Arguments from Ignorance

accept accused ad ignorantiam argument Alger Hiss analysis appeal to ignorance appear argu arguer argument from ignorance argument scheme argumentation stage argumentum ad ignorantiam basis burden of proof Chapter characteristic cited claim closed world assumption commitment conclusion conditional premise context of dialogue critical discussion defined dialectical disprove Eemeren and Grootendorst evaluation example expert failure given goal of dialogue guilty Hamblin hominem igno ignorantiam argument ignorantiam fallacy inference informal fallacies inherently innocent inquiry issue kind of argument knowledge base knowledge-based lack of knowledge Lockean logue ment mentum ad ignorantiam modus tollens negation negative evidence negative proof nonfallacious participant party persuasion dialogue Pierre Berton Planet X plausible practical reasoning pragmatic presumed presumptive reasoning problem profile of dialogue proponent prove question rance rantiam relevant respondent rules sequence of argumentation shift the burden side speech act structure tactic thesis tion type of argument type of dialogue Walton