II. Moral Reasoning: Principles and Problems


We have seen in the previous chapter that ethicists attempt to move beyond the simple acceptance of ethical viewpoints--they attempt to offer reasons that recommend the general adoption of these viewpoints.  The process whereby a given belief or judgment is supported by reasons that recommend its general adoption is known as "justification."  Moral reasoning is simply one form of justification.  In this chapter, we will consider first some basic terms and concepts that apply to all forms of justification, and then look more closely at special principles and common errors that pertain especially to moral justification.

Justification and Logic

Ethics, as any form of rational inquiry, is concerned with establishing beliefs or judgments that can be justified in an objective manner. The rational justification of a belief or judgment is expressed in the form of an argument. (Common synonyms for "argument" are "proof" or "demonstration.")  In this context, the term "argument" does not refer, as it commonly does in ordinary discourse, to a debate or disagreement between people (although arguments can and commonly do enter into debates and disagreements), but rather refers to the process by which reasons are offered that recommend the acceptance of a given belief as true. Logic is the study of the fundamental principles that enter into the determination of the quality of an argument: the extent to which the reasons offered in support of a belief actually do provide support for the belief. We will consider here some basic terminology that applies in analyzing the structure of arguments, and determining their quality.

The Structure of Arguments

Any argument can be analyzed into two basic elements: (1) a conclusion, which is a statement that expresses the belief which is supported by the argument; and (2) one or more premises, statements (or propositions) which express the reason or reasons offered in support of the claim that the conclusion is true. For example, consider the following argument.
It is clear that the world had no beginning, since if it did, there would have been a first moment before which there was no other moment, but every moment is preceded by some previous moment.
In this argument, the conclusion is "It is clear that the world had no beginning," and two premises are offered in support of this conclusion: (1) "if it did . . . other moment," and (2) "every moment . . . previous moment." The premises are indicated by the word "since." Other common premise indicators are the words and phrases "because," "for," "for the reason that," and "on account of the fact that." The phrase "It is clear that" indicates the conclusion. Other words or phrases that indicate conclusions are the following: "therefore," "thus," "so," "it follows that," and "we can conclude that." At times when arguments are offered in ordinary discourse, premise or conclusion indicators are not used. When this happens, identifying the conclusion requires that we determine the statement in the argument that the author of the argument is trying to support.
    It can be helpful to make the structure of an argument explicit when writing it out. When this is done, the convention in logic is to write out each premise as a separate statement, often numbered or lettered, followed by the conclusion. Sometimes a line is drawn between the premise(s) and conclusion so that their status in the argument is clear. If we do this with the argument above, we get the following: Notice that when we put the argument in this form, the premise and conclusion indicators can be removed. For clarity's sake, we also interpreted the phrase "if it did" in the original expression of the argument in terms of its antecedent "the world had a beginning" when restating the first premise. Other conventions apply in some forms of logic that determine the order in which the premises are written, but we will not consider these conventions here. At times in this course we will express arguments in this conventional form to make the logical relationship between the premises and the conclusion clear.

The Evaluation of Arguments

There are two standards by which the logical quality of an argument (the degree to which the premises support the conclusion) can be determined: deductive and inductive.


The deductive standards are called validity and soundness. An argument is valid if on the assumption that the premises are true, the conclusion must be true (cannot be false).  An argument is invalid if on the assumption that the premises are true, the conclusion still could be false. For example, consider the following argument. This argument is deductively valid, which is to say that if premises (1) and (2) were true, the conclusion would have to be true. Notice that the fact that premise (2) is false does not effect the validity of the argument, because validity has nothing to do with the actual truth or falsity of the premises or the conclusion.
    The fact that valid reasoning is not dependent on the actual truth of the premises of an argument allows for the possibility of hypothetical reasoning: by assuming that something is the case (that is, by making a hypothesis), we can discover what also must be the case. For example, we can assume that the moon is made of green cheese and discover that this implies that it is edible.  Hypothetical reasoning is a crucial tool in ethics as well as the natural sciences and mathematics.
    Of course, if we want our deductions to provide real understanding, the premises that we start with must be true. When a deductively valid argument has premises that are actually true, it is called a sound argument.


