 But in R, this harmless appearance is deceptive. For in this logic the connective ↔ is what we have called special. After the well-known extension, R-Mingle or RM, of R by the Mingle schema φ → (φ →  φ),[48]  let us call a formula φ for which this is already provable in R a Mingler. Since RM is a proper extension of R, not all formulas are Minglers in R. But again thanks to contraction, all ↔-formulas are Minglers, rendering ↔ special in R. Now we can see that the addition of T, subject to the schema inset above, would extend R non-conservatively because now every formula φ would be equivalent to the corresponding ↔-formula T ↔ φ, so even for T-free φ we should have the Mingle theorem φ → (φ → φ). Thus no devotee of R should be prepared to countenance the existence of T behaving as envisaged (or indeed any pair #1, #2 of 1-ary connectives with φ provably equivalent to #1φ ↔ #2φ).