Anarchy is popularly used as a synonym for chaos, but is this really accurate? At the root of the word "anarchy" are Greek terms that translate to "no rulers," but this does not in turn mean "no rules." The principled anarchist seeks to discover the natural rules that govern humanity rather than impose arbitrary rules upon others. Of course, this doesn't stop wannabe authoritarians from calling themselves "anarchists," and there is heated debate within the anarchist communities over the nature of human nature, but the defining idea remains.
Meanwhile, those who cite "law and order" as a reason to support government deliberately turn a blind eye to the history of governments as agents of chaos. The destruction wrought by dictators, the economic chaos of central planners, the violent black markets that sprout up in the wake of prohibitions, the terror created by police state control, and every other chaotic element we see so plainly in history books and current events are the result of attempts to impose order through government. The order created organically by society occurs in spite of government intervention, not because of it.
Yes, free people may commit heinous acts that violate the rights of others, but government is the only system that has allowed humans to commit mass slaughter on scales that boggle the mind. Even the most outlandish potential risks of freedom are dwarfed by the historical and current reality of war and democide. There is nothing that guarantees chaos as effectively as people who demand governmental power to bring their vision of "order." There is no more powerful force to create order than the decentralized voluntary actions and associations of free people.
See also: Anarchism Versus Mythology