Summary.
The obversion of an I proposition.
1. Principle:
Same as with A.
2. Rule:
Negate the predicate and change the I to an O.
3. Process illustrated.
| The Original Proposition (I) | The Obverse (O) |
| Some water is pure. | Some water is not impure. |
| Some curves are perfect. | Some curves are not imperfect. |
| Some friends are loyal. | Some friends are not disloyal. |
| Some men are true. | Some men are not not-true. |
| Some precious stones are imperfect. | Some precious stones are not perfect. |
| Some plants are not-trees. | Some plants are not trees. |
| Some boys are not-honest. | Some boys are not honest. |
It must be borne in mind that when “not” is used without the hyphen it makes the proposition negative, because when “unhyphened,” “not” must be thought of in connection with the copula and not in connection with the predicate; while “not” attached to the predicate with a hyphen simply makes the predicate negative without affecting the quality of the proposition; e. g., “Some plants are not trees” is a negative proposition, while “Some plants are not-trees” is an affirmative proposition with a negative predicate.
It may not be clearly seen how it is possible, by following the rule given, to pass from such a proposition as “Some plants are not-trees,” to “Some plants are not trees.” Let us illustrate the steps: