After writing on the meaning of "conservatism," a friend suggested that I take a shot at defining "liberalism." The truth is that I haven't really given modern liberalism much thought. We put so much stock in these words that describe our political perspectives, but most of us almost never think about what the other side believes. "Liberal" is much more than a mere label for anything conservatives politically oppose.

Conservatives and modern liberals actually share classical liberal ideology as a common ancestor. That's where we derive our focus on civil liberties, adherence to the rule of law and an open economy. Like our classical forerunners, most American liberals believe that government's purpose is to protect our rights of life, liberty and the pursuit of happiness from both government oppression and each other.

But liberals immediately diverge from their conservative brethren with the view that government can and should improve civic equality and actively enhance the lives of Americans.

Perhaps President Franklin Delano Roosevelt best captured a liberal's view of government. "Government has the definite duty to use all its power and resources to meet new social problems with new social controls," Roosevelt wrote, "to ensure to the average person the right to his own economic and political life, liberty, and the pursuit of happiness."

Since America's founding, liberty and equality have existed in a necessary tension. Prioritization of liberty and equality greatly shapes our ideological alignment.

Free people are rarely equal, and equal people are rarely free. Liberty allows for tremendous diversity and differentiation, but it doesn't provide any basic guarantees about quality of life. As a nation, we've decided that some basic minimum protections are important to us. Our social safety nets protect vulnerable Americans from abject poverty and easily preventable or curable health conditions. We also craft laws to regulate public resources and protect the environment.

The tradeoff for those government programs and laws is burdening other Americans with taxes to pay for them and imposing restrictions on the conduct of individuals and businesses.

In close cases, liberals regularly tip the public policy scales in favor of equality over liberty.

Modern liberals aren't particularly concerned about the size of government because they believe it ought to be large enough to serve as a social and economic counterweight to the private sector.

In spite of conservative assertions to the contrary, support for a more robust government doesn't mean most liberals are against economic success. They simply believe that the relative burden they impose on the top end of the economic spectrum is light compared to the benefits that government creates for the bottom end.

Liberals don't carry some bizarre love of politicians or necessarily believe that bureaucratic solutions are ideal. Their comfort with government action is a matter of genuine empathy applied to problems facing millions of people. The level of coordination and planning necessary to address challenges of such size and scope means that government is often the most readily identifiable vehicle for solutions.

Unfortunately, a government with that kind of power is also a tempting tool for societal control.

A strain of liberalism is emerging in America that's more aligned with Thomas Hobbes's idea of a powerful governing monarch than the virtues that shaped our republic.

Most modern liberals aren't advocating for an absolute sovereign per se. However, many do support macroeconomic planning, centralization of government power, and government-imposed social restraints.

In shaping the economy, liberalism renders a value judgment that the economy should be more equal and just than market forces naturally produce. Liberals use government policymaking to theoretically force economic disparity towards a more robust middle class. Rather than nationalizing America's businesses to create the desired economic outcomes, modern liberals use taxation and government spending as equalizing forces.

Modern liberals also seem to struggle with the idea of allowing states to operate as public policy laboratories--opting instead for federal regulations and laws that apply nationwide. For a political ideology that prizes diversity, modern liberalism appears to have little interest in a broad range of governing philosophies and ideas.

When it comes to civil liberties, the extremes of the political right and left share the common sickness of intolerance.

Liberal social morality is every bit as much of a threat to liberty as the theocratic tendencies of many conservatives. Increasing support among so-called liberals for laws restricting private speech, association and even religious liberties are troubling.

Consider government efforts to prohibit or punish "hate speech" as one example. The intention is clearly laudable, but government efforts to regulate speech are corrosive to the First Amendment. To preserve our way of life in America, civil liberties must remain liberal in the classical sense. This demands tolerance of many private views and biases that may fall well outside of our mainstream culture.

Perhaps, the greatest conceit of the modern liberal is the belief that American government is more just and equitable than the sum of its constituents acting individually. That ideological folly is only equaled by conservatives who fancy individuals and corporations as far more just and equitable than they actually are.

Debate and civil discourse help us feel out the equilibrium between liberty and equality even if imperfectly. Our representative democracy provides the mechanism for us to correct our national trajectory when we lose ideological balance in either direction. There's nothing magical about our conservative or liberal identities that renders either the rightful heirs to America's legacy of life, liberty and the pursuit of happiness. If we're willing to acknowledge our shared ideological past, we might find just enough common ground to chart a better path for our future.

Cameron Smith is a regular columnist for AL.com and vice president for the R Street Institute, a think tank in Washington, D.C.