expectation of eternal reward if it were possible to love without hope or perhaps hope without expectation. Similarly, a Buddhist or Hindu will work long and hard on mastery of the expectation of gratification. Furthermore, the more selfish approach to this question is regarded by true Christians as Satanic. John Milton famously put in Satan's mouth (or would have if Satan had a mouth) the declaration "Better to reign in hell than to serve in heaven."
There is a sixth dimension to consider, which is the preferred connection of the good to the material or to the spiritual. I leave it as an exercise for the reader to classify the various philosophies according to this emphasis in defining the good.
Perhaps lastly (or seventhly, if there are more significant considerations), there is the dimension of ultimate time. By this I mean the timing of the expectation of receiving the good. Epicures and Nietzscheans are, by and large shall we say, not focused on delaying gratification, though both might be willing to suffer delay if the end reward is suitable. By contrast, the saints derive joy from serving God in this life or in the next, trusting in God's mercy for ultimate beatification and prepared to wait for it as long as God desires.