Ch 3: Clarity
ambiguity: when it is unclear which word or sentence structure a speaker intends to express because two words look or sound the same. (That is, the same spoken or written forms express different meanings.) See lexical ambiguity and syntactic ambiguity.
bare plurals: the use of a plural noun phrase without a determiner (e.g., “Canadians started laughing” instead of “Some Canadians started laughing”).
borderline cases: cases where it is unclear whether a category applies to an individual, and not because we need more facts about the individual (e.g., you might sit on something that seems somewhat like a chair and somewhat like a stool).
conclusion: the statement expressing the belief that our argument is meant to support.
conclusion indicators: expressions that often signal the presence of a conclusion (e.g., therefore, so, thus, as a result).
deduction: arriving at a conclusion on the basis of beliefs that entail it.
deductive argument: an argument whose premises are presented as entailing its conclusion.
deductive validity: an argument is deductively valid when its premises entail its conclusion.
directly perceptual beliefs: beliefs that are supported directly by perception, rather than by other beliefs.
entailment: one or more premises entail a conclusion when they meet this condition: if the premises were true, the conclusion would also have to be true.
generality: an expression's generality is a matter of how many things it applies to. Generality is distinct from both ambiguity and vagueness.
implicit premise: a claim that is left unstated but which is taken for granted in making an argument.
induction: arriving at a conclusion on the basis of beliefs that support but do not entail it.
inductive argument: an argument whose premises are presented as providing support for its conclusion but not entailing it. In these cases, the truth of the premises is not supposed to guarantee the truth of the conclusion with certainty. Instead, the premises are just intended to provide support for the conclusion.
inference: a single step in a line of reasoning. We take these steps in our reasoning to arrive at a belief, because we take that belief to be supported by other beliefs.
interim conclusion: a conclusion that is supported by some premises in the argument, and that also provides support for a further conclusion of the argument.
lexical ambiguity: when it is unclear which of many possible words, which share the same written or spoken form, the speaker is intending to express (e.g., the absent-minded professor was arrested for not finishing his sentence).
premise indicators: expressions that often signal the presence of a premise (e.g., because, since, as, given that, seeing as).
premises: the statements expressing the supporting beliefs in an argument; i.e. those intended to support the conclusion.
principle of charity: when interpreting an argument, we should always try to identify the best version of the argument that the author could plausibly have intended.
self-evident beliefs: beliefs that are so obviously true that we don't know how we would even go about supporting them (e.g., “1+1=2” or “green is a color”).
sharp borders fallacy: assuming that real and useful distinctions with clear cases on either side can't also have borderline cases.
standard form: a representation of an argument in terms of an ordered series of declarative sentences, with each premise and the conclusion (or conclusions) labeled. Next to each conclusion, it should be noted which premises directly support that conclusion and whether that support is inductive or deductive.
suppositional strength: a measure of how well the premises connect to the conclusion of an argument. The suppositional strength of an argument is a matter of how much evidence the premises would provide for the conclusion if we suppose them to be true.
syntactic ambiguity: when it is unclear which sentence structure a speaker intends to express (e.g., man shoots neighbor with machete).
vagueness: when a word, concept, or distinction has borderline cases (i.e., where it is unclear whether the word/concept/distinction applies).