The Three Reasoning Methods: Deductive, Inductive & (by far the most common) Transductive

by Robert Archerd

Come election time, some of us should hone our reasoning skills. The two go-to methods of (sound) logical reasoning are deductive (general to specific) and inductive (specific to general), in which either can lead to a valid conclusion. And to this end no other reasoning method is considered effective.

The deductive approach, though it’s known as the general-to-specific method, this description can be misleading. For example, nothing can be more specific than, “All whales are mammals. Herbie is a blue whale, and is therefore a mammal.” See how declaring that general-to-specific can mislead? At any rate, the deductive approach (deduction) generally begins from notions expressed as premises, then moves forward in steps to a specific conclusion. It fits well into the if-then-therefore framework, and is often called the top-down approach.

The deductive method is said to yield results that are certain, which is not necessarily so with induction. That’s also misleading, since the results from deduction depend entirely on the veracity of its premises; if the premises of a deductive presentation are perfectly solid, the conclusion is not up for debate. But you can see, then, that the deductive method has its own built-in redundancy — and we know our answer needs no other test than a cursory examination of its premises. So, since the result is a given, isn’t this simply circular reasoning…