Question: How many butterflies have to flap their wings in China before Ashton Kutcher finally breaks down and takes some acting lessons? That whole ‘‘affable dope’’ thing might knock ’em dead in ‘‘Dude, Where's My Car?’’ but it makes for some painfully unsound emoting in ‘‘The Butterfly Effect,’’ a supernatural morality play that just as easily could have been called ‘‘Metaphysics for Dummies.’’

Even during the movie's darkest moments, Kutcher (TV's ‘‘That 70s Show’’) appears to teeter on the verge of self-effacing buffoonery as Evan Treborn, a scruffy psychobiology student who turned out pretty well despite a difficult childhood, one that included sexual abuse, frequent blackouts and a schizophrenic father who believed he had godlike powers to change the past.

The apple, as it turns out, didn't fall far from the tree. While pouring over old journal entries he scribbled down as a troubled kid, Evan discovers that he has the ability to project back in time and inhabit his body as a child. And not only that, but side-step some of those horrible childhood experiences that continue to haunt his adult psyche: an episode with a neighborhood pederast, a prank gone tragically awry, the cruel and gruesome murder of his dog.

As anybody with an associate degree in sci-fi causality will tell you, there's a price to pay for Evan's meddling: With every trip into the past, the present as he knows it is dramatically altered, often with disastrous consequences for him, his long-suffering mother (Melora Walters), his childhood girlfriend (Amy Smart) and his reclusive cousin (Elden Henson). No matter how many trips Evan makes, or how many past regrets he troubleshoots, someone always gets screwed. One time, he even gets turned into a preppie frat-turd with an evil goatee like the one Spock wore in the ‘‘Mirror, Mirror’’ episode of the first ‘‘Star Trek’’ series. The horror.

It's an intriguing premise, in a low-rent ‘‘Twilight Zone’’ kind of way, but writer-directors Eric Bress and J. Mackye Gruber (who jointly penned ‘‘Final Destination 2’’) prove incapable of exploring it beyond the macabre: murder and mayhem, dismembered limbs, prison rape and other things that make us shudder and wince. In other words, unless time travel is a recurring issue in your life, the movie has absolutely nothing worthwhile to say, no single, emergent theme.

Neither is it true to its roots. The title, borrowed from a popular aphorism of chaos theory, refers to large, event-level effects wrought by minute causes, like the flap of a butterfly's wings. In Evan's universe, nothing changes unless you stab someone in the back or plunge spikes through your hands, and there isn't anything minute about that.