Thank you very much.
And one more thing:
From reading parts of your books on deontic logic in light of Jewish law (mainly the first one, and a bit from the book on conflicts), I didn't find that you dealt directly with Williams's aggregation. (If A is obligatory and B is obligatory, then [A and B] is obligatory. And one can also think about the reverse direction.) Am I right?
Have you dealt with this principle elsewhere?
(Of course this is also connected to the matter of one prohibition not taking effect on another prohibition. I have a feeling that the halakhic discussion contains interesting mereological considerations: a more inclusive prohibition, an additional prohibition, simultaneous application, and many discussions invited by each of these categories.)

I don't recall. The other direction seems clear to me (if a and b, then each one of them individually). As for the first, in my opinion there are objections. It's worth looking at the various objections in deontic logic and the halakhic solutions in our book.

I doubt that you can fit the topics of one prohibition not taking effect on another prohibition, and of inclusive and additional prohibitions, into deontic logic. That assumes these laws are a logical result and not a special rule in Jewish law. I don't think you're right. For example, according to that, a normative system in which one prohibition does take effect on another prohibition, or does not take effect even in cases of additional or inclusive prohibition, would be inconsistent. I'm almost sure that's not correct.

Hello again,
You write: "I doubt that you can fit the topics of one prohibition not taking effect on another prohibition, and of inclusive and additional prohibitions, into deontic logic. That assumes these laws are a logical result and not a special rule in Jewish law. I don't think you're right. For example, according to that, a normative system in which one prohibition does take effect on another prohibition, or does not take effect even in cases of additional or inclusive prohibition, would be inconsistent. I'm almost sure that's not correct."
I don't see how you reached the conclusion that these principles, according to my initial thoughts on the subject, are a "logical result." Even aggregation in the ethical context is not a logical result, unless you assume modal semantics—without the pluralism of operators that you propose in the book—and then even in the weakest system of modal logic (K), you get both directions as theorems.

I'm actually going in the opposite direction: under the assumption that this is the principle (one prohibition does not take effect on another prohibition, and what follows from it…), what logic and semantics would suit the description of the system? And here, logic is only a tool. What ultimately interests me is the metaphysics/ontology of norms (halakhic and others), not the logic.
By the way, it may be that what I need here is non-monotonic logic that would allow one obligation to change the inferential force of another obligation. I don't know. I'm only beginning to think about it.
And another aside: rejecting aggregation in both directions is not unique to Jewish law. Of course there may be differences in the details, but as you surely know, in the ethical context there are those who reject it too. I'll go back and look at the book. I don't remember you addressing aggregation there. I'll look again.

I don't know what aggregation is. I was responding to what you wrote in connection with that concept.
I definitely assume modal semantics. As far as I understand (though I'm far from being an expert), without it deontic logic has no sharp meaning.
If you're looking for a deontic formalization of the halakhic assumptions, that's something else. But I'm not sure it would be of any use. Formalization for the sake of formalization has little value. I was talking about using the existing logic and explaining the halakhic principles through it.

Hello Y.,
I saw in your words that you point to studies that have been done regarding the topic of one prohibition taking effect on another prohibition. I would be grateful if you could direct me to them more precisely, since I am interested in writing a research paper on this topic (less on the philosophical side and more on the attitude toward this concept in the generations of the Tannaim).
Thank you very much.