Peirce once claimed seriousness in irony. He practiced other forms of literary indirection as well. And he explored conjectures without being committed to any one formulation of them. To take everything he said seriously is to miss what he was serious about. This applies most to his two most famous essays, ‘The Fixation of Belief’ and ‘How to Make Our Ideas Clear’. The first is ironic in structure and purpose. The second poses a multitude of interpretative problems of which some, evidently intended, point us toward an irony, not of literary style but in a basic thrust of Peirce’s thought, opposing modern science to modernity.