Also Known as: Fallacy of Lost Contrast, Fallacy of the Suppressed Relative
This fallacy occurs when a correlative (one of two mutually exclusive options) is redefined, in an unprincipled way, to include the other (thus eliminating it).
The fallacy has the following general form:
Premise 1: X and Y are correlatives.
Premise 2: X is (re)defined, without adequate justification, so that it includes Y.
Conclusion: There is no distinct Y.
This is fallacious because no adequate justification is given for accepting that Y must fall under the definition of X. A common example of this occurs in the debate over whether people are always selfish or occasionally altruistic. The usual error is to simply define “selfishness” so broadly that it eliminates all possibility of altruism. To illustrate, someone might define “selfishness” in terms of doing something because you think it is in your interest and then claim that there is no altruism, because any rational action is done in what a being thinks is its interest. As with any fallacy, the conclusion might be true; but it is not supported by the argument given. In this example, it cannot simply be assumed that this (probably question begging) definition is correct. This fallacy will often rest on definitions that are too broad (includes too much). For a discussion of the basics of good definitions, see the Straw Man: Balloon Man fallacy.
This fallacy could also occur when the (re)definition of X does not eliminate Y, but expands X in an unprincipled way to include what would otherwise be a Y.
This fallacy can be committed in ignorance when the person doing so does not realize that they have failed to provide adequate support for their (re)definition. It can also be committed intentionally in bad faith. For example, someone might use this fallacy to intentionally commit this fallacy to argue that there is only selfish behavior to rationalize their own selfishness.
Defense: The defense against this fallacy is to not accept a (re)definition of a correlative without considering the justification being offered for this (re)definition. It should also be kept in mind that attempting to (re)define a correlative need not be fallacious; it is the unjustified (re)definition that is fallacious.
Scrooge: “I believe that everyone is greedy. There is no generosity.”
Donald: “But people are often generous, even with strangers. People have helped me out a lot, even strangers who had nothing to gain.”
Scrooge: “Oh, they all got something. A person is greedy when they get something from doing something.”
Donald: “So what did they get? Like what did the person who gave me $10 when I was short of money when I was buying my insulin?”
Scrooge: “They got to feel superior to you and show off in front of other people. ‘Oh, look at me! Look at how generous I am!’”
Donald: “Well, what about those anonymous donations I got when I had to do a fundraiser to afford medical treatment? They didn’t get any attention for that.”
Scrooge: “Heck, they got something better than attention: the smug feeling of thinking they did a good thing without any credit. They are greedy for that feeling.”
Oscar: “Nature creates art.”
Immanuel: “Well, I suppose that could be true metaphorically.”
Oscar: “No, I mean literally. Art includes all that causes feelings in feeling beings! And nature does that. Think of a sunset! Think of the sea!”
Immanuel: “Think of bee stings and earthquakes.”
Immanuel: “I don’t think those would be art.”
Oscar: “Nonsense! The sting of a bee creates feelings! An earthquake creates many feelings!”