34: On the Causal Proposition
On the Causal Proposition of a disjunctive to the whole disjunctive proposition. But the converse commits a fallacy of consequent—except that sometimes there is some special reason that blocks the fallacy of consequent.
Similarly, it is valid to argue from a disjunctive proposition along with the negation of one of its parts to the other part. For example, this follows: 'Socrates is a man or a donkey; Socrates is not a donkey; therefore Socrates is a man'.
34: On the Causal Proposition A causal proposition is one which is composed of two or more categoricals joined by the conjunction 'since' or by some equivalent. Hence, this is a causal proposition: 'Since Socrates is a man,
Socrates is an animal'. This is also a causal proposition: 'Socrates is working, in order that he might be healthy'. For it is equivalent to 'Socrates is working, since he wants to be healthy'. Likewise, this is a causal proposition: 'Socrates takes a walk after dinner, lest he become ill'. For it is equivalent to 'Since Socrates does not want to become ill, he takes a walk after dinner'. Similarly, this is a causal proposition: 'Socrates becomes warm insofar as he moves'. For it is equivalent to: 'Since Socrates moves, he becomes warm'.
Now for the truth of a causal proposition it is required that each part be true and, besides this, that the antecedent be the cause of the consequent. Therefore, the proposition 'Socrates is white, since Plato is white' is not true. For although each of its parts is true, still the following is not true: 'Socrates is white in virtue of the fact that Plato is white'. Therefore, the proposition in question is false.
It should be noted that 'cause' is being used here in a loose sense and not in the strict sense. For it is not required for the On the Causal Proposition truth of a causal proposition that the one proposition be the cause of the other proposition's coming into being. Rather, it is sufficient that it express a cause which is required for the other proposition's being true, as in 'The wood becomes hot, since fire is present in it'. For by means of that antecedent, 'Fire is present in it', there is expressed a cause without which 'The wood becomes hot' would not be true. Therefore, the causal proposition in question is true. Or else it is required that the one proposition be prior to the other in such a way that the predicate of the antecedent is predicated of its subject prior to the predicate'of its subject. Accordingly, this can be true: 'An isosceles has three etc., since a triangle has three, etc.'.
It should be noted that 'cause' is being used loosely here for a per se cause or a per accidens cause, or for a voluntary cause or a natural cause.
From these remarks it is clear that all propositions such as the following are false: 'A donkey is risible, since it is a man', 'Every man sins, since he has a free will', etc.
Hence, in order for a causal proposition to be necessary it is required that both parts be necessary. But for a causal proposition to be impossible neither the impossibility nor the falsity of one of the parts is required. Rather, it is sufficient that the antecedent cannot be the cause of the consequent—taking 'cause' in the way noted above.
And it should be noted that 'antecedent' here does not designate what comes first in word order. Rather, the antecedent is the proposition which immediately follows the conjunction 'since'.
Similarty, in order for a causal proposition to be possible it is required that each part be possible. But this is not sufficient, just as the necessity of each part is not sufficient in order for sucha proposition to be necessary.
From what has beensaid it is clear that there is a valid consequence from a causal proposition to one of its parts—but not conversely. Similarly, there is a valid consequence from a causal proposition to a conjunctive proposition—but not conversely.
Hence, this is valid: 'Every man sins, since he has a free will; therefore every man sins and every man hasa free will'. But the converse is not valid.