Words and Rules: The Ingredients of Language is a 1999 popular linguistics book by Steven Pinker about regular and irregular verbs. "Words and rules" is a theory that has been predominantly developed by Pinker. It has been popularly contextualized within the so-called "Past-Tense Debate," which was sparked by Rumelhart and McClelland's 1986 connectionist model of the production of regular and irregular verbs. In essence, the Words and Rules theory states that past-tense forms of verbs arise from both declarative memory (as words) and procedural systems (from rules). Main ideas In his book, Pinker "tries to illuminate the nature of language and mind by choosing a single phenomenon and examining it from every angle imaginable." His analysis reflects his view that language and many other aspects of human nature are innate evolutionary-psychological adaptations. Most of the book examines studies conducted on the form and frequency of grammatical errors (such as overgeneralization in past-tense formation) in English (and to a lesser extent in German) as well as the speech of brain-damaged persons with selective aphasia. Pinker discusses neuropsychological dissociations in two types of aphasia: anomia and agrammatism. Anomic patients often produce fluent and generally grammatical speech despite having difficulty retrieving and recognizing words, which implies the lexicon is "more impaired than grammatical combination." Some patients also have jargon aphasia in which they speak their own neologisms (e.g. "nose cone" for "phone call") and often add regular suffixes onto their jargon, which suggests the area of the brain that computes regular inflection is distinct from the area in which words are processed. In contrast, agrammatic patients have difficulty assembling words into phrases and sentences and applying correct grammatical suffixes (either omitting them altogether or using the wrong one) and are therefore unable to produce fluent grammatical sequences. For example, when reading a list of words patients might read smiled as "smile" and wanted as "wanting"; the reason being that regularly inflected words are computed by rules as they are read, and that agrammatic patients have damage to the machinery that does the computing. However, when reading irregular past-tense forms and plurals, patients with impaired grammatical processing make fewer errors as they are still able to match irregular verbs against memory as wholes. The title, Words and Rules, refers to a model Pinker believes best represents how words are represented in the mind. He writes that words are either stored directly with their associated