Every unexplained proposition is unexplainable by design or obligation.

Evidence

I wished to understand so that every unexplained proposition should appear to my reason necessarily unexplainable, and not an obligatory part of belief. — Leo Tolstoy, A Confession, 215

Categorization

• corroborated: 2 independent passages support this claim — Leo Tolstoy, A Confession, 215
• XREF: connects to: Unless you know it all, there will always be truths that are by their very nature unknowable. — What Are The Limits of Knowledge?; Certain philosophical problems like the mind–body problem may be fundamentally unknowable by humans due to cognitive closure. — Cognitive closure (philosophy)