F013 • Formal - Syllogistic Logic
Also known as: Illicit Process of the Minor Term
Knowing where a small group fits doesn't tell us about the boundaries of the larger group.
We learn that one group fits inside another and find ourselves flipping the relationship -- concluding that the larger group must fit inside the smaller one. The conclusion quietly reverses the direction of containment.
Loading examples...
Pattern: All A are B; all A are C; therefore all C are B.
Terms:
A = Known group (cats)B = First property (mammals)C = Second property (animals)Steps:
A have property BA belong to CC have property BWhen we learn that all cats are animals and all cats are mammals, the relationships feel symmetric. There is a pull toward concluding that all animals are mammals, as though the containment runs both ways. In everyday life, this kind of reversal often works: if everyone in the office likes coffee, and everyone in the office is on the third floor, it is tempting to think everyone on the third floor likes coffee. Sometimes that is even true -- but not because the reasoning is valid. The minor term, the subject of the conclusion, gets expanded from 'some' to 'all' without the premises warranting it. The premises told us about cats, but the conclusion claims to know about all animals. That expansion is where the seam splits.
| The instinct to generalize from a subset to a larger group serves us well most of the time. When the premises genuinely cover the full scope of the conclusion's subject, the reasoning is perfectly valid |
| Categorical reasoning becomes reliable here when the minor term is properly constrained in the premise -- meaning the premise really does address all members of the group the conclusion is about |
| Pay attention to the subject of the conclusion. Ask: did the premises actually tell me about all members of this group, or only about a subset? |
| You might catch yourself reversing a containment relationship -- feeling that because A fits inside B, B must fit inside A. That reversal is the hallmark of this pattern |
| Watch for conclusions where the subject term is broader than anything the premises discussed. If the premises talked about cats but the conclusion talks about all animals, something expanded |
| When a conclusion feels like it follows naturally, try explicitly checking: is the subject of my conclusion the same scope as what the premises addressed? |
| Difficulty seeing the asymmetry between the minor premise and the conclusion, especially when the conclusion sounds plausible on its own merits |
| Mixing up which term is the minor term (the subject of the conclusion) versus the major term, leading to misidentifying which expansion happened |
| Illicit Minor |
|---|
| The minor term is distributed in the conclusion but not distributed in the minor premise. |
| You cannot make a claim about all members of a category in the conclusion if you haven't made such a claim in the premises. |
Hover to see definition, click to view full details