問57
頻出度★★☆
推論に関する次の記述中の a，b に入れる字句の適切な組合せはどれか。 [ a ] は，個々の事例を基にして，事例に共通する規則を得る方法であり，得られた規則は [ b ] 。
令和4年度 ITパスポート試験 問57
テクノロジ系基礎理論 › 情報に関する理論
This question's explanation and your answers so far.
解説
問 57
Incorrectア
Although b “may not hold” is correct as a property of inductive reasoning, treating a as deductive reasoning is wrong. Deductive reasoning is a method that derives an individual conclusion from a general premise (rule), which is the opposite direction of the statement’s “deriving a common rule from individual cases” = inductive reasoning. a does not fit.
Incorrectイ
Treating a as deductive reasoning is wrong (the statement describes inductive reasoning, which derives a rule from cases). In addition, b “always holds” also does not apply to an inductive rule, which is a generalization from cases. Both a and b do not fit.
- ウ
正解 Blank a — “a method that derives a rule common to individual cases based on those individual cases” — is a description of inductive reasoning (induction). Observing many individual cases and drawing out a general rule or law common to them is the defining feature of inductive reasoning. Blank b, on the other hand, asks about the nature of the rule obtained by inductive reasoning. Because inductive reasoning is only a generalization from a finite number of cases, if an unobserved case (a counterexample) exists the rule can be overturned, so it “may not hold.” Therefore the combination a = inductive reasoning / b = may not hold, that is ウ, is the correct answer.
Incorrectエ
a = inductive reasoning is correct, but b “always holds” is wrong. An inductive rule is a generalization from a finite number of cases, so it can be overturned by a counterexample. “Always holds” is a property of deductive reasoning — if the premises are correct the conclusion is necessarily correct — and does not apply to induction. b does not fit.
ここがポイント
- Inductive reasoning (induction) = a method that derives a common rule based on individual cases. The rule obtained is a generalization from a limited number of cases, so it can be overturned by a counterexample (it does not always hold).
- Deductive reasoning (deduction) = a method that derives an individual conclusion from a general premise or rule. If the premises are correct, the conclusion necessarily holds. The two are distinguished by this “direction” and this “guarantee of holding.”
用語