An argument may fail to meet the standard of deductive validity and yet still be a useful argument in that the premises provide some support for the conclusion. For example, no one could reasonably deny that the following argument provides some support for its conclusion. This argument is deductively invalid, but by another standard of quality, the inductive standard, it is quite a good argument. The inductive standard of quality is known as strength. A strong argument shows that the conclusion is highly likely to be true given the truth of the premises. In other words, the premises provide strong support for the conclusion. A weak argument, on the other hand, would provide very little support for its conclusion. Notice that whereas the deductive standard defines only two values in assessing the quality of an argument--either an argument is valid or invalid--the inductive standard defines a continuum of values, since there is a whole spectrum of degrees to which the premises of an argument support an argument, from very strong to very weak arguments.

The Nature of Moral Reasoning

Like any form of reasoning, moral reasoning attempts to establish that some proposition or claim (a conclusion) is true on the basis of premises which support its truth. The essential difference between moral reasoning and other forms of reasoning is that the conclusion supported by the reasoning is a moral judgment. There are basically two forms of moral reasoning: (1) reasoning that attempts to demonstrate the truth of some general moral principle, and (2) reasoning that attempts to establish the truth of particular moral claims on the basis of general ethical principles. We will consider some examples of the first form of moral reasoning when we study theoretical normative ethics and consider some arguments offered by modern ethicists in support of a variety of ethical theories. But for the most part we will be considering moral reasoning of the second type, a form of reasoning sometimes called "moral deliberation."

Moral Arguments

Joan Callahan offers a good account of the basic structure of moral arguments.1 One premise of such an argument will state a general moral principle (GMP) that provides the normative criterion that is used by the argument. A second premise states a factual claim or claims (FC), and the conclusion states a derivative moral judgment (DMJ) that is more specific in application than the principle stated in the first premise. This structure is deductive in nature, since if the GMP is true, and the FC correctly applies the moral criterion of the the GMP, then the conclusion must be accepted. The general form of the argument can be represented in this fashion: The properties cited constitute the moral criterion defined by the principle. For example, the principle of honesty states that any statement of a falsehood that is offered with the intention to deceive is wrong. The properties of the action in this case are that the action is a statement, that the statement is false, and the action is intended by the agent to deceive someone.
    Although this structure seems quite simple, moral reasoning can be quite complex, involving not one but several moral principles, a variety of factual claims, and at times a string of arguments that leads to the final conclusion. All of these elements can be placed in a variety of orders, making it difficult to sort out. Consider this argument, for example, from John Stuart Mill's On Liberty. In this argument, the conclusion is stated first: that opinions may be sanctioned by blame or punishment when their expression under particular circumstances constitutes "a positive instigation to some mischievous act," or, in other words, an incitement to others to cause harm. The general moral principle of the argument is stated last: that actions which without justification do harm to others may and in some cases should be controlled by "the unfavorable sentiments" (i.e., disapproval) or "active interference," such as punishment. The factual link between the general moral principle and the derived moral judgment is the claim that expressing opinions under certain circumstances can inflame peoples' passions, which can lead to harm. But notice that Mill doesn't simply state this claim, but offers an example that he believes makes the point. This example is stated, furthermore, in the context of  a more specific moral argument applied to this example, an argument that uses the same general moral principle as the earlier argument. Thus Mill's statement "many justly incur punishment when delivered orally to an excited mob assembled before the house of a corn-dealer" can be analyzed in the context as the following moral argument (I've restated some of Mill's claims for the sake of clarity). Thus Mill's argument is complex, interweaving two arguments--one main argument, and a more specific argument applying the same general moral principle to a particular case.
    Analyzing and understanding moral arguments can, then, be a complicated affair. Some rules of thumb apply to the interpretation of moral arguments offered in discursive form.

