Tag Archives: illicit conversion

Some beaches are illicit conversions

OK, so I’ve been watching football.  And there are occasions to think about logic.  During the beer commercials.  First, though, a quick tutorial on deductive semantic fallacies.  An argument is fallacious on deductive semantic grounds when the truth of the argument’s premise does not guarantee the truth of the argument’s conclusion (provided the proper analysis of the terms of the logic). A classic fallacious move to make inferences between two forms of statements in categorical A-Form.

All S are P, so All P are S

The pattern is conversion – you switch the subject and predicate term in the proposition form.  It’s valid for E- and I-Forms, so it’s fine for these:

No S are P, so No P are S

No cats are lizards, so No lizards are cats

Some S are P, so Some P are S

Some Texans are Republicans, so Some Republicans are Texans

The trouble is that with A-form propositions, conversion is fallacious.  So we can intuitively see the fallacy with the following conversion forms:

All triangles are polygons, so All polygons are triangles

All cats are mammals, so All mammals are cats

That’s fallacious, and since it’s a bad way to convert, we call it illicit conversion.  Now, to the commercials.  See the following Corona commercial, effectively playing during every timeout for every NFL game this weekend.  HERE.  Here’s the free association that stands in for reasoning:

Some beaches have sand; Some beaches are backyards; Some beaches inspire ideas; Some beaches have beats; Some beaches are better after sunset; Every beach is different, but All beaches have Corona

The commercial has scenes of beaches, bars, mixing rooms, back yards, concerts, campgrounds and so on. Each is some poignant scene, but not all have beers in them.  The inductive evidence presented is that, given their special definition of beach (effectively meaning ‘special place’), it’s not the presence of Corona that makes them that.  Rather, it, at best, is that the presence of Corona can contribute to a place being a beach.  Consequently, it isn’t that All beaches have Corona that they’ve shown.  It only takes the first scene (the sandy beach with no beers) to be a counter-example.  Instead, the best that the evidence could show is that All places where there are Coronas are beaches in the relevant sense.  Trouble is, they conclude with All beaches have Corona.  Illicit conversion off weak evidence for enumerative induction.