I am going to write the same warning I have written to rationalist friends in relation to the Great Filter Hypothesis and almost everything on Overcoming Bias: BEWARE OF MODELS WITH NO CAUSAL COMPONENTS! I repeat: BEWARE NONCAUSAL MODELS!!! In fact, beware of nonconstructive mental models as well, while we're at it! Beware classical logic, for it is nonconstructive! Beware noncausal statistics, for it is noncausal and nonconstructive! All these models, when they contain true information, and accurately move that information from belief to belief in strict accordance with the actual laws of statistical inference, still often fail at containing coherent propositions to which belief-values are being assigned, and at corresponding to the real world.

Now apply the above warning to virtue ethics.

Now let's dissolve the above warning about virtue ethics and figure out what it really means anyway, since almost all of us real human beings use some amount of it.

It's not enough to say that human beings are not perfectly rational optimizers moving from terminal goals to subgoals to plans to realized actions back to terminal goals. We must also acknowledge that we are creatures of muscle and neural-net, and that the lower portions (ie: almost all) of our minds work via reinforcement, repetition, and habit, just as our muscles are built via repeated strain.

Keep in mind that anything you consciously espouse as a "terminal goal" is in fact a subgoal: people were not designed to complete a terminal goal and shut off.

Practicing virtue just means that I recognize the causal connection between my present self and future self, and optimize my future self for the broad set of goals I want to be able to accomplish, while also recognizing the correlations between myself and other people, and optimizing my present and future self to exploit those correlations for my own goals.

Because my true utility function is vast and complex and only semi-known to me, I have quite a lot of logical uncertainty over what subgoals it might generate for me in the future. However, I do know some actions I can take to make my future self better able to address a broad range of subgoals I believe my true utility function might generate, perhaps even any possible subgoal. The qualities created in my future self by those actions are virtues, and inculcating them in accordance with the design of my mind and body is virtue ethics.

As an example, I helped a friend move his heavy furniture from one apartment to another because I want to maintain the habit of loyalty and helpfulness to my friends (cue House Hufflepuff) for the sake of present and future friends, despite this particular friend being a total mooching douchebag. My present decision will change the distribution of my future decisions, so I need to choose for myself now and my potential future selves.

Not really that complicated, when you get past the philosophy-major stuff and look at yourself as a... let's call it, a naturalized human being, a body and soul together that are really just one thing.