Topic 6 Reading Exercises from:
Copi, Irving M. Introduction to Logic, 14th Edition. Routledge.
Rewrite each of the following syllogisms in standard form, and name its mood and
figure. (Procedure: first, identify the conclusion; second, note its predicate term, which is the
major term of the syllogism; third, identify the major premise, which is the premise containing
the major term; fourth, verify that the other premise is the minor premise by checking to see that
it contains the minor term, which is the subject term of the conclusion; fifth, rewrite the
argument in standard form—major premise first, minor premise second, conclusion last; sixth,
name the mood and figure of the syllogism.)
No nuclear-powered submarines are commercial vessels, so no warships are commercial vessels,
because all nuclear-powered submarines are warships.
The conclusion is “No warships are commercial vessels.”
“Commercial vessels” is the predicate term of this conclusion and is therefore the
Step 2. major term of the syllogism.
The major premise, the premise that contains this term, is “No nuclear-powered
Step 3. submarines are commercial vessels.”
The remaining premise, “All nuclear-powered submarines are warships,” is indeed the
Step 4. minor premise, because it does contain the subject term of the conclusion, “warships.”
Step 5. In standard form this syllogism is written thus:
No nuclear-powered submarines are commercial vessels.
All nuclear-powered submarines are warships.
Therefore no warships are commercial vessels.
The three propositions in this syllogism are, in order, E, A, and E. The middle term,
“nuclear-powered submarines,” is the subject term of both premises, so the syllogism
Step 6. is in the third figure. The mood and figure of the syllogism therefore are EAE-3.
2. Some evergreens are objects of worship, because all fir trees are evergreens, and some objects
of worship are fir trees.
3. All artificial satellites are important scientific achievements; therefore some important
scientific achievements are not U.S. inventions, inasmuch as some artificial satellites are not U.S.
4. No television stars are certified public accountants, but all certified public accountants are
people of good business sense; it follows that no television stars are people of good business
5. Some conservatives are not advocates of high tariff rates, because all advocates of high tariff
rates are Republicans, and some Republicans are not conservatives.
6. All CD players are delicate mechanisms, but no delicate mechanisms are suitable toys for
children; consequently, no CD players are suitable toys for children.
7. All juvenile delinquents are maladjusted individuals, and some juvenile delinquents are
products of broken homes; hence some maladjusted individuals are products of broken homes.
8. No stubborn individuals who never admit a mistake are good teachers, so, because some wellinformed people are stubborn individuals who never admit a mistake, some good teachers are not
9. All proteins are organic compounds, hence all enzymes are proteins, as all enzymes are
10. No sports cars are vehicles intended to be driven at moderate speeds, but all automobiles
designed for family use are vehicles intended to be driven at moderate speeds, from which it
follows that no sports cars are automobiles designed for family use.
Write out each of the following syllogistic forms, using S and P as the subject and predicate
terms of the conclusion, and M as the middle term. (Refer to the chart of the four syllogistic
figures, if necessary, on p. 235.) Then test the validity of each syllogistic form using a Venn
We are told that this syllogism is in the first figure, and therefore the middle term, M, is the
subject term of the major premise and the predicate term of the minor premise. (See chart on p.
235.) The conclusion of the syllogism is an E proposition and therefore reads: No S is P. The
first (major) premise (which contains the predicate term of the conclusion) is an A proposition,
and therefore reads: All M is P. The second (minor) premise (which contains the subject term of
the conclusion) is an E proposition and therefore reads: No S is M. This syllogism therefore
reads as follows:
All M is P.
No S is M.
Therefore no S is P.
Tested by means of a Venn diagram, as in Figure 6-10, this syllogism is shown to be invalid.
Put each of the following syllogisms into standard form, name its mood and figure, and test its
validity using a Venn diagram:
1.Some reformers are fanatics, so some idealists are fanatics, because all reformers are idealists.
2.Some philosophers are mathematicians; hence some scientists are philosophers, because all
scientists are mathematicians.
3.Some mammals are not horses, for no horses are centaurs, and all centaurs are mammals.
4.Some neurotics are not parasites, but all criminals are parasites; it follows that some neurotics
are not criminals.
5.All underwater craft are submarines; therefore no submarines are pleasure vessels, because no
pleasure vessels are underwater craft.
Identify the rule that is broken by any of the following syllogisms that are invalid, and name the
fallacy that is committed:
All chocolate éclairs are fattening foods, because all chocolate éclairs are rich desserts, and some
fattening foods are not rich desserts.
In this syllogism the conclusion is affirmative (“all chocolate éclairs are fattening foods”),
while one of the premises is negative (“some fattening foods are not rich desserts”). The
syllogism therefore is invalid, violating the rule that if either premise is negative the
conclusion must also be negative, thereby committing the fallacy of drawing an affirmative
conclusion from a negative premise.
2. All inventors are people who see new patterns in familiar things, so all inventors are
eccentrics, because all eccentrics are people who see new patterns in familiar things.
3. Some snakes are not dangerous animals, but all snakes are reptiles, therefore some dangerous
animals are not reptiles.
4. Some foods that contain iron are toxic substances, for all fish containing mercury are foods
that contain iron, and all fish containing mercury are toxic substances.
5. All opponents of basic economic and political changes are outspoken critics of the liberal
leaders of Congress, and all right-wing extremists are opponents of basic economic and political
changes. It follows that all outspoken critics of the liberal leaders of Congress are right-wing
Purchase answer to see full