Subject: Re: Induction

From: Nick Nicholas <[email-masked]>
Date: Mon, 27 Aug 2001 00:20:08 -0700

cu'u la xod.

> What is the difference between abduction and deduction?

Deduction: I have a Case, and a Rule, and I infer a Result

Case: Socrates is human
Rule: All humans are mortal
Result: Therefore, Socrates is mortal

Induction: I have a Case and a Result, and I infer a Rule

Case: Socrates is human
Result: Socrates is mortal
Rule: Therefore, All humans are mortal

(If you're a good scientist, you haven't used just one Case-Result pair!)

Abduction: I have a Result and a Rule, and I infer a Case

Rule: All humans are mortal
Result: Socrates is mortal
Case: Therefore, Socrates is human

As is well known, abduction is logically just silly (the classic
counterexample is, Socrates is a fruit fly.) But human are forced to do
abduction all the time. For instance, language parsing: you're working
backwards from the Result (the sentence you heard) and the Rule (grammar)
to obtain the Case (what was meant). Unlike deduction, abduction is indeed
logically fallible; that's why misunderstanding sentences is possible.

induction is sucta. deduction and abduction are both tolsucta. deduction is
the logical reverse of abduction.

Nick Nicholas, TLG, UCI, USA. [email-masked] www.opoudjis.net
"Most Byzantine historians felt they knew enough to use the optatives
correctly; some of them were right." --- Harry Turtledove.