The Death of Marcus Aurelius

The Death of Marcus Aurelius

Friday, August 12, 2022

Wisdom from the Early Stoics, Zeno of Citium 50


The first kind of indemonstrable statement is that in which the whole argument is constructed of a hypothetical proposition and the clause with which the hypothetical proposition begins, while the final clause is the conclusion; as e.g. "If the first, then the second; but the first is, therefore the second is." 

The second is that which employs a hypothetical proposition and the contradictory of the consequent, while the conclusion is the contradictory of the antecedent; e.g. "If it is day, it is light; but it is night, therefore it is not day." Here the minor premise is the contradictory of the consequent; the conclusion the contradictory of the antecedent. 

The third kind of indemonstrable employs a conjunction of negative propositions for the major premise and one of the conjoined propositions for the minor premise, concluding thence the contradictory of the remaining proposition; e.g. "It is not the case that Plato is both dead and alive; but he is dead, therefore Plato is not alive." 

The fourth kind employs a disjunctive proposition and one of the two alternatives in the disjunction as premises, and its conclusion is the contradictory of the other alternative; e.g. "Either A or B; but A is, therefore B is not." 

The fifth kind is that in which the argument as a whole is constructed of a disjunctive proposition and the contradictory of one of the alternatives in the disjunction, its conclusion being the other alternative; e.g. "Either it is day or it is night; but it is not night, therefore it is day." 

From a truth a truth follows, according to the Stoics, as e.g. "It is light" from "It is day"; and from a falsehood a falsehood, as "It is dark" from "It is night," if this latter be untrue. 

Also a truth may follow from a falsehood; e.g. from "The earth flies" will follow "The earth exists"; whereas from a truth no falsehood will follow, for from the existence of the earth it does not follow that the earth flies aloft. 

Diogenes Laërtius, 7.80-81 



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