Structure of a deductive argument


I wonder if this is true for all deductive arguments,

a deductive argument must have at least one premise where the term "ALL" or "NONE" or an equivalent word appears

Is it true? Can anyone show any counterexample?

NB: By equivalent I meant word or semantics. For example, "Every" can be used instead of "All" etc.

Sazzad Hissain Khan

Posted 2021-01-10T18:24:02.953

Reputation: 236

1"or equivalence"? what does it mean? – Mauro ALLEGRANZA – 2021-01-10T18:59:07.080


If you refer to Aristotle's Syllogism the answer is YES. No valid deduction with only particular premises.

– Mauro ALLEGRANZA – 2021-01-10T19:01:04.743

by equivalence i meant word or semantics. For example, "Every" can be used instead of "All". . etc. @MauroALLEGRANZA – Sazzad Hissain Khan – 2021-01-10T19:01:11.417

If so, your question is quite unclear... – Mauro ALLEGRANZA – 2021-01-10T19:01:18.363

@MauroALLEGRANZA I updated the post, if you could please improve it – Sazzad Hissain Khan – 2021-01-10T19:07:12.810

6On the other hand, if you are referring to anything other than Aristotle's syllogisms, then the answer is no. Mike is a mechanic; therefore somebody is a mechanic. My next door neighbour has a cat and a dog; therefore my next door neighbour has a cat. The card up my sleeve is an ace or a king; it is not a king; therefore, it is an ace. Etc. – Bumble – 2021-01-10T19:31:16.777

OBJECTIVELY that is 100 percent true but not fully complete. We need to distinguish Philosophy from Psychology here. JUST because you see only one premise doesn’t mean there is no second premise. Thinking like that is a sign a person being too psychological. All deductive reasoning REQUIRES a quantifier and a minimum of TWO PREMISES to reach a conclusion. Because someone hides a premise means ZILCH —absolutely NOTHING. The concept is present REGARDLESS. A Quantifier can be hidden as in the proposition “Dogs are animals.” Does the word ALL appear in the sentence? You know it belongs there!! – Logikal – 2021-01-10T20:19:12.127

Stop being so literal. Because someone hides a quantifier word or hides a premise DOES NOT mean there are none. If you understand the concepts of deductive reasoning you will be able to FILL IN THE REQUIRED parts. Some deductive reasoning is outside of mathematics. Aristotelian logic is outside of mathematics. An argument with missing premises is called an Enthymeme: All men are mortal; therefore Socrates is mortal. Clearly we can figure out what the missing premise was: Socrates is a man. The proposition “women are not snakes” would be correctly written as “No women are snakes.” – Logikal – 2021-01-10T20:26:10.957

1I had not realized it, but you are correct. Every valid syllogism contains at least one premise which is an A statement (All X are Y) or an E statement (No X are Y). Thank you. – Mark Andrews – 2021-01-11T03:12:08.203


  • All deductions must contain an "all" statement 2. These three sentences contain an "all" statement 3. These three sentences are a deduction.
  • < – armand – 2021-01-11T05:22:55.653

    No answers