Mindfulness’s moment is here. One million Americans are taking up mindfulness meditation each year. It’s in the conference rooms at Twitter, in schools and hospitals, and helping traumatized soldiers. And the scientific data on the efficacy of mindfulness-based interventions has become so compelling that insurance companies are starting to cover them.

The backlash is here, too. Buddhist purists are dismayed by one-percenters using mindfulness to get even richer. Skeptics say that meditation’s benefits are being oversold and overhyped. And critics say that celebrity meditation-boosters like Arianna Huffington and David Lynch offer more flash than substance.

All of these people are currently in the Marriott Copley in Boston for the International Symposium for Contemplative Studies (ISCS). There are bestselling authors here (Jon Kabat-Zinn, Daniel Goleman), top-level Buddhist celebrities (the Dalai Lama, Roshi Joan Halifax), and even Arianna herself. There are also legions of young researchers investigating meditation’s neuroscientific, behavioral, and philosophical effects.

With the explosion in mindfulness—the cover of Time! Government grants!—it feels a little like a victory lap. Yet as mindfulness grows into big business, the cracks are beginning to show.

“We risk being swept up in a marketing mania that is orthogonal to objectivity,” said former Wellesley President Diana Chapman Walsh at the event’s opening keynote, arguing for rigorous “norms, procedures, and evidence” as a corrective to potential enthusiasm.

And yet, in the same speech, Walsh set forth a wildly ambitious agenda for an ostensibly scholarly/scientific conference: to bring about “awareness-based systemic change” so that all people recognize their “intertwining with all life on Earth” and work to prevent climate change.

That kind of rhetoric is par for the course at a left-wing activism conference, but even setting aside its political naiveté (Are conservatives supposed to be on board? Or just made extinct?), don’t such aspirations threaten the objectivity of the scientific study of contemplative practice, upon which Walsh herself insisted?

These tensions run throughout the conference, but also throughout the “mindfulness” movement that is now sweeping America. Is mindfulness Buddhist, or secular? Are researchers objective, or are they motivated (tainted?) by their personal affection for meditation? Is mindfulness really ready for prime time?

On the first question, the address by the Dalai Lama—Nobel laureate, leader of the largest occupied nation on the planet, best-selling author of cuddly books like The Art of Happiness—embodied these contradictions. On the one hand, the Dalai Lama is, as he describes himself, “a Buddhist monk.” People call him “Your Holiness.” And he has been involved in the Mind and Life Institute, the sponsor of the ISCS conference, from its inception.

On the other hand, the Dalai Lama insisted that one can differentiate between scientific research and (again his term) “Buddhist business.” “We are not talking about past lives, heaven or hell, or nirvana,” he told the crowd, “but simply how to build happy individuals, happy families, happy societies, and ultimately a happy humanity.”

Fair enough. But the Dalai Lama added that “When I tell people some Buddhist teaching, they don’t pay attention. When I tell them the scientific data—then they pay some attention.” So is science just another upaya, or skillful means, to spread Buddhist teaching?

Then again, is Buddhism even a “religion” as Westerners understand it? Some streams of Buddhism have the trappings of worship, rituals, and semi-divine beings, but others do not. Many practitioners—the Dalai Lama included—emphasize that the Buddha’s core teachings are naturalistic, and meant to be verified empirically, rather than taken on faith. And the core goals of Buddhism—liberation from suffering, for example—have been thoroughly transformed by the contemporary secular mindfulness movement, which is largely about stress reduction. Maybe this watered-down Buddhism has been watered-down enough to play in Peoria, and assuage the concerns of conservative Christians.

A more controversial claim was made by the well-known scholar of Buddhism Alan Wallace, who said that “the notion that science is the sole arbiter of truth is unwarranted” and claimed that there is evidence for the non-materiality of the mind based on recollections of past lives, “the validity of which can be rigorously tested scientifically.”

It’s that kind of claim, and some academics’ proposal that “first-person knowledge”—i.e., my personal spiritual experiences—are as important to understanding religious experience as “third-person knowledge” (rigorous historical and scientific analysis), that has more conventional scholars, let alone scientists, concerned.

For one thing, the subjective/objective distinction is fundamental to Western notions of scholarship, and science itself. Good riddance, say many—but such distinctions have brought us things like, you know, medicine. (Good riddance to that too, some might say.)

For another, scholars/practitioners’ enthusiasm may be tilting the data in exactly the way that Walsh worried about. For example, a “systematic review and meta-analysis” of 47 mindfulness studies that was published in the Journal of the American Medical Association earlier this year “found no evidence that meditation programs were better than any active treatment (i.e., drugs, exercise, and other behavioral therapies).”

Ouch. Mindfulness is now big business—a drop in the bucket compared to mainstream medicine, to be sure, but still hundreds of millions of annual dollars in government grants and significant investment by corporations and capitalists as well. And it’s no more effective than jogging?

Some scholars, notably Willoughby Britton of Brown University (in whose department I am a visiting scholar), even argued at ISCS that meditation can be bad for you, especially if you dive into the advanced methods without a reliable teacher.

To be sure, not everyone agrees with this review of the data. There have been more than 1,400 studies of mindfulness, showing significant effects on problems like memory, immune response, self-control, attention, recovery from addiction, and emotional resilience. Surely the data can’t all be wrong.

The fact that these tensions are present even at the epicenter of the mindfulness world is telling. The bloom is off the rose. The first generation—that of scholars like Richard Davidson who bravely dared to ask questions that the scientific community thought were garbage—is now yielding to a more fractious bunch, who have widely different ideas about what we’re even doing here.

Some, it’s clear, just want to teach more people meditation; they’ve enjoyed the benefits themselves, and they want to spread the gospel. Others are clinicians, sincerely interested in anything that can help their clients stop suffering. Some are hard neuroscientists, aware that this is a cool cutting edge of research.

But I’d bet that everyone filling the Copley Marriott is surprised at where meditation has come so far, and productively unsure of where it’s headed.