Presentation on theme: "How can it be a syllogism if it doesn’t look like an A,E, I, or O statement? Translating “Ordinary” Sentences into the Standard Forms."— Presentation transcript:
How can it be a syllogism if it doesn’t look like an A,E, I, or O statement? Translating “Ordinary” Sentences into the Standard Forms
Clearly identify the subject & predicate “Seldom have sailors had such acclaim.” Becomes: Sailors have seldom had such acclaim. OR Sailors are persons who have seldom had such acclaim. All take great risks who put their eggs into one basket. Becomes: All persons who put their eggs in one basket are persons who take great risks.
Supply the missing quantifier Unless it is clear from the context that “some” is intended, the rule is that “all” is meant. Psychotics are dangerous. Should be: ALL psychotics are dangerous. Americans are great sprinters. Should be: SOME Americans are great sprinters.
Add the missing complement. Sometimes a complement needs to be added to an adjective or to a describing phrase. Some lions are docile (since we cannot point to a “docile”) becomes: Some lions are docile creatures (or animals)
Supply the missing Copula Dogs bark. Should be: All dogs are barking animals. Some ancients believed in devils. Should be: Some ancient peoples are people who believed in devils.
Exclusive Sentences E.g., sentences beginning with “only” or “none but” Only men are priests. Cannot mean: “that all men are priests.” Only men are priests, means: “All priests are men.” THE RULE: Drop the “only” or “none but” Add “all” as the quantifer Reverse the subject and predicate None but adults are admitted. Means: All those admitted persons are adults.
Negative Sentences Words such as “nothing”, “none”, “no one” are to be replaced with the quantifier “no”. e.g. None of the damned is happy. Becomes: No person who is damned is a happy person. Nothing human frightens me. Becomes: No human beings are things that frighten me.
More Negative sentences If the sentences says: “All (subject) are not (the predicate)” or “Every...not...” follow the rule: “All...not...” sentences should be interpreted as O sentences unless they are CLEARLY E sentences. i.e., “All... Not...” Becomes “Some... Not....” All Germans are not Nazis, DOES NOT mean “No Germans are Nazis” (E) But rather: “Some Germans are not Nazis.” (O)
Exceptive Sentences Sentences containing “except” cannot be translated into any one of A,E, I, O sentences. “Everyone except women may attend.” Means something expressed by: 1) All who are not women may attend. (A) (All who are non-women may attend) and 2) No women may attend. (E)
Exceptive Sentences (cont.) Since a syllogism requires only 3 sentences, we cannot use both in our syllogism. The rule: either the A or E sentence may be used, but not both. An argument which contains an exceptive sentence and which is valid will remain valid if the exceptive sentence is interpreted either as an A sentence or as an E sentence. See the next slide:
Another exceptive example All students except senior students take Physical Education. Means: No seniors take Physical Education. And All other students take Physical Education. Better yet: All non-seniors take Physical Education.
If it has: “Anyone, anything, Whoever, It translates into an A sentence. Anyone who comes must participate. Anything which comes must participate. Whoever comes must participate. Whatever comes must participate. Everyone who comes must participate. If anyone comes he must participate. The person who comes must participate Becomes… All who come must participate. All persons who come must participate. All who come are people who participate.