Intermission

At a glance

Relevant Scripture

“Come now, and let us reason together, saith the LORD: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool.”

Isaiah 1:18 KJV

UECF.NET summary

Between the book's two halves, Keller steps back to explain the kind of reasoning Part Two will use. Everyone reasons about God from within what he calls a "plausibility structure" — an inherited web of background beliefs, experiences, and community that makes some conclusions feel obviously right before any single argument is even weighed. No one, skeptic or believer, approaches the God question from a neutral, view-from-nowhere vantage point; recognizing this is not an excuse to stop reasoning, but a reason to reason more honestly about our own starting assumptions.

Given that, Keller commits Part Two to a cumulative-case method rather than a single deductive proof: like a detective assembling clues that, individually, might each admit another explanation, but that together point strongly toward one conclusion; or like a jury asked not for mathematical certainty but for a verdict beyond reasonable doubt based on a preponderance of evidence. No one clue in the chapters that follow — the fine-tuning of the universe, the persistence of moral conviction, the historical case for the resurrection — is offered as an irrefutable, stand-alone proof. Keller's claim is that taken together, and weighed fairly, they add up to a reasonable, well-evidenced faith rather than a blind leap.

Main themes

• No one reasons about God from a neutral, assumption-free starting point.
• A cumulative case, weighing many clues together, fits the nature of the God question better than a single deductive proof.
• Being aware of one's own plausibility structure is the beginning of more honest reasoning, not the end of reasoning altogether.

Key ideas

• "Plausibility structure" names the background assumptions that make some ideas feel self-evidently true or false before argument even starts.
• A detective's method — assembling many clues into a coherent, best explanation — models Part Two's approach better than a mathematical proof would.
• Legal reasoning's "preponderance of the evidence" standard, not absolute certainty, is the appropriate bar for reasonable belief about God.
• This shift in method — from answering doubts to building a case — marks the hinge of the whole book.

Important concepts

• Cumulative case argument — An argument built from multiple independent lines of evidence that, together, support a conclusion more strongly than any one of them could alone.
• Plausibility structure — The background framework of assumptions, shaped by culture and community, that makes certain beliefs feel obviously credible or obviously absurd.
• Critical rationalism — Reasoning that seeks the most reasonable, best-supported conclusion available, rather than requiring proof beyond all conceivable doubt.

Related Bible references

• Isaiah 1:18
• 1 Peter 3:15
• Acts 17:2-3
• Romans 1:20

Practical Christian application

• Name one assumption in your own "plausibility structure" — inherited from family, culture, or experience — that shapes how open or closed you are to the God question before any argument is heard.
• Practice weighing a claim by cumulative evidence rather than demanding a single knock-down proof, the way a jury or a detective would.
• Ask God for honesty about which of your doubts, or convictions, you have never actually examined.

Questions for study