With all due respect to St. Peter's List post about Game of Thrones, which states that George RR Martin has no sense of virtue and good, only evil and sexuality, I disagree.
Granted, this is going to be about the current HBO show, and he was writing about the book. But I feel the show accurately captures Martin's style and has his blessing. So all of this could be more praise of showrunners David Benioff and D.B. Weiss, which is ok.
On the site, HHambrose says, "The literary trap that Martin does not avoid is that of modernity. One such pitfall is the inability for modernity to understand virtue. Almost every character in the series is an anti-hero. They are lesser evils fighting against greater evils. Those characters which do appear to be good speak of honor, not virtue. Inevitably, this leads to vague notions of morality based off naval gazing, i.e., seeking the “right” and “honorable” answer by self-searching and not external standards. However, even these vague moral heroes are naive, exploitable, and ultimately lost within a Machiavellian political power structure. It is a pit almost all modern literature falls into – modernity understands evil, but it does not understand good."
While correct in his assessment that fighting for honor is not the same as virtue, I disagree that every character in the series is an anti-hero. An anti-hero is someone who is typically a villain, but whom we are intended to root for because his actions tend towards the good. The classic example is Han Solo, a smuggler and thief who becomes the hero because he works to destroy the Empire. Richard B. Riddick is another, the man of immoral deeds tasked to save the universe.
Often confused with the anti-hero is the villain that we root for. Tony Soprano embodies this character, running the mob and killing people all for the purpose of advancing his business. If you want to make the argument for lack of virtue in their characters, The Sopranos is the best example, since each person in that show, almost without exception (FBI agents occasionally withstanding) were doing things according to a code and honor, but none of it was virtue in accordance with the Good.
Taking the fantasy world of Westeros, however, a few rules must be set down. First, until this current season, this was a polytheistic world. The old gods were worshiped, similar to ancient Rome and Greece, without any knowledge of the one true God. However, this does not excuse them from a sense of morality, since the Judeo-Christian moral system that is the most commonly followed takes its foundations from Natural Law, which in turn takes its turn from God himself, whether or not people believe in him or not. He is still there and still deciding what is right and just.
Game of Thrones, then, has the similar task that Aristotle and Plato had, to exist in a world of multiple gods and come to an understanding of good and evil that is not dependent on the god of the sun or the god of the harvest. Intellectualism is at the service of man, needing to understand the human condition using faith and reason. Faith in something unknown and reason to pass that understanding on to the people in a way that they will understand without proof.
Unfortunately we don't get a lot of learned intellectual discussion in Game of Thrones, and the sole proprietor of this is Tyrion Lannister. Born a dwarf and unable to fight in a world based on war, Tyrion had no choice to read the works of the ancient philosophers and come to understand the way the world works (very similar to the way that Octavian prepared himself to become Caesar Augustus and usher in the Pax Romana).
So the question is, does Tyrion understand virtue, or does he just understand politics? Most of the show is spent politicking and warring with other families, and aside from the Lannisters, there is no real sense of actual good vs. actual evil. This isn't The Fellowship preventing the rise of the Dark Lord and enslaving all of Middle Earth. We don't know why Aerys Targaryen was overthrown, and we don't know if Robert Baratheon and Ned Stark were justified in doing so. We do know, however, that government is at the service of the people, and the moment that government is no longer acting in the best interests of the people, they have a moral obligation to overthrow it.
Is that not virtue?
Is not the Night's Watch defending the Wall against the Wildlings and White Walkers virtuous? Putting their lives on the line so that people they do not know can live, sacrificing their well-being for others is a selfless act that could only be could virtuous. So isn't Jon Snow virtuous?
Ned Stark leaving his family because he could do more for the Seven Kingdoms as the King's Hand, again a selfless act, when he was happier in Winterfell is an understanding of actual Good.
It's easier to talk about evil and write about evil, because it is easier than good. It's why Luke Skywalker asked Yoda if the Dark Side was more powerful. Living a moral life is not easy. But in order to write about evil and in order to depict it, you have to have some understanding of good. There are no truly evil characters (except for Joffrey of course) and there are no truly good characters, because in the world, there is no one who is all good or all evil (except for Veena Sudd, of course).
So yes, the inhabitants of Westeros lean towards what is honorable. But what is honorable is oftentimes similar to what is just and good. We shouldn't be so quick to write off the notion of honor as something that is contrary to the moral law, and we shouldn't make it just a personal thing. Although they do not understand the One God, they were still created in his image, so when Robb Stark does something out of honor, he is understanding his inherent dignity and that he should behave in such a way that gives glory to that Unknown God.