Reasons to Believe

How to Evaluate an Abductive Argument

Logic gives us a checklist for our thoughts. It orders our thinking and prepares us to present our beliefs to others in a clear and consistent way. For Christians, this is an invaluable apologetics and evangelistic tool.

Three approaches in logic are deduction (establishes certainly true conclusions), induction (establishes probably true conclusions), and abduction (uses a set of established facts to infer to the best explanation). Though less well known, the abductive approach can powerfully and effectively argue that the biblical God provides the best explanation for the most meaningful realities of life. But how do we know we’ve arrived at the best explanation? Consider these six criteria for evaluating any abductive argument.

1. Is it coherent? An argument must be logically consistent, with no internal contradictions. An incoherent argument has to be false; a coherent argument may be true.

2. Does it correspond to the facts? A good explanation brings the facts together in such a way that they make sense. We can’t assume our own facts or distort the facts.

3. Does it balance complexity and simplicity? Occam’s razor states that among competing theories, the simplest one should prevail. But people make a mistake when they think Occam’s razor is just simplicity. A good theory still has to be able to explain all the data in the simplest way—thus, the need for balance.

4. Does it avoid unwarranted presumption? We all bring presumptions and biases to the table that must be examined and, perhaps, discarded.

5. Does it accommodate possible counter evidence? A good hypothesis is pliable and can accommodate challenging evidence without collapsing.

6. Does it possess genuine explanatory power and scope? A good hypothesis will explain things comprehensibly (power) and will explain all the really important things (scope). While Judaism and Islam explain a lot, I would argue that Christianity’s power and scope extends farther.

Subjects: Logic

Kenneth R. Samples

I believe deeply that “all truth is God’s truth.” As an RTB scholar I have a great passion to help people understand and see the truth and relevance of Christianity’s truth-claims. Read more about Kenneth Samples.