Of course an opinion can be useful without being falsifiable. “Human life as we see it is not utterly worthless and meaningless,” is probably not falsifiable (how would you falsify it?), but believing it is very useful for avoiding suicide and the like.
Opinions are not falsifiable by their nature (well, maybe by revealed preferences). But, hopefully, core approaches to the study of history (e.g. “great people” vs “impersonal forces”) are more than mere opinions.
Of course an opinion can be useful without being falsifiable. “Human life as we see it is not utterly worthless and meaningless,” is probably not falsifiable (how would you falsify it?), but believing it is very useful for avoiding suicide and the like.
Opinions are not falsifiable by their nature (well, maybe by revealed preferences). But, hopefully, core approaches to the study of history (e.g. “great people” vs “impersonal forces”) are more than mere opinions.