During the discussion portion of last Sunday’s class I referred to the process of working though the details (or particulars) of a biblical text and arriving at truth from them. For example, we work through an epistle (or letter) and try to figure out what might have occasioned that writing. This is often referred to as the “Inductive Method” of Bible study, where we identify clues and work to find the generalizations that they flow from. I threw in that Sherlock Holmes worked this way. Then, we got a little twisted around about what is induction, what is deduction, and what roles they play in our study of the Bible (or detective work).

I think part of the confusion is that the inductive method is actually properly classified as abduction. Abduction is a process of inference to the best explanation, which is really an iteration between induction and deduction. 

 The following quote from a page I found on crime-scene investigation says it well…

While most people have heard of deductive and inductive reasoning, more important to detective work is an approach called abduction.  According to Nordby, there are important distinctions to be made:

• Induction is statistical reasoning toward a probable conclusion based on the frequency of certain things occurring.  (All of John Wayne Gacy’s victims found to date were male, so Gacy did not kill females.)
• Deduction is a specific conclusion restricted by the actual evidence or claims made in a chain of reasoning that leads up to it. (All of Lucas’s confessions are dubious.  Lucas confessed to killing “Orange Socks.”  So Long’s confession about “Orange Socks” is dubious.)  It draws out something that’s already contained in the claims. 
• Abduction is the process of proposing a likely explanation for an event that must then be tested.  (We think that Christine Schultz’s killer may have had a key to her home.)

A little more formally from Wikipedia…

Deduction 

allows deriving b as a consequence of a. In other words, deduction is the process of deriving the consequences of what is assumed. Given the truth of the assumptions, a valid deduction guarantees the truth of the conclusion.

Induction 

allows inferring some b from multiple instantiations of a when b entails a. Induction is the process of inferring probable antecedents as a result of observing multiple consequents.

Abduction 

allows inferring a as an explanation of b. Because of this, abduction allows the precondition a of “a entails b” to be inferred from the consequence b. Deduction and abduction thus differ in the direction in which a rule like “a entails b” is used for inference. As such abduction is formally equivalent to the logical fallacy affirming the consequent.

It is important to note that abductive arguments are technically a logical fallacy. This doesn’t mean that they are not true, only that they do not form necessary proofs. The best example I’ve heard on this comes from Ron Nash… 

• Litmus paper turns red when dropped in acid (blue when dropped in a base).
• The litmus paper turned red when dropped in a solution.
• The solution must be acidic. 

Hopefully you can see how this is logically invalid, while still remarkably useful. 

Only deductive arguments are properly logical, and the Bible doesn’t always give us the sweeping generalities that allow us to use simple deduction. Because so much of the Bible is narrative (telling stories) and letters (employing task theology) and the like, we have to work backward to the generalities. When we do this, we are always subject to the possibility of getting it wrong.

This is why we always want to approach the process with humility and deal with those with whom we disagree with Christian charity. This doesn’t mean we become jellyfish without conviction, but it does mean that we always maintain a position that we could be wrong and remain open to correction when shown a better way to understand and harmonize what we find in the Bible.

This is also why our systematics always have to be tested against the particulars we find in the Scriptures (i.e., testing our hypotheses against the revealed truth of Scripture). That is to say, nothing in our systematic theology may be allowed to contradict a clear passage of Scripture. If that happens, we are obligated to adjust our system. On the other hand, we do not let one obscure verse where the meaning is unclear nullify the understanding we have in passages that are clear. For example, we do not let a passage like 1 Cor. 15:29 unravel the clear understanding that we get elsewhere in the Bible on baptism.