The last two fallacies of this unit move a property between a whole and its parts. Both trade on an ambiguity between saying something of each part and saying it of the whole.
Key idea
Composition reasons that because every part has a property, the whole must have it too.
Why it works
Some properties add up and some do not. If every brick is red, the wall is red. But if every brick is light, the wall is not light: weight adds up. Great players can make a poor team, because playing well together is not the sum of playing well alone.
Worked example: Does it add up?
"Every song on the album is short, so the album is short."
- Each part: a short song. The whole: the album.
- Length adds up: many short songs can make a long album.
Answer: Composition.
Worked example: It carries over
"Every piece of the puzzle is made of wood, so the puzzle is made of wood."
- What something is made of carries over from its parts.
- A whole made only of wooden pieces is wooden.
Answer: Not a fallacy.
Common mistake
Assuming every property fails to carry over. Some do (color, material: if every brick is red, the wall is red). Ask whether this particular property is one that adds up or changes when parts come together.