Chapter 6: Non-Emptiness and Strictness

The Canonical Ladder Theorem asserts three properties of the enrichment tower E₀ ⊂ E₁ ⊂ E₂ ⊂ E₃: each layer is non-empty, each inclusion is strict, and the tower saturates at E₃. This chapter earns the first two pillars. Non-emptiness requires constructive witnesses at each layer. Strictness requires obstruction arguments proving that structures at layer E_k cannot be reduced to layer E_k-1. Saturation is deferred to the relevant chapter.