Formal Principles of Moral Reasoning

There are many criteria that can be applied to assess the validity of moral reasoning, but there are two formal principles of moral reasoning that are particularly important and fundamental. These principles are "formal" in the sense that they concern the form or structure of moral reasoning rather than its content.
    The first of these principles is quite easily grasped from the analysis of the structure of moral arguments that we just considered.  All moral arguments must include both a statement of a general moral principle (a normative claim) and a statement of relevant facts (descriptive claims) if they are to be valid.  Put in another way, no derivative moral judgment follows from simply a description of facts.  This principle of moral reasoning was first clearly stated by an eighteenth century British philosopher by the name of David Hume.  Hume noted that there is a logical barrier to deriving claims concerning how we ought to act from descriptive claims concerning the way things are.  This barrier has come to be known as the "is/ought gap" in ethical thought.  One cannot validly claim that one, for example, ought to respect others merely on the basis of the factual claim that respecting others assures that they will treat us well.  We must add some normative standard to the effect that being well-treated by others is a good that we ought to seek.  The naturalistic fallacy considered below is one common way that this principle of moral reasoning is not observed.
    A second basic principle of moral reasoning is that such reasoning must be consistent: we cannot hold inconsistent moral positions in different situations.  This principle of moral reasoning is typically called "the principle of universalizability."  This principle can be stated as follows: This principle simply states that rational moral judgment must be consistent over all cases of actions that are similar to one another in respects that are relevant to moral judgment.  If, for example, one judges that it is wrong to cause other human beings great physical pain because pain is inherently bad, then one is committed to saying that it would be equally wrong to cause nonhuman animals great pain for the same reason.  If one judges that this is wrong in the case of human beings but permissible in the case of animals, and one cannot spell out how human pain is in a relevant way different from animal pain, then one's moral position is inconsistent and thus fundamentally irrational.
    The principle of universalizability is the basis of all moral reasoning. If this principle were not accepted, then moral reasoning would be impossible.  Could we reject this principle?  To do so would be to, in effect, deny that any moral judgment is more correct or true than any other, that there are no moral truths that can be accepted on rational grounds, and it seems quite impossible for us in a practical sense to believe this, as we saw in the discussion of ethical relativism in the previous chapter.  When other people do harm to us, or treat us in ways that accord us little respect as human beings, it seems quite impossible for us to simply shrug our shoulders and say "I have no reason to complain about this."  Even if we might question the principle of universalizability in theory, we all accept it in practice.

Fallacies of Moral Reasoning

A fallacy is an error in reasoning which prevents the reasons offered for accepting a certain conclusion from providing any real support for the claim that the conclusion is true.  In other words, a fallacious argument seems to offer reasons for accepting a conclusion as true, but on closer examination it becomes clear that the argument provides no good reason for doing this.  Logicians have identified many such fallacies--fallacies that arise quite commonly in debates and discussions of important issues.  Below, I will concentrate on a number of fallacies that arise most commonly in these discussions.

The Naturalistic Fallacy

The naturalistic fallacy is a result of not recognizing the significance of the distinction between normative and descriptive claims, and the necessity of the former in any cogent ethical argument.  The fallacy is committed when someone offers simply a description of "natural" facts as the basis for accepting a derivative moral judgment, without citing normative principles as well.  Such an argument is never cogent, since descriptions of facts never imply the truth of some moral judgment.  Consider, for example, this moral argument against disciplining children. The conclusion is a moral judgment, "punishing a child for some wrongdoing is never right," and in support of this conclusion a fact is cited, "punishment causes emotional pain."   The fact itself, even if we admit that it is always true, does not show that the conclusion is true.  The argument is based on an unarticulated normative claim, namely "Causing emotion pain is never right."  But once this claim is made explicit, a number of questions are raised which the original argument doesn't address: "Is emotional pain always bad?" "Isn't it the case that in some circumstances linking a punishment with wrongdoing can inhibit wrongdoing in the future?"  Since the original argument doesn't state the normative claim, it avoids raising some very important issues that must be addressed in order to evaluate the truth of the conclusion.
    One recent moral debate where the naturalistic fallacy is often encountered is in the abortion debate.  Consider these parallel arguments, one supporting pro-choice, the other supporting the immorality of abortions in the first trimester.
Pro-choice: Science has shown that the fetus in the first trimester lacks the ability to u, v, w, therefore it is morally permissible to abort a fetus in the first trimester.

Antiabortion: Science has shown that the fetus in the first trimester has the ability to x, y, z, therefore it is immoral to abort a fetus in the first trimester.

Neither of these arguments support their conclusions, since the facts that science uncovers concerning the abilities or inabilities of a first trimester fetus simply do not, by themselves, imply that abortion is right or wrong.  What is needed, here, is some consideration of the normative question of what sorts of abilities a living thing must have for it to be regarded in a moral sense to be what in ethics is called a "person," someone who is a holder of the right to life.  Thus, with respect to the first argument, a further premise is required that says "Everyone who has the ability to x, y, z, is in a moral sense a person," and the second argument requires a premise that says "Everyone who lacks the ability to u, v, w, is not in a moral sense a person."

