“Questions of Past Fact may be looked at in the following ways: First, that if the less likely of two things has occurred, the more likely must have occurred also. That if one thing that usually follows another has happened, then that other thing has happened; that, for instance, if a man has forgotten a thing, he has also once learnt it. That if a man had the power to wish and do a thing, he has done it; for everyone does do whatever he intends to do whenever he can do it, there being nothing to stop him. That, further, he has done the thing in question either if he intended it and nothing external prevented him; or if he had the power to do it and his heart was set upon it—for people as a rule do what they long to do, if they can; bad people through a lack of self control; good people, because their hearts are set upon good things. Again, that if a thing was “going to happen,” it has happened; if a man was “going to do something,” he has done it, for it is likely that the intention was carried out. That if one thing has happened which naturally happens before another or with a view to it, the other has happened; for instance, if it has light lightened, it has also thundered; and if an action has been attempted, it has been done. That if one thing has happened which naturally happens after another, or with a view to which that other happens, then that other (that which happens first, or happens with a view to this thing) has also happened; thus, if it has thundered it has lightened, and if an action has been done it has been attempted. Of all these sequences some are inevitable and some merely usual. The arguments for the non-occurrence of anything can obviously be found by considering the opposites of those that have been mentioned.
“How questions of Future Fact should be argued is clear from the same considerations: That a thing will be done if there is both the power and the wish to do it; or if along with the power to do it there is a craving for the result, or anger, or calculation, prompting it. That the thing will be done, in these cases, if the man is actually setting about it, or even if he means to do it later—for usually what we mean to do happens rather than what we do not mean to do. That a thing will happen if another thing which naturally happens before it has already happened; thus, if it is clouding over, it is likely to rain. That is the means to an end have occurred, then the end is likely to occur; thus, if there is a foundation, there will be house.”
Rhetoric. Book Two. Chapter 19.