David Miller is the foremost exponent of the purist critical rationalist doctrine and here presents his mature views, discussing the role that logic and argument play in the growth of knowledge, criticizing the common understanding of argument as an instrument of justification, persuasion or discovery and instead advocating the critical rationalist view that only criticism matters. Miller patiently and thoroughly undoes the damage done by those writers who attack critical rationalism by invoking the sterile mythology of induction and justification that it seeks to sweep away. In addition his new material on the debate on verisimilitude is essential reading for all working in this field.