Universal affirmative: Difference between revisions

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(Created page with "A universal affirmative is a categorical statement taking the form: “Every A is B.” where A and B are predicates. In the language of predicate logic, thi...")
 
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[[Universal affirmative]]s can only be partially converted.  “All of Alma Cogan is dead, but only some of the class of dead people are Alma Cogan.”
[[Universal affirmative]]s can only be partially converted.  “All of Alma Cogan is dead, but only some of the class of dead people are Alma Cogan.”


For example, given the premise, "all fish live underwater" and "all mackerel are fish", my wife will conclude, not that "all mackerel live underwater", but that "if she buys kippers it will not rain", or that "trout live in trees", or even that "I do not love her any more."  
As Monty Python had it, given the premise, "all fish live underwater" and "all mackerel are fish", one cannot conclude that "all mackerel live underwater", or that "if she buys kippers it will not rain", or that "trout live in trees", much less that "I do not love you any more."  


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*[[Correlation]] and [[causation]]
*[[Correlation]] and [[causation]]