Quality versus quantity in J.S. Mill

Can we know whether our actions are right by using J.S. Mill's theory? --

Happiness, being a quality, is not measurable . In other words, qualitative concepts such as happiness, cannot be quantified, or, for that matter, defined. The reasons for the unsuitability of happiness as a moral criterion should become clearer as we proceed.

Even if we assume happiness to be quantifiable, and even if we are convinced that some action produces happiness, we can never be sure whether it can produce the same balance of happiness against happiness in the long run. Smoking cigarettes may make people happy, but in the long run they may pay for all of that "happiness" with a greater "amount" of unhappiness. How is one to balance many years of mild happiness against a few years of intense unhappiness (due to lung cancer and so on) unless one evokes a "higher" criterion, for example, the intrinsic value of human life? If human life is valuable irrespective of the amount of happiness or unhappiness that it producers, then we can say that smoking cigarettes is bad because it cuts human life short, and not because it causes unhappiness. The problem is that Mill disregards the question of whether the means towards happiness are good or bad in themselves or not.

To remain within his own theory, however, Mill has to disregard the significance of means in any action, and stress only the end result of actions. An act can have a very "happy" consequence, without necessarily being a result of "happy" means. For instance, a feudal lord may drive his serfs night and day in order to produce the maximum possible amount of grains and so on, all the while telling them that it is all for their own eventual happiness. The latter may be true, but one may ask whether all the unhappiness during the year was worth the happiness gained at the end of the year. The question cannot be answered by mere reference to quantitative comparison of the two amounts of happiness and unhappiness, assuming such comparison to the possible. An adequate answer requires reference to such matters as human dignity and freedom, which are outside the Utilitarian sphere of definition.

Mill also does not make it clear how exceptions to moral rules are dealt with, that is, how does one know how widespread those exceptions are.

Mill's theory suffers not only from the inability to tell us what action is right, but also from internal inadequacies and inconsistencies. For instance, what would be the motive or incentive for a person, in cases where there is a conflict between personal and general happiness, to follow the Utilitarian principle and ignore his own happiness for the sake of general happiness? In other words, Mill does not deal with the apparent priority of self-interest in all human actions in a convincing way. The incentives mentioned by Mill, that is, the "external" motives of law and opinion, and the "internal" ones of education and reason, do not seem to be quite adequate to deal with the problem:
(a) If we need laws to act as incentives for good behaviour, then what is the use of a personal code of behaviour such as Utilitarianism?
(b) Opinions of others are by no means infallible, since on one hand they can be manipulated and altered to his own advantage by a sufficiently clever person, and on the other hand others do not know about a great deal of one's behaviour, and, of course, they are not able to form any opinions about them as a consequence.
(c) No matter how highly educated a person may be, he can probably never escape from the overwhelming influence of self-interest on his actions.
(d) Mill refuses to base his morality on subjective feeling about actions, and now he wants to base it on subjective reasoning processes. If the morality of actions can be rationally derived, then what is the use of general moral principles such as Utilitarianism?