There's an old saying that in a negotiation, he who cares least wins.

That is, as far as I can tell, Donald Trump's strategy on immigration. He has promised all manner of improbable outcomes — like that Mexico will pay to build a wall that only America wants, or that unauthorized immigrants will leave without America having to conduct mass deportations.

It all seems like fantasy. But when you read Trump's immigration plan closely, you realize Trump actually has a theory of how to get this done — it's just a very, very cruel one.

Trump's plan is to inflict tremendous pain on vulnerable people who have, in most cases, done nothing wrong. In some instances, he wants to inflict that pain in order to make another, more powerful actor do something he wants. In some cases, he seems to want to inflict that pain for no particular reason at all. But his plan, read in its totality, is breathtaking in its callousness.

If you understand immigration policy as a kind of negotiation between the United States government, legal immigrants, and unauthorized immigrants — which is clearly how Trump understands it — his plan is to win the negotiation by being willing to inflict more suffering than the other actors can bear; he is willing to care least about the human cost of the negotiation.

The plan would be a disaster for immigrants if enacted. But even if it's not enacted, the plan is a disaster for the Republican Party, which is somehow going to need to co-opt Trump's appeal to anti-immigration voters, but absolutely cannot afford to be associated, in the minds of Hispanic voters, with this document.

(Quick note: For a more complete description of Trump's immigration plan, read Dara Lind's excellent guide. In this piece, I focus on the plan's more morally shocking aspects.)

Trump's affection for collective punishment

Take the wall. Trump keeps saying he'll make the Mexican government pay for the wall. But as Dara Lind notes, Trump isn't proposing to make the Mexican government pay for the wall. He's proposing to make Mexican people pay for the wall.

Trump's idea is to confiscate the money unauthorized immigrants send to their (extremely, extremely poor) relatives back home, increase fees on a visa program NAFTA created for (legal) Mexican workers, increase fees on the border crossing cards used by Mexicans who (legally) cross in and out of the United States to work, increase fees on all temporary visas issued to Mexican CEOs and diplomats, and increase fees on ports of entry to the United States from Mexico.

In other words, Trump has no actual mechanism to make the Mexican government build a wall across the border. But his plan, such as it exists, is to inflict so much pain on Mexican people who need to cross the border legally, and on poor communities that depend on remittances from relatives in the United States, that the Mexican government buckles and builds the wall. Or maybe the plan isn't to have them build the wall, but to simply raise revenue under the guise of trying to pressure Mexico to build the wall.

What's important to understand about this plan, though, is that it's fundamentally an act of collective punishment. Most of these ideas punish legal immigrants for the actions of people coming here illegally.

For all Trump's rhetoric about loving legal immigrants, he intends to either hold them responsible for illegal immigration or hold them hostage in his fight against illegal immigration.

And that speaks to a fundamental theory that comes clear in Trump's proposal: He doesn't see unauthorized immigration as something done by individual immigrants but as something done by Mexicans more generally, and something that all Mexicans — and their government — can be held accountable for.

Targeting the children and families of unauthorized immigrants

When Mitt Romney embraced "self-deportation" in 2012, it was considered an awful mistake.

"It's a horrific comment to make," Republican National Committee Chair Reince Priebus later said. "It's not something that has anything to do with our party. But when a candidate makes those comments, obviously it hurts us."

But self-deportation is Trump's plan, too. And Trump's insight here is that the best way to drive unauthorized immigrants out of the country isn't to target them. It's to target their children and families.

He would, for instance, ban unauthorized immigrants from receiving tax credits meant to help their children — children who are, remember, US citizens. But Trump would try to get around that problem by unwinding birthright citizenship, though he doesn't say whether he wants to amend the Constitution or simply appoint different Supreme Court justices.

Meanwhile, he also promises to confiscate the money unauthorized immigrants send home to their families — though, as Lind observes, Trump's proposal says these remittances total $22 billion, which is actually the combined amount of money sent home by all emigrants from Mexico, whether legal or illegal, and regardless of whether they went to the United States or Spain or Canada or wherever. Perhaps more importantly, Trump offers no details on how he would distinguish remittances sent by legal immigrants and unauthorized immigrants.

But the plan, for all its holes, is clear in its intent: Drive unauthorized immigrants out of the country by impoverishing their children who live here and their families back home. It is, again, a form of collective punishment, and it visits its harshest sanctions on those who have done the least wrong.

Do not give us your tired, your poor, your huddled masses yearning to breathe free

The most unexpected part of Trump's immigration plan is his crackdown on refugees and asylum seekers. He does three things that would make it exceptionally hard to find relief from oppression in the United States.

First, he wants any immigrant who gets into the country without papers — which is necessarily how refugees and asylum seekers arrive — detained from the moment they arrive to the moment they are deported. The problem for asylum seekers is that would make it almost impossible to find a lawyer to build their case. But as Lind says, that probably won't matter all that much, "because most of them probably wouldn't be eligible for asylum under the Trump administration anyway."

Which brings us to Trump's second initiative, which is to "increase standards for the admission of refugees and asylum-seekers to crack down on abuses."

Trump doesn't say what this means, but it's a safe bet that the new standards will be pretty tough to meet. After all, the current standards are already pretty tough to meet — the mere fact, for instance, that you are marked for death in your home country is not always enough to qualify.

Finally, Trump wants to require applicants for entry into the US "to certify that they can pay for their own housing, healthcare and other needs." But many refugees and asylum seekers — particularly those leaving refugee camps, or fleeing oppression that has already taken their homes and savings — can't support themselves immediately upon entry into the United States. Under Trump's rules, that would make them ineligible for entry.

Here, too, the logic of collective punishment dominates. Trump is taking a series of proposals meant to deter a specific kind of economically driven unauthorized immigration and applying them to people fleeing oppression and forced displacement.

The dark core of Trumpism

It's easy to treat Trump as a joke at worst, or a curiosity at best. His rise has been a wonderfully fun story, and a useful way to explore some unusual facets of the Republican electorate's psychology. But even despite his sustained lead in the polls, few pundits give Trump any chance at all of winning the Republican nomination, and even fewer feel the need to take his policies seriously.

But even if you don't think Trump has a chance in hell of winning the Republican nomination — and I am not precisely sure how much longer that position will be tenable for — he's running a campaign that will, inevitably, put pressure on the other candidates.

Right now, every single Republican candidate for president is holding daily meetings with their top strategists to develop plans for winning over Trump's voters and, eventually, winning over Trump so he doesn't mount a third-party candidacy.

None of the candidates will be able to match his bluster, his bravado, or his magnetism — and they know it. So they'll have to appeal to Trump's voters without actually being Trump. And the most obvious option is to match his substance. Already, Scott Walker is bragging that his immigration plan is "very similar" to Trump's.

But Trump's immigration plan is deeply cruel. It punishes legal immigrants for the actions of unauthorized immigrants, children for the actions of parents, and refugees from oppression for the actions of refugees from poverty. It's a plan based on the logic of collective punishment and a willingness to care least for the lives of immigrants.

If the Republican Party decides it needs to adopt some of Trump's ideas to survive, it will be a dangerous turn on two levels. It will be a disaster for immigrants, who need more sensible and humane policies, and it will be a disaster for the GOP, which needs to appeal to an increasingly Hispanic electorate.

VIDEO: Donald Trump on immigration