Fallacy of Composition

In this fallacy, because a thing is composed of constituent parts some or all of which have some trait, then that trait is assumed to exist in the whole as well.

Similarly:

• Event X consists of sub-events A through N some of which have a characteristic.
• Therefore the entire event X has that characteristic.

The reverse of this fallacy is Division.

Examples

The team is composed of super-achieving people, therefore the team will achieve much as well. (Yet experience shows that the collective IQ of a team is almost always less than that of its individuals.)

The party that lasted from 6pm to midnight was a total disaster, because in the backroom at 8:23pm a cake fell own the floor and was ruined. If a part was ruined the entire thing is ruined.

Chuck is composed of slimy, wet organs like his liver and intestines, therefore Chuck is wet and slimy as a whole.

Weaknesses

It does not logically follow that because a thing has parts with various properties that the whole has those exact properties too.

You can point out that interactions of those parts determine the traits of the whole or collective.

Valid uses

The whole does inherit spatial characteristics. For instance, all of Chuck's organs are in the kitchen, therefore Chuck is in the kitchen.