The 2015 mayor's race in Philadelphia is about to shift into full gear. Many voices will warn that free spending in the election will again make Philadelphia a symbol of corruption. Critics may particularly scorn "outside groups" and their independent spending. But Philadelphia needs more money in elections, not less.

Philadelphia, like many other cities and states, limits campaign contributions. Such limits are said to prevent corruption, the exchange of favors from officials for contributions. Those who abide by such limits are "inside" the system of regulation.

But not everyone active in a campaign need be an insider. Some groups do not contribute to candidates or parties. Instead they raise and spend money directly on speech, in the hopes of persuading voters.

Such spending exchanges nothing with candidates and thus cannot corrupt officials. Like other speech, it is protected by the First Amendment. After all, prohibiting such spending would prohibit the freedom to say "Vote for Candidate X" or "Vote against Candidate Y."

Such spending and speech is not just a First Amendment right. It is also a good thing for the republic. Let me elaborate.

Independent spending often means more spending overall during an election. Isn't that undesirable? To the contrary, political scientists have found that more spending fosters better-informed voters. Moreover, those who were less informed prior to an election gain more from increased spending than those who were better informed initially.

But we don't have to be content with academic studies. The Philadelphia mayoral contest will show another advantage of independent spending.

Public education often dominates urban elections. Philadelphia voters are hearing a lot about the issue. In part, voters will hear the voices of those who have a stake in the public education status quo. This is neither surprising nor troubling. Teachers, for example, have an interest in their wages and pensions, and no doubt a genuine faith that more spending on public education will solve most of its ills. Like everyone, they have a right to spend on political speech advancing their interests and ideas.

But they don't have right to be the only voices heard.

I am not an expert on public education, but I do know that citizens and parents in many cities think schools should be a lot better. Ideas about changing the status quo need to be heard. Those with an economic stake in the status quo are not likely to advocate significant changes.

Contribution limits complicate challenges to the status quo. Generally it is far easier to raise campaign cash if you are organized, and you are more likely to be organized if you have a concrete stake in an election. Organizing politically requires money and time; it is more likely if an election offers concrete benefits to people who incur such costs. Citizens supporting the status quo will be heard. What about those who want change?

Independent spending allows an end run around the status quo. A few engaged citizens can contribute significant sums to advance alternative policies. The absence of contribution limits and related regulations means such groups do not need extensive political organizations. Such groups are thus less likely to be part of the policy status quo.

Something like this seems to be happening in the Philadelphia mayoral contest. Media reports indicate a group called American Cities will be spending independently to make the case for school choice and for candidates who support that idea.

Citizens will disagree about school choice. But the people of Philadelphia will have a better election if the case for school choice is heard. It seems unlikely that choice would be on the voters' agenda if independent spending were banned. I suspect, given the power of the status quo, that what is true in public education is true of other policy areas.

Philadelphia is a great American city, but it does not suffer from too much political competition. It has seen one close mayoral election in 20 years. Outside groups are fostering competition in ideas and policies. The voters will decide between the received wisdom and new alternatives, and they will be better informed and have more choices thanks to those outsiders and their money.

John Samples is vice president and publisher at the Cato Institute in Washington and author of "The Fallacy of Campaign Finance Reform" (University of Chicago Press).