No matter how acrimonious the Republican primaries get, all of the candidates agree on one thing: Barack Obama must be defeated in November 2012. For 3 of the 4 remaining candidates, that is virtually the only important issue in the Republican primary race. Obama must be defeated and the only issue to resolve in the primaries is who has the best chance of doing so. Only Ron Paul asks the questions that should follow logically: Why is it so important to defeat Obama and what will you do differently from him?

In response, most of the Republicans offer only platitudes. “Obama believes in taking from one person and giving to another. He wants to turn the United States into a European social democracy with a massive welfare state, etc.” I happen to agree on these points with one caveat – the United States already is a European-style social democracy. That boat sailed many decades ago. With a welfare state measured in trillions that dwarfs the entire economies of most nations of the world, the United States is a poster child for social democracy and is now listed 10th on the Index of Economic Freedom.

However, assuming that Barack Obama is supportive of this and the Republican candidates are not, there must be fundamental philosophical differences between them and Obama that would translate into tangible policy differences. However, if one listens closely to what they actually say, none of the Republican candidates actually disagrees with Obama in principle on any single issue or identifies a specific power of the presidency that they would exercise differently – except for Ron Paul.

If Obama really is uniquely terrible as a president, there must be actual things he has done that make him worse than previous presidents. During the 2010 elections, the Tea Party movement focused on Obamacare. The Tea Party-fueled 912 Project was able to draw hundreds of thousands of people to Washington to protest this one program. Yet, with Medicare and Medicaid alone accounting for 1/3 of all healthcare spending in the United States and total government spending likely accounting for over half, why was Obamacare such a fundamental change? Measured in terms of dollars, Obamacare was rather insignificant as an increase in government involvement in healthcare. If government-provided healthcare is really bad in principle, then opponents of it should object to all of the programs, especially Medicare, which costs about 6 times as much as Obamacare. But they don’t – except for Ron Paul, who has a clearly defined and funded plan to let workers entering the workforce opt out of Medicare.

Of course, there is one aspect of Obamacare that is different in principle and that is the individual mandate. Tea Partiers have made many eloquent speeches about how antithetical to freedom this central plank of Obamacare is. Again, I agree, but do the Republican candidates for president? Romney certainly doesn’t. Romney’s Massachussetts plan that inspired Obamacare is also centered around an individual mandate. Romney openly defends the principle to this day. His problem with Obamacare? That it is administered by the federal government and forced upon all 50 states. While his support for federalism might be admirable, Romney does not recognize any individual right not to be forced to purchase government-approved health insurance. If the state government imposes that obligation, Romney has no objection.

Gingrich doesn’t even object to an individual mandate at the federal level. While Santorum does seem to oppose this aspect of Obamacare, he has already voted for the prescription drug program, which expanded Medicare by as much in dollars as Obamacare costs in total. There is only one candidate that makes any argument or has any tangible plan to get the government out of the healthcare business completely – Ron Paul.

The same can be said for government spending in general. Yes, all of the Republican candidates rail against excessive spending, deficits, and debt. They decry Obama’s unholy deficits and say that they will cut spending and push for a balanced budget amendment to the U.S. Constitution. That’s all fine, but what exactly are they going to cut? This is where those striking differences from Obama start to dissipate. None of the candidates will actually name programs that they will cut beyond infinitesimally small ones like the National Endowment for the Arts – except for Ron Paul. Paul has already published the first budget that he will submit to Congress and it cuts $1 trillion during his first year as president.

This budget not only saves money but indicates the philosophical difference between Ron Paul and the rest of the candidates. By actually assigning funding of zero to the Departments of Education, Commerce, Energy, Housing and Urban Development, and the Interior, Paul makes two philosophical statements that the other candidates do not. The first is that the government should have no role whatsoever in the areas that these departments regulate. They represent areas of life that should be left to voluntary cooperation between free people, not coercive mandates from the government.

The second is that Paul recognizes that these are functions that the government has no legitimate authority to tax individuals to fund. For the rest of the candidates, there is nothing that the government cannot tax people for, as long as it fits in with their plan. They may suggest cutting unsubstantial amounts here or there, but none of them cuts these functions to zero. They all believe that individuals can be taxed to fund government regulation and/or subsidization of all areas of human activity – except for Ron Paul.

