Adapted from Lewis Carroll’s Symbolic Logic (1896)

“Classification,” or the formation of Classes, is a Mental Process, in which we imagine that we have put together, in a group, certain Things. Such a group is called a “Class.” This Process may be performed in three different ways, as follows:

(1) We may imagine that we have put together all Things. The Class so formed (i.e. the Class "Things") contains the whole Universe.

(2) We may think of the Class "Things," and may imagine that we have picked out from it all the Things which possess a certain Adjunct not possessed by the whole Class. This Adjunct is said to be “peculiar” to the Class so formed. In this case, the Class "Things" is called a “Genus” with regard to the Class so formed: the Class, so formed, is called a 'Species' of the Class "Things": and its peculiar Adjunct is called its “Differentia.”

As this Process is entirely Mental, we can perform it whether there is, or is not, an existing Thing which pos- sesses that Adjunct. If there is, the Class us said to be “Real;” if not, it is said to be “Unreal,” or “Imaginary.”

[For example, we may imagine that we have picked out, from the Class "Things," all the Things which possess the Adjunct "material, artificial, consisting of houses and street"; and we may thus form the Real Class "towns." Here we may regard "Things" as a Genus, "Towns" as a Species of Things, and "material, artificial, consisting of houses and streets" as its Differentia. Again, we may imagine that we have picked out all the Things which possess the Adjunct "weighing a ton, easily lifted by a baby"; and we may thus form the Imaginary Class "Things that weigh a ton and are easily lifted by a baby."]

(3) We may think of a certain Class, not the Class "Things," and may imagine that we have picked out from it all the Members of it which possess a certain Adjunct not possessed by the whole Class. This Adjunct is said to be “peculiar” to the smaller Class so formed. In this case, the Class thought of is called a “Genus” with regard to the smaller Class picked out from it: the smaller Class is called a “Species” of the larger: and its peculiar Adjunct is called its “Differentia.”

[For example, we may think of the Class "towns," and imagine that we have picked out from it all the towns which possess the Attribute "lit with gas"; and we may thus form the Real Class "towns lit with gas." Here may regard "Towns" as a Genus, "Towns lit with gas" as a Species of Towns, and "lit with gas" as its Differentia. If, in the above example, we were to alter "lit with gas" into "paved with gold," we should get the Imaginary Class "towns paved with gold."]

A Class, containing only one Member is called an “Individual.”

[For example, the Class "towns having four million inhabitants," which Class contains only one Member, viz. "London."]

Hence, any single Thing, which we can name so as to distinguish it from all other Things, may be regarded as a one-Member Class.

[Thus "London" may be regarded as the one-Member Class, picked out from the Class "towns," which has, as its Differentia, "having four million inhabitants."]

A Class, containing two or more Members, is sometimes regarded as one single Thing. When so regarded, it may possess an Adjunct which is not possessed by any Member of it taken separately.

[Thus, the Class "The soldiers of the Tenth Regiment," when regarded as one single Thing, may possess the Attribute "formed in square," which is not possessed by any Member of it taken separately.]

With what is the claim in the first paragraph that "Classification [...] is a mental process" supported?

Adapted from Mark Twain’s “A Defense of General Funston” (1802)

We are made, brick by brick, of influences, patiently built up around the framework of our born dispositions. It is the sole process of construction; there is no other. Every man and woman and child is an influence; a daily and hourly influence which never ceases from work, and never ceases from affecting for good or evil the characters about it--some contributing gold-dust, some contributing trash-dust, but in either case helping on the building, and never stopping to rest. The shoemaker helps to build his two-dozen associates; the pickpocket helps to build his four dozen associates; the village clergyman helps to build his five hundred associates; the renowned bank-robber's name and fame help to build his hundred associates and three thousand persons whom he has never seen; the renowned philanthropist's labors and the benevolent millionaire's gifts move to kindly works and generous outlays of money a hundred thousand persons whom they have never met and never will meet; and to the building of the character of every individual thus moved these movers have added a brick. The unprincipled newspaper adds a baseness to a million decaying character-fabrics every day; the high-principled newspaper adds a daily betterment to the character-fabric of another million. The swiftly-enriched wrecker and robber of railway systems lowers the commercial morals of a whole nation for three generations. A Washington, standing upon the world's utmost summit, eternally visible, eternally clothed in light, a serene, inspiring, heartening example and admonition, is an influence which raises the level of character in all receptive men and peoples, alien and domestic; and the term of its gracious work is not measurable by fleeting generations, but only by the lingering march of the centuries.

Washington was more and greater than the father of a nation, he was the Father of its Patriotism--patriotism at its loftiest and best; and so powerful was the influence which he left behind him, that that golden patriotism remained undimmed and unsullied for a hundred years, lacking one; and so fundamentally right-hearted are our people by grace of that long and ennobling teaching, that to-day, already, they are facing back for home, they are laying aside their foreign-born and foreign-bred imported patriotism and resuming that which Washington gave to their fathers, which is American and the only American--which lasted ninety-nine years and is good for a million more. Doubt--doubt that we did right by the Filipinos--is rising steadily higher and higher in the nation's breast; conviction will follow doubt. The nation will speak; its will is law; there is no other sovereign on this soil; and in that day we shall right such unfairnesses as we have done. We shall let go our obsequious hold on the rear-skirts of the sceptred land-thieves of Europe, and be what we were before, a real World Power, and the chiefest of them all, by right of the only clean hands in Christendom, the only hands guiltless of the sordid plunder of any helpless people's stolen liberties, hands recleansed in the patriotism of Washington, and once more fit to touch the hem of the revered Shade's garment and stand in its presence unashamed. It was Washington's influence that made Lincoln and all other real patriots the Republic has known; it was Washington's influence that made the soldiers who saved the Union; and that influence will save us always, and bring us back to the fold when we stray.

And so, when a Washington is given us, or a Lincoln, or a Grant, what should we do? Knowing, as we do, that a conspicuous influence for good is worth more than a billion obscure ones, without doubt the logic of it is that we should highly value it, and make a vestal flame of it, and keep it briskly burning in every way we can--in the nursery, in the school, in the college, in the pulpit, in the newspaper--even in Congress, if such a thing were possible.

The proper inborn disposition was required to start a Washington; the acceptable influences and circumstances and a large field were required to develop and complete him.

What is the main weakness in the author's argumentation?