Method of Diagrams.
[SL4-A]Solutions for § 4, Nos. 1–12.

1.
No m are x′;
All m′ are y.

∴ No x′ are y′.
[pg137]
2.
No m′ are x;
Some m′ are y′.

∴ Some x are y′.

3.
All m′ are x;
All m′ are y′.

∴ Some x are y′.

4.
No x′ are m′;
All y′ are m.
There is no Conclusion.

5.
Some m are x′;
No y are m.

∴ Some x′ are y′.

6.
No x′ are m;
No m are y.
There is no Conclusion.

7.
No m are x′;
Some y′ are m.

∴ Some x are y′.

8.
All m′ are x′;
No m′ are y.

∴ Some x′ are y′.
[pg138]
9.
Some x′ are m′;
No m are y′.
There is no Conclusion.

10.
All x are m;
All y′ are m′.

∴ All x are y;
All y′ are x′.

11.
No m are x;
All y′ are m′.
There is no Conclusion.

12.
No x are m;
All y are m.

∴ All y are x′.
[SL5-A]Solutions for § 5, Nos. 1–12.

1. I have been out for a walk;
I am feeling better.

Univ. is “persons”; m = the Class of I’s; x = persons who have been out for a walk; y = persons who are feeling better.


All m are x;
All m are y.

∴ Some x are y.

i.e. Somebody, who has been out for a walk, is feeling better.

[pg139] 2. No one has read the letter but John;
No one, who has not read it, knows what it is about.

Univ. is “persons”; m = persons who have read the letter; x = the Class of Johns; y = persons who know what the letter is about.