Things Aristotle calls “probable” have nothing to with statistics. The legal notion of “probable” cause is much closer to Aristotle’s concept of probability. It refers to conclusions for which there are good reasons, but which are not expected to be established beyond reasonable doubt.
Mathematics achieves certainty and rigorous necessity through the artifice of abstracting away real-world complication and ambiguity. Whenever we are concerned with the real world as we actually experience it, whatever conclusions we reach at best follow probably rather than necessarily.
Keeping in mind the probable character of judgment in general should not prevent us from acting decisively. This kind of “probability” is all the basis we need to have well-founded practical confidence. We can have strong confidence without false pretenses of certainty.
To claim certain knowledge in these cases amounts to what Kant called dogmatism. The deep roots of American pragmatist philosophy have more to do with something like an Aristotelian emphasis on the practical sufficiency of probable judgments than with later reductive, utilitarian theories of value. (See also Aristotelian Dialectic; Dialectic Bootstraps Itself; The Epistemic Modesty of Plato and Aristotle; Demonstrative “Science”?; Kantian Discipline; Copernican.)