All of this is rooted in a fundamental difference between Ron Paul and any other candidate for president in 2012, Republican or Democrat. It concerns the role of government. Only Ron Paul actually uses the words “role of government” in speeches or debates. Why? Because only Ron Paul believes that the role of government in society is limited. You will hear the other Republicans use the terms “small government” or “smaller government,” but rarely, if ever, will you hear them say “limited government.” On this principle, there is no difference at all between Obama, Gingrich, Romney, or Santorum. Santorum has actually said this explicitly (about the 1:20 mark), while the others demonstrate it through their positions on the various issues. Only Ron Paul argues that there are limits on the power of the government. The rest merely argue about how that power should be exercised.

This concept of limited government is so absent from modern American political discourse that it is necessary to define it. If Americans still truly believe that certain rights are inalienable, then there are certain things that the government is simply not allowed to do, not even with the support of a majority vote. In other words, those inalienable rights cannot be voted away, because they do not belong to the majority. They belong to each individual. That is limited government. Only Ron Paul defends it.

Nothing illustrates this better than Ron Paul’s position on what is supposed to be the fundamental principle around which American society is organized, liberty. Ron Paul defends liberty unconditionally while his Republican opponents openly attack it, just as Obama does. Many of them use the term “individual liberty,” but once it comes to specifics they are in lockstep with Obama.

Liberty has a definition and it is not “the ability to do whatever you want.” There is a natural limit to liberty that precedes the government. It is not created by the government. The natural limit of liberty is the equal rights of others. In other words, an individual has the right to do whatever he pleases as long as he does not invade the person, liberty, or justly acquired possessions of others.

This means that the individual might do things that others don’t approve of, like use drugs, watch pornography, or practice a religion that is antithetical to their own. Others are free to disapprove of these activities, but they are not justified in using violence against the people who engage in them – and all laws are backed by the threat of violence. In fact, since these activities do not invade the person, liberty, or property of another person, individuals have an inalienable right to engage in them. Governments at all levels should be powerless to prohibit them. That is, if the society really is organized around liberty. “No man has a natural right to commit aggression against the equal rights of others ,and that is all from which the law ought to restrain him.” That was how the author of the Declaration of Independence defined liberty. You either agree with him or you don’t. There is no middle ground.

At the federal level, the defense of liberty is defined by the first 10 amendments of the U.S. Constitution, popularly called the Bill of Rights. If there is anything of substance that makes America freer – in the real world – than the average banana republic, it is these limits on government power. Yet even on these most basic principles, only Ron Paul takes a stand for liberty. The other Republican candidates agree with Obama that these protections can be sacrificed in the name of security.

Romney stated that he would have signed the NDAA bill which granted the government the power to detain U.S. citizens without due process. In explaining his position, Romney made the ludicrous, counterintuitive argument that Americans have a right to due process unless they commit acts of terrorism. Excuse me, Mitt, due process is the means by which we determine if the suspect committed the crime or not. That is the whole reason for due process – to determine guilt or innocence. Romney doesn’t undestand that or doesn’t care. This should horrify any lucid American.

Newt Gingrich made this same argument in a previous debate in defending the Patriot Act. In fact, he thinks that the powers granted to the federal government in that law should be expanded. Rick Santorum doesn’t substantively disagree. Make no mistake, these are not fine points of law that are being argued here. They are the fundamental constitutional principles that define America as a free country. They are under all-out assault by both the Obama Administration and every Republican presidential candidate except for Ron Paul. That the other candidates get loud cheers in debates when arguing to abolish these constitutional protections of liberty should send a shiver up the spine of every American. Recall the words of the Star Wars character, “So this is how liberty dies, with thunderous applause.” Without exaggerating, it has come to that.

Americans do have a choice in this election, but it is not between Obama and one of the other Republicans. There is no substantive difference there. The true choice is between Ron Paul and unlimited government, which is government under Obama, Romney, Gingrich, or Santorum. That means a government that can tax you for anything it wishes to, can detain and search you without warrant or probable cause, and can send soldiers to arrest you and imprison you indefinitely without legal representation, a hearing, or a trial. It is a government whose power knows no limits, that can forcefully control every area of your life and force you to pay for its domination of the entire globe. Whatever happens in the years ahead, Americans cannot say that they did not have an opportunity to choose liberty over tyranny. This may be their last chance.

Tom Mullen is the author of A Return to Common Sense: Reawakening Liberty in the Inhabitants of America.