Donald Trump has taken a strange turn lately. O.K., he has taken a lot of strange turns — that’s what happens when you nominate a short-attention-span candidate who knows nothing about policy and refuses to sit still for more than three minutes. But never mind what passes for Trumpian policy ideas. What’s odd is the shift in what the problem is supposed to be.

When the Trump campaign started, it was, at least nominally, about economics. Foreigners are stealing your jobs, the candidate declared, both through unfair trade and by coming here as immigrants. And he would make America great again with punitive tariffs and mass deportations.

But the story changed at the Republican convention. There was remarkably little economic discussion on display; there wasn’t even much economic demagogy. Instead, the focus was all on law and order, on saving the nation from what the candidate described as a terrifying crime wave.

That theme has continued in recent weeks, with Mr. Trump’s “outreach” to minority voters. His notion of a pitch to these voters is to tell them how horrible their lives are, that they are facing “crime at levels that nobody has seen.” Even “war zones,” he says, are “safer than living in some of our inner cities.”