If we rely on experiences as evidence for our inferences and explanations, we must screen the ways in which we handle those that offer themselves so as to avoid making unwarranted presumptions about them and to avoid exploiting their ambiguity in various tempting ways. Otherwise, we may be guilty of fallacies of presumption and ambiguity in a variety of ways. Examining them will help us avoid egregious errors in our thinking. Although thinking that commits such fallacies is common, it is always misleading.
If we rely on experiences (or anything else for that matter) as evidence for our inferences and explanations, we must screen the ways in which we handle them in order to avoid making unwarranted presumptions about them and equivocating over what they mean.
A. These cautions are also prerequisites for useful inference drawing.
B. When we presume, in one way or another, facts that are not in evidence, and when we play fast and loose with the meanings of our locutions, we are (once again) “not even in the ballpark, much less in the game.”
Here are descriptions and examples of eight forms that such bad reasoning can take.
A. Petitio principii
This fallacy amounts to inferring a conclusion from premises that are, in fact, indistinguishable from the conclusion itself. This fallacy is also called circular reasoning and question begging. Example: I know that God exists because the Bible says so. And I know that everything in the Bible is true because it is God’s word and God wouldn’t lie.
B. Complex question
This fallacy amounts to presuming without evidence that a certain state of affairs obtains, then shaping one’s inquiry in terms of that presumption. Example: The classic is “Have you stopped beating your wife?” but it is equally clear in “Don’t you want to be a good boy and go to bed?”
This amounts to exploiting ambiguities of words. Some are simple plays on an everyday noun or adjective. Some exploit the subtleties of dispositional and episodic participles. Examples: When mother asks, “Were you good at the party, Susie?” Susie responds, “Well, Miles said I was.” When father asks, “Are you smoking [these days], Fred?” Fred responds, “No I’m not [right this moment].”
This fallacy amounts to exploiting ambiguities of syntax. Example: A subway rider explains why he lit a cigar right next to the sign that said “No Smoking Allowed” by noting the two ways that sign can be read: “Smoking is forbidden” and “Refraining from smoking is permitted.”
This fallacy amounts to exploiting ambiguities of emphasis, including selective data use. Example: Story positioning in the media, headline writing, and small print on a box of Broccoli Rice Surprise show just what accent can do.
F. Category mistake
This fallacy amounts to exploiting ambiguities of classification. The term comes from Gilbert Ryle’s The Concept of Mind. Example: Not seeing the forest for all the trees, the parade for all the marchers, and the university for all the buildings and greens are all examples of confusing things and systems. “If we have minds, then where are they?” is a more telling case in point.
G. Composition and division
These fallacies amount to exploiting ambiguities between the properties of individuals and the properties of the sets that they compose. Example: “Everyone in my gymnastics class is tiny. There’s no one there over 80 pounds. I can’t see why the instructor is complaining that the class is too big.”
H. False dilemma
This fallacy amounts to exploiting ambiguities of complementarity. Example: “Well, Ali was certainly no hero, so he must have been a coward.”