• Appeal to Consequences of a Belief
  • Argumentum ad Consequentiam

    Translation: Argument to the consequences (Latin)

Type: Red Herring
(Belief in) p leads to good consequences.
(Where the good consequences are irrelevant to the truth of p.)
Therefore, p is true.
(Belief in) p leads to bad consequences.
(Where the bad consequences are irrelevant to the falsity of p.)
Therefore, p is false.


…I want to list seventeen summary statements which, if true, provide abundant reason why the reader should reject evolution and accept special creation as his basic world-view. …

13. Belief in special creation has a salutary influence on mankind, since it encourages responsible obedience to the Creator and considerate recognition of those who were created by Him. …

16. Belief in evolution and animal kinship leads normally to selfishness, aggressiveness, and fighting between groups, as well as animalistic attitudes and behaviour by individuals.

Source: Henry M. Morris, The Remarkable Birth of Planet Earth (Creation-Life Publishers, 1972), pp. vi-viii.



Arguing that a proposition is true because belief in it has good consequences, or that it is false because belief in it has bad consequences is often an irrelevancy. For instance, a child's belief in Santa Claus may have good consequences in making the child happy and well-behaved, but these facts have nothing to do with whether there really is a Santa Claus.

Beliefs have many consequences, both good and bad. For instance, belief that smoking cigarettes causes lung cancer may have such bad consequences as frightening cigarette smokers or making them depressed, but it may also have such good consequences as motivating people to stop smoking, thus lowering their risk of cancer. However, the most important consequences of the belief, or lack thereof, that smoking causes lung cancer are affected by the fact that it does so. In other words, we cannot determine the truth-value of a belief from its consequences alone, since many of those consequences are dependent upon its truth-value. If smoking didn't cause disease, then the bad consequences of believing it does would greatly outweigh the benefits; but since it does, the situation is reversed.

Since the irrelevancy of belief to truth-value is intuitively obvious, it is often suppressed in fallacious Arguments to the Consequences. However, one can tell that the fallacy is being committed because the supposed consequences do not follow from the proposition itself, but only from belief in it.


There are two types of cogent argument with which this fallacy is easily confused:

  1. When an argument concerns a policy or plan of action—instead of a proposition—then it is reasonable to consider the consequences of acting on it.
  2. When an argument is about a proposition, it is reasonable to assess the truth-value of any logical consequences of it. Logical consequences should not be confused with causal consequences, and truth or falsity should not be confused with goodness or badness.

Appeals to Consequences differ from these cogent forms of argument in the following ways:

  1. The argument is not about a plan or policy, but a proposition which therefore has a truth-value.
  2. The argument does not concern the truth-value of logical consequences of the proposition, but the good or bad causal consequences of believing it.



David Hackett Fischer, Historians' Fallacies: Toward a Logic of Historical Thought (Harper & Row, 1970), pp. 300-302.


Dr. Michael C. Labossiere, "Appeal to Consequences of a Belief"

Analysis of the Example:

Two of the seventeen reasons that Morris gives for belief in creationism are appeals to consequences: 13 is an appeal to the supposed good consequences—"salutary influence"—of believing in creationism, and 16 is an appeal to the supposedly bad consequences of belief in evolution. One may doubt whether these are really consequences of these beliefs, but even if so they are irrelevant to the truth or falsity of creationism and evolution. Even if belief in creationism makes people polite and well-behaved, it may be false for all that; even if belief in evolution tends to make people selfish and aggressive, it may be true for all that. Belief in Santa Claus may make people less selfish and aggressive, but sorry, Virginia, there is no Santa Claus.

Reader Response:

I do not see how the quoted text is an example of the fallacy according to both your exposition and analysis. In your exposition you state, "Arguing that a proposition is true because belief in it has good consequences, or that it is false because belief in it has bad consequences is often an irrelevancy." And in your analysis you state, "One may doubt whether these are really consequences of these beliefs, but even if so they are irrelevant to the truth or falsity of creationism and evolution." So it would seem that to fall into "appeal to consequences" one must argue for the truth or falsity of the proposition based on its consequences. But looking back at the quote, I could not find an argument for the truth or falsity of the worldview, only a statement as to why people should accept it. To accept a worldview is to believe it. Moreover, Morris is arguing that "belief" in creationism has good effects and "belief" in evolution has bad effects, therefore you should believe in creationism. You wouldn't get the supposed good effects if you didn't believe it, at least according to Morris. To put it in terms of your Santa Claus example, it would read:

Premise: Kids who believe in Santa are well behaved.
Premise: Kids who don't believe in Santa are poorly behaved.
Therefore, we should teach kids there is a Santa.

At no point did the example argue that there really is a Santa. If the premises are false, then the argument cannot be sound, but the validity of the argument is independent of the truth or falsity of the premises. The counter-example may break down for the author's point of view, since I do not know any adults who believe in Santa. A more applicable example may be:

Premise: Belief in a Deity leads to the following good results.
Premise: Rejection of a Deity leads to the following bad results.
Therefore, you should believe in a deity.

Again, it does not argue for the truth of the belief. I recognize that Morris was a creationist and certainly thought the proposition to be true, I just don't see the quoted text arguing for that truth at all.―Colin

Generally, if someone argues that you should believe something, that's equivalent to arguing that it's true. Of course, there's a subtle distinction between arguing that something is true and that you should believe it, and Morris could have written something like: "The following reasons have no bearing on the truth or falsity of creationism or evolution, but are reasons why you should believe the first and not the second". However, he did not. Instead, he simply included his appeals to consequences among a long list of other reasons. For instance, the reason immediately preceding the first appeal to consequences is the following:

12. There are more natural phenomena indicating the earth is very young than those indicating it is old, and all the latter can easily be reinterpreted in terms of young age.

This is a reason to believe in creationism as opposed to evolution, but only in the sense that it is a reason to think that the former is true and the latter false. Just because Morris doesn't explicitly say that he is arguing for the "truth" of creationism doesn't get him off the hook, since that is what arguing for "acceptance of" or "belief in" a theory ordinarily amounts to.