These are all old arguments, but since Mr Obama has put us in the mood over the birth control controversy, it is best to revisit them.
The dominant thinking is that morality should be decided by vote. This follows from the premise that there is no universal moral truth or authority. If there is no universal moral truth, then everybody gets to decide for himself what is moral and what is not. Conflicts will arise between individuals who decide oppositely or differently. Groups of individuals who think similarly must then band together: the group that is the largest is the one that dictates what is moral and what is immoral. It seems group membership will ever be in flux, thus what is moral and immoral will ever change. Morality is therefore not universal.
This fails immediately for at least two reasons. The first is obvious: in order for everybody to agree that a vote should decide what is moral, since the principle “everybody gets vote” is a moral principle, it is then a universal moral truth, which violates the first premise. If you say that everybody does not have to agree with the principle, then you have decided another universal truth: that morality should be decided by vote even if not all agree that morality should be decided by vote. Since the premise which began the argument thus false, it is not true that moral truth can be decided by a vote.
The second is related. Not everybody can vote so no morality can ever be decided upon. For instance, the very young and those that are senile or otherwise mentally incapacitated will not know how to vote. The principle states that all morality must be put to a vote: since not all can vote, no vote can ever take place. And even if all could, at this moment in time, actually vote, after some small amount of time (seconds) some will have died and others born. This changes the constituency and therefore implies a new vote should be taken every few seconds. If you say that voting should only take place at fixed intervals (say, a year) then this is another moral principle which is universal. Or if you say that representatives will vote for those unable, then this is another new moral principle; further, it is one that is universal, which also violates the first premise. Or you could say that those unable to vote do not get to decide what is best for them. This becomes yet another universal truth, etc. Again, moral truth cannot be decided by a vote.
It also fails because even if we accept that the universal moral principle that voting decided morality doesn’t count as violating the first premise, we have that after a vote has been taken on a particular moral question, the losers do not accept that the question just adopted is, in fact, moral. They may abide by the rules resulting from the moral vote, but that is different. Because a vote just decided that a thing is moral, and because we have decided that votes decide morality, that thing is moral period, so that nobody can change his mind about it. If they change their mind, they are saying that the vote did not in fact decide what was moral. Thus, morality by vote must remain static once every question has been put to the vote. This is so even if, as they certainly will, circumstances change. If a new vote is taken it is admitting the old vote did not decide what was moral.
If instead of a vote “might” is substituted then nothing changes. For instance, instead of a vote deciding what is moral and immoral, the strongest decide what is moral or immoral. Those against the strongest will be defeated by the strength of the strongest: the sword rules. Thus it was not morally wrong that the Nazis killed millions of Jews, Gypsies, and Poles because the Nazis were the strongest. It was not morally wrong that Stalin and Mao deliberately starved to death millions because these men (and their allies) were the strongest.
In any case, if we decide that might makes right, then we have decided a moral principle, one that is universally true to boot. Thus the first premise again fails because there exists at least one universal moral truth. It fails yet again when we consider that to decide that might makes right implies a vote, which brings us right back to the beginning. If you say that nobody has a choice and that might makes right is imposed upon us by the strong, then you have deduced yet another universal moral principle, namely that nobody has a choice. And so, etc.
These are the same arguments that show that Democracy, taken at its strict definition (everybody gets a vote), fails to be moral, incidentally. In order to work, Democracy must be modified to incorporate universal moral truths. Since we know, given the arguments above, that there are universal moral truths, it is up to us to discover what they are or suffer the consequences. This argument does not say that voting is not useful: but from it we infer that votes should be limited to subjects which are not universal moral truths, which we must accept as true period.