Methodological naturalism is the most justified inquiry principle available—but it is a principle, not a presupposition, and not a metaphysical claim. This chapter explains exactly what it says, what it doesn't say, why it works, and where it reaches its limits. The single most important distinction: methodological vs. metaphysical naturalism.

Not all foundations are equal. This chapter introduces the three-tier taxonomy at the heart of Foundations of Reason: axioms (what you cannot think without), presuppositions (what you cannot live without), and principles (what works well enough to earn its place). The grammar that structures everything that follows.

You have explored the universe. You have learned to think clearly. Now comes the question beneath both: What must you assume before you can think at all? This introduction lays the groundwork for the entire book—introducing the three-layer taxonomy of axioms, presuppositions, and principles, and showing why understanding your own foundations matters more than ever in an age of competing worldviews and synthetic intelligence.