Fallacies

Systems of classification

Fallacies are generally classified strictly by either their structure or their content, such as by classifying them as formal fallacies or informal fallacies, respectively. The classification of informal fallacies may be subdivided into categories such as linguistic, relevance through omission, relevance through intrusion, and relevance through presumption. Alternatively, fallacies may be classified by the process by which they occur, such as material fallacies (content), verbal fallacies (linguistic), and formal fallacies (error in inference). In turn, material fallacies may be placed into the more general category of informal fallacies. Verbal fallacies may be placed in either formal or informal classifications: Compare equivocation, which is a word- or phrase-based ambiguity, to the fallacy of composition, which is premise- and inference-based ambiguity.