 In a 1912 pioneering article in Mind “Implication and the Algebra of Logic” C.I. Lewis started to voice his concerns on the so-called “paradoxes of material implication”. Lewis points out that in Russell and Whitehead’s Principia Mathematica we find two “startling theorems: (1) a false proposition implies any proposition, and (2) a true proposition is implied by any proposition” (1912: 522). In symbols: