Keeping up with the latest of the Cool Hour series, Eamonn McDonagh posts another comment on Sam Fleischacker's arguments:
If there was no generally applied principle of self-determination functioning in international affairs at the time [of the Balfour Declaration], and there wouldn't be one for decades to come, then the Palestinians could scarcely appeal to it. Of course, this argument cuts both ways, if there was no such generally applicable principle available for the Palestinians to appeal to at the time then there can't have been one for the Jews either. None of this means that Jews and Palestinians don't have the right to self-determination now.
Putting in my own sixpenceworth for once: I'm not so sure about this. Whether or not there was a 'generally applied principle of self-determination functioning in international affairs' at the time, the principle itself was already perfectly well known. Anyone, therefore, could have appealed to it.