Logic is concerned with the design or structure of arguments. It describes the forms of valid argument and is concerned with the public presentation and reception of arguments. Hence it has a close connection with politics and the public sphere, and with rhetoric as the science of persuasion. Philosophers have analysed the objective conditions of validation, that is, the justifiability of assertions about the world. This quest for objective and scientific validity in argumentation about the nature of reality dominated much of the development of logic in the 20th century. Logical arguments are held to be successful as a result of the ‘force of reason’ rather than because one’s opponents have been bribed or coerced. Logic involves the study o...