Other examples of the naturalistic fallacy:

Tu Quoque (pron. too kwokwee; Latin for "you also")

This fallacy is a quite familiar one, often used by those who are attempting to absolve themselves of responsibility for moral wrongdoing.  This fallacy is committed when someone suggests that a certain action is not morally objectionable because others have done the same or similar things.  Typically the person who offers this argument is someone who has been accused of moral wrongdoing, and it is directed against that person's accusers, as if to say "you cannot accuse me of wrongdoing, since you are guilty of wrongdoing as well."  The argument is clearly fallacious, since the question of whether others are guilty of wrongdoing is irrelevant to the question of the accused person's responsibility for moral wrongdoing: as the old saying goes "two wrongs do not make a right."

Examples of tu quoque arguments:

Moral Conventionalism

Children often attempt to convince their parents that there is nothing wrong with something that they have done or wish to do because "all the kids are doing it."  This is an instance of a very familiar fallacy known as "moral conventionalism."  More generally, one commits this fallacy if one suggests that common or conventional practices in society provide the normative standard by which the moral status of actions should be judged, thereby suggesting that if people in one's society commonly perform some action, the action is morally permissible.  One problem with moral conventionalism is that often it is committed with exaggerated claims concerning the prevalence of the action that is adjudged to be morally permissible.  When children, for example, say "all the kids are doing it," this often is quite untrue.  But there is a deeper logical problem with moral conventionalism--it implies that "common practices" within a given social group cannot be morally impermissible, which on the face of it is clearly untrue.  If this were the case, then the practice of slavery in the southern states of the United States prior to the Emancipation Proclamation would have been morally permissible simply because it was common practice--an absurd suggestion.

Examples of moral conventionalism:

Moral Legalism

A fallacy that is closely associated with moral conventionalism is moral legalism.  Whereas moral conventionalism appeals to common or conventional practices as a normative standard, moral legalism appeals to laws of the state or, more generally, any codes of conduct that are accepted within some social group.  Thus one commits this fallacy if one argues that some action is morally impermissible because the law of the land or some other generally accepted code of conduct forbids the action, or that an action is morally permissible because the law or some code of conduct does not forbid it.
    There are two main reasons why this form of reasoning is fallacious.  First, the law does not forbid all actions that can on reasonable grounds be regarded as ethically impermissible.  There are good reasons for this: legislating morality is not consistent with the values of a free and open society.  If in every case of moral wrongdoing the government stepped in to prosecute the wrongdoer, we would find that the most personal aspects of our lives and personal relationships would be subject to the government's oversight--a way of life that would be demeaning to personal freedom and dignity.  Another good reason for not legislating morality is simply the impracticality of enforcing such broad legal proscriptions: there is simply too much immorality in society for any judicial system of reasonable size to handle.  Accepted codes of conduct adopted by clubs, professional organizations, etc., do typically make stricter demands of individuals than does the law, but even these codes of conduct can fail to proscribe actions that are immoral.  Thus an action that is allowed under the law or a particular code of conduct can still be immoral.
    A second, and more significant, reason that moral legalism is fallacious is that it simply does not follow from the fact that a legislative body within a state or a social group decides that some action should be proscribed that therefore the action is morally impermissible; nor does it follow from the fact that such a body does not proscribe an action that the action is morally permissible.  Historically it is not difficult to find examples of actions that can reasonably be considered to be morally permissible that were in fact illegal in their day.  To take one quite obvious example from the history of our country, the founding of the United States as a separate nation from England was an illegal act.  Thomas Jefferson, in the Declaration of Independence, offers a moral justification for the action, despite its illegality.  A perusal of historical and present day legal systems will also yield abundant examples of the legal acceptance of actions that are on any reasonable standards clearly immoral, from slavery to mass extermination of cultural and religious groups.
    None of this implies, of course, that we have moral license to do anything we want to do, legal or not.  There are very good moral justifications that one can offer in support of abiding by the laws of the state or the ethical codes adopted by other social groups.  But in moral discussion and debate, it is not enough to cite a law or an ethical code in support of a moral judgment--ethical principles and standards must be offered in support of adopting a law or ethical code as a reasonable normative standard.

Examples of moral legalism:

Moral Prudentialism

Prudence is a normative standard of action that requires rational agents to act in their own best interests.  Although it is certainly wise to follow the demands of prudence, and we do this every day when we brush our teeth, take medicine for an illness, and perform other actions that we believe will be a benefit to us, a fallacy is nevertheless committed when it is argued that a certain action or practice is morally permissible or required because it will benefit (is prudent for) one person or a certain group of people.  Thus if someone were to suggest that each person has a moral responsibility never to help others when doing so detracts from their own interests, the fallacy of moral prudentialism is committed.
    We will be considering in class an ethical theory known as "ethical egoism" which does not recognize moral prudentialism as a fallacy--in fact this theory says explicitly that the demands of prudence are in fact moral obligations, and thus we as moral agents are obligated to seek our own interests in all circumstances.  Although this theory has been accepted by some ethicists, it is generally rejected on the grounds that it leads to absurd conclusions.  We will consider these objections in class.

