Let the arguments begin.

Avatar” is a phenomenon. “Alice in Wonderland” is a blockbuster and “How to Train Your Dragon” looks like it’s a sure thing.

So all over town folks are debating: Should most movies be in 3D? Which are right for 3D? Will the down-and-dirty conversions from 2D prove effective or will only the “high-end” process pay off? Will the early days of 3D play out cautiously like the start of Technicolor or will the studios quickly take the leap?

There’s a lot at stake in all this, which is why the debates are already getting snarky. Rivals are dismissing “Clash of the Titans” as “Trash of the Titans” since Warner Bros. rushed its “low-end” conversion in an attempt to steal theaters away from “Alice” and “Dragon.” By contrast, Universal opted to stay with a 2D “Robin Hood” despite the urgings of director Ridley Scott.

Scrutinizing the list of upcoming 3D releases, insiders wonder if the genre can survive the flying projectiles of “Jackass 3D” (from Paramount in October) or the emotional dander of “Cats and Dogs: The Revenge of Kitty Galore” (from Warner Bros. in July).

There are economic incentives to jump to 3D, since exhibitors are increasing ticket prices by as much as 26% in some markets. Hence the first

cycle of 3D movies is under pressure to deliver the goods or face audience rebellion.

Studios were wary about the advent of color 50 years ago, confining the process mainly to spectacles and showcases of foreign locales that offered a contrast to TV. But when television went to color in the 1960s, the majors quickly panicked and embraced the technology fully.

Judging from the 3D release schedule, filmmakers are being more aggressive. The 3D agenda in coming months is packed with obvious entries like “Toy Story 3,” “Harry Potter 7” and “Shrek Ever After” but also more chancy entries like “Drive Angry,” “Puss in Boots,” and “The Smurfs.”

Clearly, Disney wants most of its films in 3D, but the company is instantly becoming Hollywood’s answer to Procter & Gamble. Its product may run the risk of becoming a brand in search of a movie.

Jeffrey Katzenberg of DreamWorks Animation believes filmmakers, using the proper tools, will learn that 3D provides “an immersive experience” that amplifies audience feelings. That means shooting in true 3D, not rushing into 11th-hour conversion. Certainly he’s proved that in animation: When the dragon takes flight in “How to Train Your Dragon,” with the boy triumphantly riding atop him, the movie itself starts to soar.

Katzenberg says he would like to have seen “Hurt Locker” in 3D. He feels that film could have been even more stirring in that format.

On the other hand, some believe “Alice” was more effective in 2D than in 3D.

The argument is clearly just starting.

At the risk of sounding stodgy, I’m just grateful that I saw the great films of the past in 2D. A 3D “Easy Rider” would have put me over the edge.

‘Green’ and ‘Greenberg’

The 3D debate parallels that surrounding dramatic films, with the failure of “Green Zone” providing yet another example of a quality movie that shot itself in the foot trying to be a blockbuster rather than a tightly budgeted thriller carrying less-expansive expectations.

Green Zone,” a stirring movie about Iraq, was shot like a $100 million “Bourne” sequel, starring Matt Damon. As such, it was reminiscent of “Valkyrie,” which became a Tom Cruise megavehicle rather than a taut Costa Gavras-style thriller. The same for last year’s Russell Crowe thriller “State of Play.”

The lesson: Some movies deserve to be small.

Then there’s another category exemplified by “Greenberg,” which should not only be small, but downright invisible.

Greenberg,” directed by Noah Baumbach and starring Ben Stiller, is so aggressively “cool” that when I left the theater I had frostbite. Some New York critics are high on “Greenberg,” but that’s because they covet depression.

Baumbach’s first movie, “The Squid and the Whale,” made some of us feel that he was a young Woody Allen. But Woody actually believes in delivering a laugh now and then. Baumbach disdains punchlines. If his characters seem exasperating, Baumbach argues, that’s the way people really are. The movie is really about Greenberg’s inability “to get out of his own way.”

So how do we explain to this filmmaker that he’s got to learn how to get out of his own way?

Baumbach could make some good movies if he wasn’t so obsessed about reminding us that he’s much cooler than the rest of us.

Cool is fine. Chilly is disturbing.