e to group your acquaintances into the two Classes, men that
you _would_ like to be seen with, and men that you would _not_ like to
be seen with, do you think the latter group would be so _very_ much the
larger of the two?

For the purposes of Symbolic Logic, it is so _much_ the most convenient
plan to regard the two sub-divisions, produced by Dichotomy, on the
_same_ footing, and to say, of any Thing, either that it "is" in the
one, or that it "is" in the other, that I do not think any Reader of
this book is likely to demur to my adopting that course.

pg173
Sec. 4.

_The theory that "two Negative Premisses prove nothing"._

This I consider to be _another_ craze of "The Logicians", fully as
morbid as their dread of a negative Attribute.

It is, perhaps, best refuted by the method of _Instantia Contraria_.

Take the following Pairs of Premisses:--

"None of my boys are conceited;
None of my girls are greedy".

"None of my boys are clever;
None but a clever boy could solve this problem".

"None of my boys are learned;
Some of my boys are not choristers".

(This last Proposition is, in _my_ system, an _affirmative_ one, since I
should read it "are not-choristers"; but, in dealing with "The
Logicians," I may fairly treat it as a _negative_ one, since _they_
would read it "are-not choristers".)

If you, dear Reader, declare, after full consideration of these Pairs of
Premisses, that you cannot deduce a Conclusion from _any_ of
them----why, all I can say is that, like the Duke in Patience, you "will
have to be contented with our heart-felt sympathy"! [See Note (C), p.
196.]

Sec. 5.

_Euler's Method of Diagrams._

Diagrams seem to have been used, at first, to represent _Propositions_
only. In Euler's well-known Circles, each was supposed to contain a
class, and the Diagram consisted of two circles, which exhibited the
relations, as to inclusion and exclusion, existing between the two
Classes.

_____
_/ ___ \_
/ / y \ \
| \___/ |
\_ x _/
\_____/

Thus, the Diagram, here given, exhibits the two Classes, whose
respective Attributes are x and y, as so related to each other that the
following Propositions are all simultaneously true:--"All x are y", "No
x are not-y", "Some x are y", "Some y are not-x", "Some not-y are
not-x", and, of course, the Converses of th