ABSTRACT
Consider the sentence “Either the chemical is not iodide or its viscosity is 14.” What of the case when the chemical is iodide? To communicate this situation to someone, you might complete the rephrasing “If the chemical is iodide, then” with the consequent “its viscosity is 14.” Although these sentences use different connectives, they are logically equivalent. Despite this, the task of rephrasing between them is nontrivial Indeed, the author witnessed an experienced chemical engineer rephrase a similar example as “If the chemical is iodide, then its viscosity is not 14.” It was only some minutes later that the engineer realized that this rephrasing was incorrect, noticing that it did not coincide with his knowledge of the properties of iodide. He did so by rephrasing the rephrasing itself, stating “Hang on, so in that case, either the chemical is iodide or its viscosity is 14 which is clearly wrong.” Why he was unable to rephrase between disjunctive and conditional forms, and why he
chose this approach to testing the validity of his rephrasing, exemplify the research questions that are explored in this chapter.
