Kohlberg's stages of moral development provides one perspective on this.
Kohlberb suggested that there are (at least) six levels of moral development. In his system, it is impossible to skip levels. Everybody starts at the level 1. Many adults end at level 4, while some progress to level 5 and a few progress to level 6.
Kohlberg called levels 1 and 2
pre-conventional morality. These levels are common in young children and probably also occur in non-human animals.
At these levels, the morality of actions tend to be judged by their direct consequences for the individual actor.
People at
stage one operate based on reward and punishment. If their actions are punished (or likely to be punished), they recognise that those action are "bad" (for them), and similarly they recognise acts that are praised or rewarded as "good" (for them). In general, the worse the punishment, the more "bad" the act is perceived to be. If other people are punished, they must be guilty of doing bad things.
At
stage two, people tend to weigh up the question of "what's in it for me?" when they act, then they do what they deem to be in their own best interest. Thus, if an act is convenient for the individual and not likely to result in punishment, it may be considered acceptable by the actor. At this stage, reciprocity is possible, on the basis that "I'll help you if you help me" or
quid pro quo.
Stages 3 and 4 are what Kohlberg referred to as
conventional morality. These stages are typically seen in adolescents and adults. Both stages look beyond the self, to consider the views and expectations of the wider society in which the actor lives. At these levels, the actor will tend to abide by societal norms, even where there are no immediate personal consequences for obediance or disobediance. However, at these levels, the rules and laws of society are seldom questioned. It is not a matter of whether a rule or law is fair, so much as whether it's a generally accepted behavioural convention in the society.
People at
stage three tend to try to live up to expectations in order to attract the approval of others in their society and to avoid disapproval. The consequences of one's actions are viewed in terms of being liked and well thought of in society. If one does the "wrong" thing, one will be disliked and potentially ostracised because one is "naughty". At this level, good intentions can be considered to be a valid excuse for bad behaviour.
At
stage four, the actor believes that it is important to obey the laws and social conventions in order to help to maintain a well-functioning society. At this level, it is not so much that the actor seeks the approval of others for his own benefit. Rather, he sees his own "good action" as beneficial to the greater society. "Bad" actions are bad because they tend to hurt the wider society, even when there is little or no chance of punishment for the actor. Everybody has an obligation to obey the law, because if a person does not obey it sets a bad example for the rest of the society, which might lead to a cascade of further law-breaking and eventually to a breakdown in the good functioning of society in general. Note, however, that even at this stage, the actor's personal morality is largely dictated by external forces.
Kohlberg referred to stages 5 and 6 as
post-conventional morality. At these level, actors realise that individuals are not homogeneous and are conceptually separate from society. In some cases, an individual's own perspective can legitimately take precedence over the view of the wider society in which the individual is embedded; in such cases it is legitimate to disobey societal rules that are inconsistent with "higher" principles. In fact, these levels are sometimes called the "principled" levels, for that reason.
Examples of "higher level" principles can include ideas such as basic human rights (e.g. the rights to life, freedom and justice).
Actors at the post-conventional level tend to view societal laws and rules as (often) useful mechanisms, but not as set-in-stone absolutes. The current ruleset might be deficient in terms of protecting human rights, for instance. At these levels, rules are not absolute dictates that should be obeyed without question. (Note that the post-conventional levels can sometimes be confusing to people who operate at the conventional levels, because those operating at conventional levels can sometimes confuse post-conventional decision making for pre-conventional morality - i.e. apparently "anti-social" behaviours can be seen as being driven by self-interest, similar to level 2 reasoning.)
At
stage five, actors recognise that the world is full of people with different opinions, rights and values, each with their own perspectives. Societies are formed when people make
social contracts that enable them to live in relate harmony with one another, mutually respecting one another's sometimes-differing interests. All laws can be tested against higher-order principles, and should be changed when they do not promote human flourishing or the "greater good". Societal change is best achieved through majority decision making and compromise. (Note: the idea of democracy is based on level 5 reasoning, although once suitable laws are in place the society can still function effectively without everybody operating at level 5.)
At
stage six, moral reasoning is based on
abstract reasoning using ideas about universal ethical principles. All laws - extant or proposed - are to be evaluated with high-level principles (i.e. those principles that can justifiably be claimed to be "universally" beneficial to all human beings) in mind. For example, laws should be fair to all. If they are not, then there is no obligation to obey them (insofar as they do not operate fairly); in some instances there might be a moral obligation to
disobey them.
Stage six reasoning has as a core operating principle that one must consider what it would like to be in the affected person's shoes, to consider what the practical impacts of a law or procedure would be on that person, in the light of universal ideals, considering how the affected person views the world and how one would be likely to act if they believed as that person believes. Kant's idea of the
categorical imperative, or Rawl's veil of ignorance are useful core concepts here.
There is some debate as to whether people - or how many people - operate consistently at level 6, in reality. Possibly, this could be more of a notion of how an "ideal moral actor" would operate, rather than a description of how actual people operate in the real world in a consistent way.
---
The question of the thread is "Can morality be taught?" If Kohlberg's system is an accurate description, then it seems that all human beings start from stage one. Some progress to subsequent stages. The only way they can do that is to learn about the social world in which they live. Getting to the last couple of stages probably requires further, specialised education in most cases, including suitable exposure to ideas about universal moral principles and similar.
