_The Universal Affirmative_ (symbol A) proposition is converted by Limitation, or by a change of quality from universal to particular. The predicate not being "distributed" in the convertend, we must not distribute it in the converse by saying "_all_." Thus in this case we must convert the proposition, "all men are mortal" (A), into "some mortals are men" (I). _The Universal Negative_ (symbol E) is converted by Simple Conversion, in which there is no change in either quality or quantity. For since both terms of "E" are distributed, they may both be distributed in the converse without violating the law of conversion. Thus "No man is mortal" is converted into: "No mortals are men." "E" is converted into "E." _The Particular Affirmative_ (symbol I) is also converted by Simple Conversion in which there is no change in either quality or quantity. For since neither term is distributed in "I," neither term may be distributed in the converse, and the latter must remain "I." For instance; the proposition: "Some men are mortal" is converted into the proposition, "Some mortals are men." _The Particular Negative_ (symbol O) is converted by Conversion by Negation, in which the quality is changed but not the quantity. Thus in converting the proposition: "Some men are not mortal," we must _not_ say "some mortals are not men," for in so doing we would distribute _men_ in the predicate, where it is not distributed in the convertend. Avoiding this, _we transfer the negative particle from the copula to the predicate_ so that the convertend becomes "I" which is converted by Simple Conversion. Thus we transfer "Some men are not mortal" into "Some men are not-mortal" from which we easily convert (by simple Conversion) the proposition: "Some not-mortals are men." It will be well for students, at this point, to consider the three following Fundamental Laws of Thought as laid down by the authorities, which are as follows: _The Law of Identity_, which states that: "The same quality or thing is always the same quality or thing, no matter how different the conditions in which it occurs." _The Law of Contradiction_, which states that: "No thing can at the same time and place both be and not be." _The Law of Excluded Middle_, which states that: "Everything must either be or not be; there is no other alternative or middle course." Of these laws, Prof. Jevons, a noted authority, says: "Students are seldom able to see at first their full meaning and importance. All arguments may be explained when these self-evident laws are granted; and it is not too much to say that the whole of logic will be plain to those who will constantly use these laws as the key." CHAPTER XI. INDUCTIVE REASONING