Study Guide: Chapter 1 — The Reach of Explanations

Core Idea

Knowledge comes from conjecture criticized, not from the senses. Good explanations are hard to vary — every detail load-bearing — and that property gives them reach: they solve problems far beyond the ones they were built for.

Key Terms

Good explanation · reach · hard-to-vary · empiricism (rejected) · theory-laden observation

Case Summary

Seasons: the Persephone myth explains nothing (any detail swappable; misses opposite hemispheres). Axial tilt is hard to vary, predicts opposite seasons, reaches to unseen planets.

Application Checklist

• [ ] Variability test one belief: could it explain the opposite outcome with a tweak?
• [ ] Prefer accounts where every component is load-bearing
• [ ] Prize principles that solve problems they weren't designed for

Self-Test

1. Why is "hard to vary" better than "fits the data"?
2. What is reach, and why isn't it a matter of choice?
3. How does explanation-first epistemology beat empiricism on unobservables?