  In his earliest paper, Landauer derived the cost of performing the reset operation by simply assuming that there is an equivalence between the Shannon information of a distribution of logical states, and thermodynamic entropy of a physical system that can represent those logical states. A reduction in the Shannon information content of the logical states would then reduce the thermodynamic entropy of the physical system. Landauer then further assumed that the second law holds true and that this reduction must produce a thermodynamic entropy increase elsewhere. Viewed in this way, his argument appears to contain elements both of the profound and the sound horns of Earman and Norton's (1998, 1999) dilemma. It follows the profound horn in identifying Shannon information with thermodynamic entropy and the sound horn in assuming the validity of the second law.