Last week, I asked my friend how he planned to open a stand-up routine he was preparing for. He hopped to his feet in the bustling public area we were in and shouted, “A guy walked into the Civic Association in Binghamton and shot 13 people!” All too often, blunt insensitivity passes for “dark comedy.” My friend, innocently, hadn’t made the distinction; I advised him to change his act, and he did. It’s too bad that Jody Hill, who wrote and directed Observe and Report, apparently received no such consultation.

There’s a kernel of genius in Hill’s idea—using a mall cop (who isn’t Kevin James puttering about on a Segway) to parody vigilantism—but Hill doesn’t turn that kernel into popcorn; he detonates it with TNT. Sometimes the shockwaves push you backward laughing, but sometimes you wonder if Hill seriously thinks he’s making a joke. We open on a flasher running amok at a suburban mall. The chief of security, Ronnie (Seth Rogen), treats the case with the utmost self-importance. For anyone who’s seen Anchorman or “The Office,” this fatuity is familiar; but rather than following convention and making Ronnie a bumbling blimp with a baby brain and a heart that gets more properly aligned as the movie goes on, Hill explicitly has Ronnie inform us that this bully is bipolar and was a child with special needs. Are Ronnie’s pompous delusions of authoritarian grandeur—which he eventually consummates—meant to be attributed to his illness? In Martin Scorsese’s Taxi Driver, Hill’s acknowledged take-off point, the hero-driven-to-violence is Travis Bickle (Robert De Niro), a Vietnam vet-cum-Underground Man killer-cabbie; but neither Scorsese nor Paul Schrader, the screenwriter, assigned their protagonist any specific affliction other than the woozy cultural climate of the 1970s.

When Hill brings in real disorders as a jokey pretext for criminal delusion and anomie, one starts to wonder whether the writer-director is in any position to mock the delusional—Observe and Report goes from showing us a pervy goofball opening his trench coat to expose his junk to Ronnie slaughtering a half-dozen junk dealers in front of the adolescent son of one of the victims. The tone is so wobbly that it’s as if the filmmakers had shot each scene from a different draft of a heavily revised—or maybe not heavily enough revised—script. When Ronnie, with his clay-brained brutishness, flashes red lights of realistic menace in this sunny lotus-land, the incommensurability of character and setting is queasily off-putting. Ronnie aspires to be a cop, but for no moral purpose (sane or otherwise); at least Travis Bickle thought he was doing the right thing. Likewise, Scorsese and Schrader provoked one’s empathy and intellect; Hill just provokes your autonomic responses. His shock cuts and hyperbolic effects are hilariously outré, but clever dark comedy they are not.

Because this is only Hill’s second film—following The Fist Foot Way (2006) and a few episodes of “Eastbound & Down,” which he co-created—part of his problem is inexperience. Why else would he turn Dennis (Michael Peña), Ronnie’s doting protégé, into a cold-hearted thief? It makes no sense in character terms, and it throws a wet blanket over an audience primed to like its jerry-curl’d Sancho-Panza-in-Aviators. Even worse, the betrayal scene is staged dramatically; the editing and plotting are often sloppy, but the awkward pathos of this scene is a true depressant. And the word “fuck” is used so many times that it loses whatever teeny edge it retains; trying to wring a titter out of the f-word is a truly desperate stroke in 2009. Hill doesn’t think of Observe and Report as “a disposable comedy … where there’s no greater subtext,” but on the evidence of the film alone, one may think the director very careless both technically and ideologically. According to Hill, “I hope people feel themselves caught up in a Cameron Crowe moment, but the visuals are so fucked-up that it kind of produces a really uncomfortable feeling. Like, people applaud and then they stop: ‘Wait, what the fuck am I applauding? He just murdered somebody.’” The audience I was in seemed to just keep applauding.

Observe and Report cannot find its middle ground between the giddy-adolescent humor of the Apatow productions (with which Rogen is associated), the “awkward” comedy of manners à la Larry David, and the self-critical obsessiveness of Scorsese flicks like Taxi Driver and The King of Comedy. Hill simply hasn’t yet developed the delicacy of tone or feeling to pull it off. If, as Hill hopes, you do ask yourself what the fuck you’re applauding, you end up pondering in a vacuum: Ronnie is a hollow, inapt representation of the zeitgeist (or sufferers of bipolar disorder). Hill slathers on the ambiguity, but skimps on the subtext. It’s a positive sign that a director wants to make a genre film that transcends its commercial limitations, but Observe and Report plays like a discursive speech read aloud by an arrogant dyslexic. A movie cannot be credited as socially conscious if it blames societal violence on mentally ill individuals.

But even though so much of this film is stuck in a lowbrow Twilight Zone, you don’t leave it bereft of laughter. Before it was revealed that the build-up only results in bird-brained nihilism, I (alone, it seemed) laughed at certain nuances that Rogen pulled off in his readings, such as when he says—with his charming big-boy smile—that he wants to enact justice as an agent of God. It’s another instance of misplaced gravitas, but it came from Rogen’s deadpan equanimity and not a visual thud. The actor has recently lost weight, but his plumpness here makes him a teddy bear, and makes him seem harmless even when the movie says otherwise. Rogen is certainly no De Niro, but he retains some of the soft-boiled charm he had in earlier roles—despite the fact that he’s been stuck with a character whose heart is as empty as his head.

As Ronnie’s alcoholic mother, Celia Weston deserves special distinction. Though it struggles with much of the movie’s questionable taste, Hill’s amateurishly variable tone somehow supports alcoholism as an object of humor. Maybe it’s because Weston delivers predictable duds with such exquisite timing and naturalism that you’d think she actually had a flask on set. She transcends the wino stereotype by implying a backstory; when the mother gives her son the old follow-your-dreams treacle, she fouls it up—not because she doesn’t care, but because she thinks that that B.S. is how she’s supposed to show she does. The scenes between Weston and Rogen give the film a little twinkle of humanity; Hill, like Ronnie’s mother, stumbles through the loving-family B.S., but allows himself to subscribe to it. Without it, the movie is cold as an icicle, if not exactly as sharp.

It’s easy to write off criticism of Observe and Report as simply P.C. hot air that open-mindedness failed to refrigerate, but that’s simply not my point of view. Virtually anything can be funny in the right context; but Hill often fails in presenting that context or, really, any sustained context at all. If you want to see great black humor on themes from Taxi Driver, you should rent Taxi Driver.