Other examples of moral prudentialism:

Slippery Slope Argument

A familiar tactic in ethical debate is to suggest that some practice should not be allowed because it will lead to dire consequences for society.  If sex education is allowed in the schools, the result will be rampant sexual promiscuity; if women are allowed equal status in the workplace to men, countless numbers of men will be jobless; if physician-assisted suicide is allowed, we will end up executing the physically disabled ("just as the Nazis did!").  The general strategy here is to suggest that even if a certain practice of itself is not morally objectionable, accepting it as morally permissible will lead us inevitably to consequences that are morally objectionable, and therefore the practice itself should be proscribed on moral grounds.  The problem with this strategy of argument is that it fails to establish that the foreseen, undesirable consequences will be inevitable.  Considering the examples used above, there is no reason to believe that the availability of sex education in schools leads to sexual promiscuity, that equal status for women in the work place will lead to widespread unemployment amongst men, or that allowing physician assisted suicide will inevitably lead to executing disabled people.  Without strong empirical evidence (which is typically not offered by people who use slippery slope arguments) the conclusion simply has no support.

Other examples of slippery slope arguments:

Argument to the People (also known in its Latin form, argumentum ad populum)

An argument to the people in support of a particular moral judgment involves an appeal to certain popular prejudices and biases shared by a large number of people.  Unlike moral conventionalism, which appeals to common practices, an ad populum argument is designed to inflame the passions of a certain audience, passions that will lead that audience to accept a certain moral conclusion.  For example, consider a hypothetical example of a conservative religious leader proclaiming the following to his equally conservative congregation:
No one who is in the faith, and true to that faith, can accept the scourge of abortion perpetrated by the godless heathens that are destroying our society.
The reference to "godless heathens" and their acts of  "destroying our society" will no doubt encourage many people to consider accept the implied conclusion of this argument, that abortion is morally wrong, but even if those who advocate the right of abortion in our society were primarily atheists (which in fact is clearly wrong from recent surveys), and even if these atheists were doing things that may be thought to be destroying the fabric of society, these facts would not establish by valid moral reasoning that abortion is morally wrong.  In fact, these facts are quite irrelevant to the question of the moral status of abortion.  This example suggests generally why ad populum arguments are fallacious: the prejudices and biases appealed to in such arguments, and the emotions they incite, are simply irrelevant to the moral issues they address.

Other examples of arguments to the people (ad populum arguments):

Red Herrings (sometimes known as the fallacy of "Irrelevant Premise" or in its Latin form "Non Sequitur," which means "it does not follow")

Red herrings are issues or points raised which are irrelevant to the conclusion that is drawn from these points or issues.  The strategy of this argument is to divert the attention of the person hearing the argument from real issues, ones that need to be addressed in order to evaluate the truth or falsity of a conclusion, to bogus issues, but in such a way that it is not clear to the hearer that the cited issues are bogus.  Consider a moral argument offered against the view that nonhuman animals are objects of moral concern (that is, that some forms of treatment of nonhuman animals are morally impermissible):
It doesn't matter what we do to animals, people are what matter.  Human beings have moral rights--you cannot morally do harm to any human being.  Animals are not people--they have no rights.
All that this argument says in support of the claim that it doesn't matter, on moral grounds, what we do to animals is the undeniable fact that human beings have moral rights.  But this fact is quite irrelevant to the question of whether nonhuman animals should be regarded as objects of moral concern.  From the fact that human beings are objects of moral concern, it does not follow that no nonhumans are objects of moral concern.  The issue of the moral status or human beings raised in the context of this argument is, therefore, a red herring.

Other examples of red herrings or non sequitur moral arguments:


1. Joan C. Callahan, ed., Ethical Issues in Professional Life (New York: Oxford University Press, 1988), p. 14. Back to Text

2. John Stuart Mill, On Liberty, ed. Alburey Castell (Arlington Heights, IL: AHM Publishing, 1947), p. 55. Back to Text


Next Chapter


Normative and Descriptive Statements

Normative and Descriptive Statements Quiz

Analyzing Simple Moral Arguments

Recognizing Fallacies in Moral Reasoning

Recognizing Fallacies in Moral Reasoning Quiz

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