The Louisiana Purchase, most fortunate land deal in American history, was to Thomas Jefferson's critics a case of unconstitutional overreach. ( St. Louis Public Library )

Every big peacetime project that any democracy has ever undertaken has generated controversy.

In retrospect, both the Louisiana Purchase of 1803 and the Alaska Purchase of 1867 look like Heaven-sent, near-theft, no-brainer, "where would we possibly be without them?" steps in the development of American scale and might. But each met bitter opposition in its time.

In 2014, it is difficult to imagine the San Francisco Bay area without the Golden Gate bridge. But in 1930, the proposed bridge was mocked as an unnecessary eyesore and resisted by figures as august as Ansel Adams (who later admitted it was not so bad). Congested as today's Bay Area traffic is, it would be incomparably worse without the BART subway/rail system. Fifty years ago, voters and politicians decided to go ahead with construction by very thin margins.

The Civil Rights Act of 1964—a "big project," though not of the infrastructure variety—passed only after the Senate broke a prolonged Southern filibuster. (They were "real" filibusters in those days.) Medicare is now the sacred cow of American politics. Before the vote to approve it in 1965, it was opposed even more fervently than was Obamacare, as the fateful first step toward "socialized medicine." In the summer of 1941, when the Nazis had taken over much of Europe and the attack on Pearl Harbor was just months away, the House of Representatives approved a military draft by a single vote.

Obviously this history does not mean that just because a plan is divisive or unpopular, it will necessarily turn out to be a good idea. But it illustrates two instructive realities.

• The first, which is plain fact, is that big choices are rarely easy choices. Precisely because of their scale and impact, they involve tradeoffs, imperfections, pros and cons.

• The second, which is my opinion, is that big infrastructure investments are usually under-valued and over-criticized while in the planning stage. It's much easier to envision the here-and-now costs and inconveniences, and harder to imagine fully the eventual benefits. That's not true of all of them, but it's how I read the preponderance of American-history evidence from the Louisiana Purchase onward.

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With that context, let's go back to California's ambitious and thus naturally controversial plan to build a north-south high-speed rail system. In the previous installment, I gave the basic pro-HSR case.

For today, a survey of the opposition, which I will lay out as fairly as I can, saving responses for an upcoming post. Here's why I'm happy to do so:

Even the most stalwart supporter of the original Medicare plan, or today's Obamacare, had to know that there were uncertainties and drawbacks. Big decisions are more often 55-45 than 90-10. You have to weight the pros and cons, the knowns and unknowns. I think the pros still prevail in this case, but we have to look at the cons.

The main claims are:

• A high-speed rail system might be great in theory, but the realities of this plan fall far short.

• It will cost too much, take too long, use up too much land, go to the wrong places, and in the end won't be fast or convenient enough to do that much good anyway. And, from some people,

• It's an old-tech band-aid to a problem that really calls for a "disruptive"-tech fundamental solution, from self-driving cars to the Elon Musk-style hyperloop.

You can see a lot of the objections in one place in a dispatch conveniently titled "7 Ways James Fallows is Wrong About the CA Bullet Train." Also see this from RealClearPolitics on the deteriorating politics of the HSR plan within California.