Last week, in my discussion of torture, I compared Same Harris' act-consequentialist moral theory with a desire-based theory that I employ in my writings.

Act-consequentialism holds that the right act is the act that produces the best consequences. Consequently, whenever torture produces the best consequences, it is the right action. In these circumstances, torture is not only permissible. It is obligatory. Failure to torture would count as a failure to do good.

The desire-based theory that I use asks whether we want to be surrounded by people who are so constituted that they could comfortably engage in torture. I argue that being comfortable with that type of cruelty makes people more of a threat in countless human actions outside of the torture chamber. Because these interactions are far more common then the opportunity to torture somebody to find the location of a hidden bomb (for example), comfort with torture does more harm than good. Correspondingly, creating a community in which people adverse to torture promotes an aversion to cruelty that leaves us all safer in our day-to-day interactions with our neighbors. To promote this aversion to cruelty, we condemn tolerance for torture.

In that earlier comparison between act-consequentialism and desire-based theories, one of the points that I touched on - and that Luke Hinsenkamp addressed in a comment - is the fact that act-consequentialist theories allow for only two moral categories when classifying actions. The act that produces the best consequences is morally obligatory, while all competing acts are morally prohibited. There is no room in act-consequentialism for non-obligatory permissions.

For example, when choosing what to eat for dinner, the act consequentialist demands that one create the meal that produces the greatest good for the greatest number - and morally condemns all other options. The same applies to choosing whom to marry, where to live, and what job to take.

Some act-consequentialists try to allow for non-obligatory permissions by pointing out that we never have full information on the consequences of our actions. In these cases, we can be forgiven for our failure to do the act that produces the best consequences. Instead, we may choose among options that, in our ignorance, are equally likely to produce the best consequences.

In contrast, desirism allows for a robust set of non-obligatory permissions that does not depend on ignorance. A person who is fully aware of all of the relevant facts would still have permission to pursue interests independent of the act-consequentialist best act. However, if those consequences caused too much harm, or an alternative produced a great deal of good, desirism would allow (and, in more extreme cases, require) that those consequences dictate on an agent's decision.

Here is a very simple example that illustrates the value of a diversity of desires.

When it comes to eating chicken, I prefer dark meat. My wife likes white meat. Consequently, whenever we have chicken, I get the dark meat pieces (legs and thighs), while she gets the white meat pieces (breast). It works out well. If it were the case that both of us preferred dark meat, or both of us preferred white meat, we would end up in a state of conflict. Hopefully, our marriage would be able to survive the resulting chicken wars. However, we do have reason to prefer our current state of diverse yet harmonious desires over a state of having identical desires.

In the population as a whole, we would face a lot more competition and conflict if everybody had a strong preference for exactly the same foods. We would run into a problem of diminishing marginal returns in producing the desired food. Competition would drive up costs. Poorer people would be forced to alternatives they do not like. However, a diversity of food preferences means that we have less conflict and competition. We can more efficiently grow a variety of foods in a variety of climates and conditions, leaving everybody better off than they would be if all of us had identical tastes.

To use another example, when it comes to the desires that motivate an agent to pursue a particular profession, we also have reasons to promote a diverse set of desires. If everybody had desires best fulfilled by being a doctor, we would all be competing for jobs as doctors. Some people may be forced to take jobs as pilots, school teachers, engineers, construction workers, and the like - but none of them would like it (which would aversely affect job performance). However, a diversity of desires means that some people like being a pilot, some like teaching, some like engineering, and some like construction work. Each person can, to a larger degree at least, seek a position that interests him or her. The harmonious interaction of these different people with their a diversity of desires works towards everybody's benefit.

This identifies two areas in which we do not have reason to use our social tools of praise and condemnation to promote the same desires in everybody. We have no reason to push all people into liking the same food or into the same profession and to condemn those whose desires lead them into some other food choices or other professions. In other words, this identifies two areas of non-obligatory permissions.

There may be some fine-tuning around the edges (e.g., human flesh is not on the menu). There may also be some value in weakly promoting some high-risk but necessary jobs over others (e.g., combat soldier, first responder) while condemning some other career options (corporate assassin). However, for the most part, food and career choices represent two out of many realms of non-obligatory permissions.

These realms of non-obligatory permissions do not arise from ignorance. They arise from the fact that there are areas where we have reason to promote a diversity of desires that work together. We have reason NOT to use our social tools of praise and condemnation to promote a universal desire or aversion. They arise from the recognition that morality is not primarily concerned with actions, but with using social tools to mold desires.