Which of the Six Rules for determining the validity of categorical syllogism does the following categorical syllogism violate?:
Some nebulas are clouds of gas.
Some clouds of gas are objects invisible to the naked eye.
Therefore, some objects invisible to the naked eye are nebulas.

Question

Which of the Six Rules for determining the validity of categorical syllogism does the following categorical syllogism violate?:

Some nebulas are clouds of gas.

Some clouds of gas are objects invisible to the naked eye.

Therefore, some objects invisible to the naked eye are nebulas.

Answer

If
one premise is negative,
the conclusion must be negative; and if the conclusion is negative, then one
premise must be negative.

Answer

If
a term is distributed
in the conclusion, the it must be distributed in the premise.

Answer

A
syllogism must have only three terms
(not three words, but terms).

Answer

No
syllogism can have two negative
premises.

Answer

The
middle term must be distributed
at least once.

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