A deductive argument is invalid if :
2023
A deductive argument is invalid if :
- A.
its premises and conclusions are false.
- B.
its premises are all false but conclusions are true.
- C.
its premises are all true but conclusions are false.
- D.
its premises and conclusions are all true.
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Correct answer: C
Definition of validity: A deductive argument is valid if and only if whenever all its premises are true, the conclusion must also be true. निगमनात्मक तर्क का अर्थ: यदि इसके सभी आधारतथ्य सच हों तो निष्कर्ष भी अनिवार्य रूप से सच होना चाहिए। What makes an argument invalid: An argument is invalid exactly when it is possible for all premises to be true while the conclusion is false. क्यों अप्रामाणित कहते हैं: यदि आधारतथ्य सच्चे होने पर भी निष्कर्ष असत्य हो सकता है, तो तर्क अप्रामाणित है। Counterexample (shows invalidity): Consider the premises 'All dogs are mammals' and 'All mammals are animals.' These premises are true, but the conclusion 'All animals are dogs' is false. Since there is a possible situation where the premises are true and the conclusion is false, the argument is invalid.