A major plank of the conservative agenda these days is so-called "Right to Work" laws, something Scott Walker recently passed in Wisconsin. Such a law makes it illegal for an employer and a union to enter into a contract ensuring any new employee will be automatically enrolled in the union or its dues program. Conservatives often insist that this is neither a pro- nor an anti-labor position, but merely a question of individual liberty and economic growth. Unions are okay, they say, but justice requires that people not be "coerced" into joining a union just to get a job, which hurts workers' incomes by choking off growth.
This is a crock.
For the moment, let's toss aside the "unions are okay" rhetoric (obvious BS) and temporarily put on ice the "justice" logic (also BS), to focus on the dollars and cents argument. If you're an average worker who just wants to make more money, should you oppose "Right to Work" statutes? Absolutely.
Any murkiness around this central question comes down to a key data problem: When you compare states, there's a whole bunch of confounding factors that can be jiggered to make the numbers turn out one way or another. Conservatives assert that when you control properly, states with "Right to Work" laws have greater income growth, while others, like my colleague Jeff Spross, point to a lot of contrary evidence.
Naturally, I tend to believe the latter numbers more, but there's an even better way of looking at the question. Unions are already nearly dead in most of the country, and "Right to Work" is basically just stacking a couple bricks on the corpse in case Jesus happens by. But if you look at unions as a whole, especially historically, the benefits for workers are obvious and undeniable.
Evan Soltas worked up a clever way of investigating this question when it comes to the Great Compression, the huge decline in inequality during the New Deal era (which necessarily involved large increases in worker pay). As I've written before, the National Industrial Recovery Act contained sweeping pro-labor sections, and led directly to a huge surge in union organizing.
A big part of the Great Compression, shown in historical data, was the decline of the wage gap between skilled and unskilled labor, meaning unskilled labor was being paid relatively more as the New Deal era progressed. Some economists argue that this was due to a greater demand for unskilled labor (and thus higher wages), while others point to NIRA-enabled unions and wage controls during the war restricting skilled compensation.
Soltas looks at the hours worked by both groups to resolve this question. If unskilled workers were in greater demand, then they should also be getting more hours. But if they are getting more pay as a result of union contracts, then managers should respond by trying to give them fewer hours relative to skilled workers. Which happened? Right after the passage of NIRA, "skilled workers' hours rose 10 percentage points relative to unskilled workers' hours." Here's his chart:

It's strong evidence that unions were a key factor in the great decline in American inequality from 1933-1950. On the other hand, since unions began to slide to their pre-New Deal levels in the 70s, median wages have stagnated. Since the entire point of unions is to get more wages and secure employment for workers, this isn't so surprising. It's also not a coincidence that corporations like Walmart furiously despise unions and will move heaven and earth to prevent them from getting established. Higher wages mean lower profits and executive compensation.
This brings me to the liberty and justice angle voiced by "Right to Work" proponents. Most of the objections about the "coercion" of closed-shop union contracts also apply to the publicly traded corporation. As Matt Bruenig writes, a corporation is a kind of capital union, with shareholders its members. Corporate management often spends a great deal of money earned through this capital union on various lobbying and campaign contributions (as labor unions do), forcing shareholders to support that political spending without their consent. Therefore, to protect individual rights against coercion, we must immediately pass a "Right to Own" bill which would require management to get individual shareholders to opt in to any political spending.
Does Scott Walker support such a law? Of course not, the very idea is ludicrous. The reason why is obvious: Because then it would be harder for the wealthy to coordinate their control over the corporate surplus.
Who gets that surplus is really at the root of the disagreement here. Those who think workers should get it support pro-union measures like the National Labor Relations Act. Those who think management and shareholders should get it support anti-union measures like "Right to Work" — or, as it should be defined, The Contract Subversion Law.