MORAL REASONING, arguing what someone should or should not do, requires that we appeal to a standard, and prove or justify our specific moral claims in terms of that standard. The standard in ethics is moral truth—what we really ought to do—and that is determined by analysis and systematic reasoning. Our reason is only as good as its justification. Like philosophy in general, ethics attempts to train our reason or minds to formulate arguments seriously and "scientifically"; nonetheless, bad habits are often hard to break, and some forms of reasoning are often mistaken as legitimate. Here are some of the more common mistakes people make in their reasoning (the technical, logical term for these is "fallacies").

The Appeal to Subjectivity. Arguing that a feeling or action is moral or morally justified because all morality or moral claims are merely matters of opinion or personal preference. Moral truths differ from personal preferences and opinions—and the idea that these are all ultimately the same requires argumentation. I suspect that people using this sort of argument are often only attempting to dismiss or avoid having to face opposing claims than to actually argue for the truth of their own beliefs—this would be a nice labor saving device. Some of the more common forms this appeal takes:

• Moral principles are [or Morality is] completely subjective
• The morality of this is "true" for me, but not for someone else
• Everyone has their own beliefs and opinions [when used as a justification for someone’s action and not merely stated as a fact]
• All moral issues are private and personal
• Moral justification is all based on how a person sees things
• I cannot justify/judge morality for someone else
• Who am I to tell someone else what is right or wrong?
• Nobody can know that certain ways are the best ways of life

The Appeal to Tolerance [Liberalism]. This is the best way I know to put a slew of arguments that, like appeals to subjectivity, are more attempts to avoid having to justify one’s moral beliefs. Most of them are really appeals to subjectivity, yet the slight difference in these kinds of appeals is enough to give them a category of their own. These types of arguments attempt to avoid having to make any judgment on the morality of an action or feeling on the grounds that to do so is itself morally wrong, intolerant, or harmful to those involved. These concerns, even if sometimes real, are not sufficient reasons to discount making ethical distinctions or claims. These kinds of appeals often look like this:

• I’m personally opposed to this, but …
• If we say that n is wrong, then we are saying that people who do n and/or believe it is right are bad people
• If we say that n is wrong, then we will hurt of the feelings of people who do n and/or believe it is right
• If we say that n is wrong, then we are saying that we are better than the people who do n and/or believe it is right

The "Ethics Requires an Authority" Mistake. This is the mistaken view that morality must be dictated to us by some authority or other, or else it simply does not exist. The argument is again a trump-type argument, or "conversation ender," as there is often no ultimate authority or moral lawgiver, (or none that everyone can agree about) who authorizes and authenticates the moral rules. At the very least, no one of us can say that it’s us, and so were are tempted not to push the issue any more if others disagree with us. But the mistake is to personify something that shouldn’t be personified: in ethics we are not trying to name the person or thing that tells us what is right or wrong, but rather we are trying to investigate by thought and reflection, and come to understand what morality truly demands of us. These kinds of appeals often look like this:

• Who is to say what is morally right or wrong, good or bad?
• You can’t judge someone else
• You shouldn’t judge someone else
• No one should tell someone else how they should act
• Who am I to say that so-and-so (or such-and-such) is wrong?

The Appeal to Common Practice. Arguing that an action or feeling is moral or morally justified because it occurs frequently, i.e., everybody does it. What the majority of people think or do is not a valid basis for a moral truth. Quite simply, it is possible for the majority to be mistaken about correct ethical criteria and to approve unethical actions. This also mistakes a descriptive ethical thinking for prescriptive ethical thinking—we aren’t looking for what people, even the majority, actually believe, but how we should actually act.

The Appeal to Common Belief. Arguing that an action or feeling is moral or morally justifiable because many or most people believe it is morally justifiable. (This bases the justification on what people think, as opposed to the previous fallacy, which bases the justification on what people do.) Like what the majority of people do, what the majority of people happen to think is not a valid basis for moral truth. It is possible for the majority to be mistaken about correct ethical criteria and to approve unethical actions. A version of this mistake is to argue that something is justifiable because it is often done and people know about, or know about it and don’t complain about it.

Examples: action x is done all the time, and no one seems particularly bothered by it.

The Appeal to Tradition. Arguing that an action or feeling is moral or morally justified because it has the "force of custom"—that is, it is part of a society’s or culture’s traditions and constant practice. However, like majorities, traditions are not necessarily moral, and so this is not a reliable basis on which to base your claims. (Again, this is presenting descriptive thinking when prescriptive or normative thinking is called for.)