The Case Of The Unexpected Sermon: Discovering The Value (and Dangers) Of Abductive Preaching
By Robert B. Stewart
People reason in one of three general ways: deductively, inductively, or abductively. Assuming that one's argument is valid in form and each individual premise is true, the conclusions of deduction are logically certain. Induction and abduction yield no such logical certainty. Induction is based upon observation of repeated experience, and thus leads one to a probable conclusion. Abductive reasoning offers one neither a certain nor probable conclusion. It does, however, attempt to offer an explanation of the facts, why things are the way they are. In other words abduction seeks to determine the most plausible solution to a problem.
Abduction is a type of pragmatic reasoning, given its formal name by the American philosopher Charles Sanders Peirce (1839-1914).1 Peirce did not invent abduction; human beings have always practiced it. He did, however, give formal expression to something that people have always done, thus allowing future reasoning of this sort to be done in a more critically aware and consistent manner. Abduction is a hybrid form of reasoning, sharing certain characteristics with both induction and deduction, while remaining neither. Like induction abduction makes us of a posteriori observation to reach its conclusion, a conclusion not guaranteed to be true. Unlike induction it is not simply about the probability of such and such being the case based upon repeated or prior observation. Like deduction abduction begins with an a priori hypothesis (rule) and reasons to an application of that rule in particular. Despite the fact that neither induction nor abduction renders a conclusion certain,2 both are nevertheless important forms of reasoning.
Advertisement
The logical order differs in the three different types of reasoning. Deduction works from rule to case to result; induction, from case to result to rule; and abduction, from rule to result to case. The differences in logical order are illustrated below:
Deduction
Rule All A are B Rule All the beans from this bag are white Case C is A Case These beans are from this bag Result Therefore C is B Result Therefore these beans are white
Induction
Case C is A Case These beans are from this bag Result C is B Result These beans are white Rule Therefore all A are B Rule All the beans from this bag are white
Abduction
Rule All A are B Rule All the beans from this bag are white Result C is B Result These beans are white Case Therefore C is A Case Therefore these beans are from this bag
But perhaps an example from Sir Arthur Conan Doyle would be more helpful (and enjoyable).
The portly client puffed out his chest with an appearance of some little pride and pulled a dirty and wrinkled newspaper from the inside pocket of his greatcoat. As he glanced down the advertisement column with his head thrust forward and the paper flattened out upon his knee, I took a good look at the man and endeavored, after the fashion of my companion, to read the indications which might be presented by his dress or appearance.