The two-dimensional Ising model is mapped to itself by a high-low temperature duality. The image of the spin operator σ σ under this duality is a disorder operator μ μ , which has the same left and right conformal dimensions ( Δ Δ μ μ , Δ Δ ¯ ¯ μ μ ) = ( Δ Δ σ σ , Δ Δ ¯ ¯ σ σ ) = ( 1 16 , 1 16 ) . Although the disorder operator does not belong to the minimal model, correlation functions involving the disorder operator can be computed exactly, for example