This post will consider the purpose of ethics and ethical theory, and in it I hope to explain the importance of consistency in ethical theory. The reason for this is that there is a potential objection to all of the ethical suggestions here, and many from ethicists across the ages: Why should my ethical beliefs be logical? An explanation of this is needed if there is to be any way to communicate with such people. The theory that I espouse may be somewhat surprising, but I hope that it can also be seen as illuminating.
I shall distinguish two aspects of ethical systems: Intuitions and logic. The first is the intuitive ethical judgements that we all have independently of any rational examination or logical underpinning. Now I emphasise that I am really referring to principles rather than assumptions. If someone merely assumes that something or wrong or right, it is more likely that this assumption can be challenged and overturned. Instead, by intuitions I more mean principles which are very unlikely to be changed no matter what arguments are given. An example might well be that all other things being equal, we should not kill. No matter what arguments are given to most people, they are not going to change their minds and think that killing is fine. This does not mean that these principles must be absolute. There can be numerous exceptions to when killing will be wrong, but none of these attack the basic principle itself. The more intuition based a system is, the more of these basic beliefs are held as unassailable and, in general, the more dogmatic a belief system will therefore be.
The second is logical principles derived from intuitions. This will use analogy and juxtaposition in order to make sense of the intuitions of the system, forming them into a coherent whole. Consistency is crucial here, as logic requires significant distinctions between cases if we are to alter the conclusions we reach. While intuitions are very difficult to displace since they are not based on logic, logic itself is always subject to contrary argument and reconsideration. So the more logic-based a system is, the more consistency it is likely to have to unify the intuitions.
I think that the interaction between these two forces can explain how logical systems grow up. In developing new theories, there are some conclusions that if reached I would refuse to accept, like if they made murder morally necessary. On the other hand, my stances on more complicated issues like abortion are the product of careful ethical reasoning and so could theoretically be overturned by logical argument. It is submitted that it makes more sense to have simpler principles as intuitions, since this can allow a greater basis for logic to work to fill in the gaps. If abortion being wrong was the principle, it would be difficult to apply this to many other cases - is it wrong to kill, wrong to visit a doctor, wrong to make choices etc? Instead, how most people actually work is by using the principle that it is wrong to kill and building up to the logical decision that abortion is wrong. We can often whittle down our strongest held views to a few irreducible intuitions and it is submitted that this is healthy.
However, our imaginary adversary might argue that his ethical system consists entirely of intuitions, and that he feels no need to be consistent. If this is true, then we are stumped - how can we convince this person of anything? This position would seem difficult to attack, but it is submitted that there is a good reason not to adopt something like it. This reason, the reason that it is better to use logic to create a consistent ethical theory as far as possible, is that it better allows us to achieve one (if not both) of the dual purposes of ethics.
Here is where my examination becomes controversial. It is usually thought that ethics and an ethical system have only one purpose, which I will put like this: It helps us to flesh out what we believe to be right and wrong from our dearest held intuitions. This means whittling down what we believe to intuitions and, for most of us, using logical consistency to apply these to other cases. This interaction between intuition and logic helps us to create an ethical system. However, the intuitionist will say that they can create an intuitive ethical theory just as well. If this is true, then we must look to the second purpose.
This second goal of ethics and ethical theories is to persuade other people of our ethical conclusions. When we force ourselves to take our intuitions to their logical conclusions however uncomfortable, we do so in order to give the necessary rationality to our ethics to use them to challenge the ethical systems of others. We develop our ethical beliefs not only for our own sakes, but in order to convert others.
This needs to be considered further, because it has rather surprising implications. If we imagine a world where everyone used purely intuition-based ethical systems, then no-one would be able to change the mind of anyone else through logical argument. This might work perfectly well for some people, but for most people it would be infuriating having no way to persuade people that their system was more valid. While it is important to be true to our own ethical standards, an important aspect of this is the possibility that this could encourage other people to accept our standards for themselves. Thus it is that people are not content with keeping their ethical views entirely private. Ethical debates are not about trying to find some abstract truth, but encouraging others to accept our views.
The only way that there can be meaningful ethical debate and ethical conversion is through logic. Of course, a lot of personal ethics is not logical but intuitive. However, in order to give ourselves the ethical ammunition to attack others, we limit the number of absolute intuitions we accept and piece together the rest of our systems with logical extrapolations. It is a trade-off, because while we now have the ability to attack other ethical theories, we have laid our ethics open to criticism and attack by others. Purely intuition-based ethicists cut themselves off from this world of ethical debate, unable to influence or be influenced. This gives their ethics a much narrower purpose. They merely know what they think right, not why. Furthermore, this damages the possibility of ethical co-operation when it comes to political and social ends. The more basic intuitions people have, the less likely they are to coincide. Almost everyone can agree that suffering is wrong, but it is harder to agree on how to react to poverty, and even more so when our only source is our own gut reactions. By reducing the number of intuitions we use, we find ourselves more able to coincide with others either by sharing intuitions and coming to agreements on how to logically build on this, or using different intuitions to come to the same substantive results (see my post on Block Theory). In short, having a more logic-based ethical theory bestows on us a greater ability to co-operate and influence the views of others. In a society such as ours, that becomes crucial.
The result is that consistency, a crucial element of logic, becomes a prerequisite to any successful ethical theory, measured by these yard-sticks. Attempting to cling on to one's beliefs by avoiding ethical debate has a number of disadvantages which suggest that it is for the benefit of everyone that we instead open up our beliefs for logical consideration.
Let us consider a worked example. Fred believes that abortion is wrong. Originally his position is entirely intuitionistic, and that suits him just fine. However, over time this comes to frustrate him. He is unable to persuade anyone else of his view and so feels that he is failing to do as much for his cause (which he views as right and good) as he could. He also has no luck in pushing for legislation outlawing abortion because no-one has any reason to agree with his views. Finally, Fred decides that action is necessary. He examines his intuition that abortion is wrong and through consideration, converts it into a logical inference from a number of other intuitions, primary among them being that killing is wrong. He finds that the more he reduces his intuitions down to less controversial intuitions plus logic, the better able he is able to argue with other people and in favour of his legislation. Even though his base intuitions may not be in accord with others, he is able to build up to conclusions with which others agree and finally to try to convince them of his ultimate conclusion. He may win a few converts or, potentially, he may have his logic challenged by those on the other side. He has taken the risk of challenge with the benefit of the chance to challenge. The risk has been worth it to convert others.
One might argue, however, that Fred has only let logic enter his system in the case of abortion, and only there because he cares enough. Anyone who tries to talk to him about climate change would have their pleas fall on deaf ears. However, it is not so simple. Once Fred has acknowledged the value of logic and consistency, this demands that it spread out across all his views. One may use a logical analogy to abortion in order to convince him of another view. Moreover, if he refuses to logically examine his beliefs in other areas Fred can be accused of hypocrisy, damaging his stance on abortion. Furthermore if Fred also cares about what he believes to be right, the introduction of logic in one area is more likely to make his think that he should logically examine all his beliefs. In short, although everyone has different issues about which they are passionate, this is likely to lead to the necessity of a defensible, consistent ethical view in all issues, or at least any brought up.
So to the hypothetical antagonist who claims that their system is entirely intuitionistic, the answer is simple. They may take that position and run with it, but they will never be able to persuade anyone on any ethical issue unless they allow in some element of logic to their views, and once that happens the process may not so easily be halted. The more forward thinking and efficient course is to open up all our ethical views to logical consideration, whittling down our intuitions as far as possible, so that we can face opposing views head on.