Hello, I’m Pang Ying. Welcome to Episode 6 of Think Like a Debater.

At the start of I Can I BB Season Six, Zhan Qingyun faced a formidable engineering doctoral student educated in France on whether to resurrect a deceased partner. He opened: as a science student, this is an easy question; let me prove it with a classic syllogism.

Major premise: Being alive is good.

Minor premise: My partner is a person.

Conclusion: Resurrecting my partner is good.

The audience cheered: “So logical!”

Today we ask what a syllogism is, whether it can be rebutted, and how.

A syllogism is a crucial logical form with three parts: major premise, minor premise, and conclusion. For example:

Major premise: All humans are mammals.

Minor premise: All debaters are humans.

Conclusion: All debaters are mammals.

It sounds odd, but it is correct: we are mammals.

A syllogism depends on inclusion, or conversely subordination.

“All humans are mammals” means humans are entirely included within the larger class of mammals. If mammals are a room, humans are a box inside it.

“All debaters are humans” means debaters are a smaller box inside the human box. Because the box is in the room, the smaller box must also be in the room; therefore all debaters are mammals.

A syllogism is a valid logical structure. Insert true premises in a valid form and its conclusion is necessarily true; you need not separately inspect the conclusion’s content.

A syllogism is therefore a form ofdeductive argument: if its premises are true, its conclusion cannot be false.

Deduction derives particular conclusions from general principles.

Knowing all humans are mammals and all debaters are humans tells us every individual debater is a mammal: Pang Ying, Zhan Qingyun, and Huang Zhizhong alike. This moves from general to particular.

By contrast, there isinductive argument.Induction moves from particulars to a generalization. If we did not know humans were mammals, we might examine East Asians and Africans, then ask whether an unusual human group hidden deep in a forest lacked mammalian traits.

Induction is not 100% reliable because its premises contain less information than its conclusion, leaving some risk of error.