A common type of argument, used by neo-Aristotelians against the view of life as the standard of value, is examples of "hard cases", in which the action which Objectivists would regard as moral seems to conflict with survival.
Such arguments often posit situations relating to interpersonal ethics. A typical question is "why shouldn't you cheat, or initiate force, when you think you might not be caught"?
To a large extent, this type of question ignores the existential role, in survival, of acting on principle, as discussed above. As Rand demonstrated, the principles of honesty and non-initiation of force are crucial for survival [11].
I believe that is a conclusive argument against habitual dishonesty or initiation of force. Some more argument is needed to demonstrate why a single act of dishonesty or force is wrong; why, for example, having accepted the principle of honesty, a person should not act against it and act dishonestly just once, if he's really unlikely to be caught that one time. On this point, the psychological role of principles is central.
The existential role of principles to survival applies in the long run, and might not be negated by an isolated violation of the principle. In contrast, the role of principles in maintaining self-esteem is immediate, and depends on total consistency in following the principle. Once a person has formed his principles, and has fully understood their role in promoting his long-range survival, any violation of them will not only negate their contribution to maintaining his self-esteem, but will reverse it; these same principles will now lead him to evaluate his own actions --- and, consequently, his own person --- as unworthy. If the violation of the principle is isolated, and minor, then the damage to his self-esteem will be reversible; but his ability to act and achieve his goals will be impaired, at least in the short run, and he will have to spend significant time and energy on restoring his self-esteem. More commonly, he will protect his sense of self-esteem by evading his principles and rationalizing his action, thus making it likely that the violation of the principle will become habitual.
A person forming strong principles, then, has formed his own character so that violating these principles will cause him psychological harm, and so, in effect, created a situation in which even a single violation will be self-destructive. The alternative --- not forming these principles in the first place --- is even more self-destructive. When taking into account both man's existential and psychological requirements, it is clear that the only course consistent with long-range survival is forming the proper moral principles and consistently following them.
Other "hard cases" examples, which are sometimes brought up in arguments against the standard of survival, are examples of people who have acted againat Objectivist principles, and still survived to an old age.
The answer to this type of argument is that the Objectivist ethics is meant to help man survive in a world in which he is not omniscient; an action is judged, not by whether it contributed to one's survival in hindsight, but by whether it can rationally be expected to contribute to it --- which means, whether it follows the principles which generally, in the long run, contribute to man's survival.
It is possible for a person to act irrationally, causing damage to himself, without this actually shortening his life (just as a lion could lose its mane, without this actually shortening his life, if he then happens to never receive blows to the head). Damage is a threat to one's life; it can destroy one's life; but, in particular cases, it may turn out in hindsight that the threat was never actualized. This does not change the fact that the threat was there, and that, if survival is our standard, the person was wrong to inflict it on himself.
The most plausible of the "hard cases" arguments are examples of cases in which a person may, consistently with Objectivist principles, knowingly take an action which risks or destroys his physical survival. While such cases are very rare, they do exist. Some examples are: the example from Atlas Shrugged of John Galt, deciding to commit suicide if necessary to keep Dagny from being tortured; a person risking his life to escape a dictatorship; a person deciding to continue his chosen career even after finding out that it is unhealthy for him because of some medical condition; or a person who, consigned to a permanently vegetative state because of some illness or injury, decides to have the life-support machines disconnected.
In understanding such cases, we need to consider the importance for man's survival --- both existential and psychological, as discussed above --- of forming values. All of the above are cases in which a person is acting on values which, in general, support human survival; which, at the time that they were formed, were likely to help his survival; but which are now leading him to risk, or even certainly give up, his life.
The point discussed above regarding moral principles applies, even more strongly, to one's deepest concrete values. Once formed, acting to achieve these values becomes the basis of one's happiness. Acting in a way which clearly and strongly goes against these values will inevitably lead to the most profound unhappiness, losing the motivation to any further actions to sustain one's life, and quite likely dying soon in any case. The people in the above examples, therefore --- given their situations, and given the values they have already formed --- are not actually acting against their own survival; they are either choosing the action that has some chance of allowing them to survive, over the action which, by the psychological damage it will cause, will certainly kill them; or (in the cases of Galt and of the man turning off the life-support machines) are acting in a situation in which survival has become impossible.
The crucial point is that forming strongly held values might, in some rare cases, lead one to take actions leading to death; but in general, such strong values are much more likely to greatly enhance one's chances of survival, both by consistently guiding one's actions towards goals that help one's survival, and through their contribution to self-esteem and to happiness. Suppose a young person said to himself: "I don't want to find any work that I strongly care about; I don't want to develop any deep personal relationships with anyone; I don't want to develop any strong values, and this way I'll avoid the risk of facing any situations, in the future, in which my values will conflict with survival". I'm sure the reader has met many such people (though they probably were not quite as articulate as described here). Such a person will live his life with no purpose to guide his actions, and with no motivation for using his mind. Such a person's rational faculty will gradually deteriorate; he may be driven to various kinds of self-destructive activities to escape from the boredom of his life; and, in the long run, will be much less likely to survive.
Forming strong values, therefore, can be seen as involving a certain risk; but from the standard of survival, it is a risk well worth taking.