Question

In the Talmudic passage in Kiddushin it is brought that according to Beit Hillel, regarding betrothal through intercourse: “These are the witnesses of seclusion, these are the witnesses of intercourse.”
That is: when a couple becomes betrothed through intercourse, there is no need for the witnesses actually to watch the act itself, since they can testify to seclusion that proves—because he is intimate with her—that intercourse took place.
Among the medieval authorities (Rishonim) there is a dispute about what the law is regarding betrothal by money. Can witnesses who did not actually see the giving of the ring testify? Is she betrothed?
Mordechai: She is betrothed, as can be learned from betrothal through intercourse.
Rashba (and this is also the position taken by the Rema, and so ruled in Jewish law): she is not betrothed. Their reasoning: specifically in the case of intercourse it is impossible to see “the brush entering the tube,” whereas in ring betrothal it is possible, so such a “failure,” where the witnesses did not see the giving, does not make for valid testimony that she is betrothed.
It seems that according to Rashba and the Rema, the idea in testimony is that drawing conclusions from compelling circumstances is not enough, since one cannot be 100% certain that the act occurred.
Even though they saw the groom holding a ring, and a moment later the ring appeared on the bride’s finger! (By the way, according to the Chatam Sofer, in such a case even Rashba would agree that she is betrothed, and what he is stringent about is hearsay testimony. However, the Rema, and current halakhic rulings as well, understood the matter in its plain sense—that she must be betrothed again.)
As I understand it, anyone exposed to David Hume’s “problem of causality,” and who accepts it in principle, would raise a criticism of Rashba’s claim.
Rashba’s stringent criterion—not to infer conclusions from compelling circumstances, but actually to “observe” the act—is impossible according to Hume’s problem of causality.
It seems this could serve as a strong argument for those who disagree: Rashba’s requirement is to “observe” the events themselves. But in practice, you are not really observing them! Meaning: according to your approach, it is not enough to see: groom, ring, bride, ring. Rather, what is required is: groom, ring, giving!, bride, ring.
But the “giving” you are talking about also is not something that is read directly, but only through drawing a circumstantial cognitive inference (according to Hume). And since it is never actually possible to observe acts and circumstances themselves as they occur, the only way to formulate it is that Jewish law is satisfied with using “mental completions” in everything connected to testimony.
 
Do you think that on this basis the halakhic ruling, when tested by Hume, ought to be different?