Fallacy of division

The fallacy of division^[1] is an informal fallacy that occurs when one reasons that something that is true for a whole must also be true of all or some of its parts.

An example:

The second grade in Jefferson Elementary eats a lot of ice cream
Carlos is a second-grader in Jefferson Elementary
Therefore, Carlos eats a lot of ice cream

The converse of this fallacy is called fallacy of composition, which arises when one fallaciously attributes a property of some part of a thing to the thing as a whole.

If a system as a whole has some property that none of its constituents has (or perhaps, it has it but not as a result of some constituent's having that property), this is sometimes called an emergent property of the system.

The term mereological fallacy refers to approximately the same incorrect inference that properties of a whole are also properties of its parts.^[2]^[3]^[4]

^ "Division". Retrieved 2024-05-10.
^ M. R. Bennett; P. M. S. Hacker. 2003. Philosophical Foundations of Neuroscience. Table of contents.
^ Rom Harré. Behind the Mereological Fallacy. Philosophy 87:3, July 2012, pp. 329-352. https://doi.org/10.1017/S0031819112000241
^ P.M.S. Hacker. 2013. Before the Mereological Fallacy: A Rejoinder to Rom Harré. Philosophy, 88(1), 141-148. doi:10.1017/S003181911200054X

[Division-1] "Division". Retrieved 2024-05-10.

[2] M. R. Bennett; P. M. S. Hacker. 2003. Philosophical Foundations of Neuroscience. Table of contents.

[3] Rom Harré. Behind the Mereological Fallacy. Philosophy 87:3, July 2012, pp. 329-352. https://doi.org/10.1017/S0031819112000241

[4] P.M.S. Hacker. 2013. Before the Mereological Fallacy: A Rejoinder to Rom Harré. Philosophy, 88(1), 141-148. doi:10.1017/S003181911200054X

[1]

[2]

[3]

[4]