You may feel strongly about a particular public policy issue. What happens when you find yourself opposed by members of the political party who should be your ideological kin? You might feel betrayed. Maybe even enough to conclude that these dissenters must have been corrupted by the system—and that political institutions are the real source of obstruction.

Legislation proposed this week by Senators Joe Manchin (D.-W.V.) and Pat Toomey (R.-Pa.) to strengthen background checks on gun purchases may be a reasonable measure. But opposition from senators who some call "Red State Democrats"—from small states like North Dakota, Montana, Wymoming and Alaska—may hold up the Toomey-Manchin bill. The New Republic's Alec MacGillis is upset with these turncoats. He's also concluded that the upper chamber is not only broken-down: apparently its design was flawed from the very beginning.

MacGillis, recalling a tense exchange in which he provoked former North Dakota Senator Kent Conrad, argues that giving each state equal representation in the Senate was in fact a "not-so-Great Compromise." Constitutional originalists, he says, ignore the fact that James Madison argued for the "Virginia plan," in which larger states would have been given more representation in the upper house.

But even if he can beat the originalists at their own game, MacGillis doesn't tell us what he would prefer to the current arrangements. An upper chamber in which larger states have more votes might require a dramatic expansion of the number of seats. As MacGillis points out, the population disparity "between California and Wyoming is now 66 to 1." What would be a fair allocation of seats?

Dramatically expanding the size of the Senate would surely dampen its ability to foster the kind of collegiality that brought about the bipartisan Toomey-Machin bill in the first place. The ability to deliberate productively (even if not evident today in the way it was in previous eras) would also be hampered by too many members.

One workaround might allow individual senators more votes—as if they owned more shares in a corporation—but this would wreck comity as well. Would California senators be given more time to speak than their Wyoming counterparts?

The individual power of senators is also derived from the body's relatively small size—with more members, who will care if one senator speaks up against the president? The current system, while not always enabling quick passage of legislation, keeps one branch from wielding too much power. That principle is the genius of 1787, whether or not the way it was implemented aligns with all of today's democratic impulses.

Despite worrying expansions of executive power in foreign affairs in recent decades, in domestic affairs the administration's agenda is still limited by Congress. Presidents must occasionally wish for the power of a prime minister: to enact new legislation, simply schedule a vote, whip one's party colleagues—and voila, progress.

The United States does not have a parliamentary system. And if it did, President Obama might not be in office today, at least not under the current allocation of Congressional districts.

One can imagine a revolution in which the 1787 principle of checks and balances is junked in favor of what might be a more efficient (but potentially tyrannical) system. But even with an issue as heart wrenching as guns, Americans don't seem ready to hit the barricades yet.