One of the first things you’d learn in any Intro to Buddhism course is that most Buddhists alive today are part of the Mahāyāna tradition, in which one aspires to be a bodhisattva (and eventually become a buddha). Mahāyāna is the majority tradition because it’s the one practised in Japan, Korea, most of Vietnam, and China including Taiwan and Tibet. (Tibetans sometimes refer to their tradition as “Vajrayāna”, but they know that that’s still a form of Mahāyāna; there are no non-Mahāyāna Vajrayānists.) The name “Mahāyāna” (translated as “Great Vehicle”) is not in dispute; everybody agrees that that’s the preferred term. That part is easy.

Now here’s a question: what do you call all the other Buddhists?

Your typical intro Buddhism course gets around that question pretty easily, because there’s a simple answer if you’re exclusively talking about Buddhists today, in the modern era. As of about 1850, basically all the non-Mahāyāna Buddhists in the world identified as part of the Theravāda tradition, practised throughout Sri Lanka and mainland Southeast Asia. The only Buddhists who might identify as something else are more recent modernist Buddhists of one stripe or another – hippyish Western Buddhists who don’t want to be pinned down to specifics, or perhaps B.R. Ambedkar’s Navayāna – and they understand they’re doing something new and a little weird. (“Navayāna” means “new yāna”.) In general, it’s pretty reasonable to say that the Buddhism existing in the past thousand years or so has been divided into the two traditions of Mahāyāna and Theravāda.

But go back before that, and things look very different.

Read a traditional work of Mahāyāna scholarship, like Künzang Sönam’s excellent Tibetan commentary on Śāntideva’s metaphysics chapter (now available in Douglas Duckworth’s solid English translation), and you’ll find a lot of discussion of non-Mahāyāna Buddhism. But not only will you not find the word “Theravāda”, you will not find any references to Theravāda tradition – you certainly won’t find the name, and you won’t find its greatest philosopher Buddhaghosa, its histories, or any of the Theravāda works produced in Sri Lanka or Southeast Asia over the centuries. Non-Mahāyāna Buddhism is instead represented by the Abhidharmakośa of Vasubandhu: a text from the Sarvāstivāda (“everything exists”) tradition, which was neither Mahāyāna nor Theravāda.

Theravāda, for its part, means “Way of the Elders”: the name indicating that Theravādins have believed themselves to be preserving the Buddha’s pure teaching, undisputed by later influences. But this Way of the Elders was a self-conscious Sri Lankan movement, an attempt to return to the original teaching in the midst of other traditions – an innovation through conservatism. Even if you accept the Theravāda claim that they are preserving pristine original Buddhism, you must also recognize that that supposed pristine original Buddhism – the Buddhism found in the early Pali texts – never called itself “Theravāda”. It didn’t have to, because there weren’t other Buddhist traditions promoting an alternative understanding.

Self-consciously Theravāda texts, like the Mahāvaṃsa historical chronicle, set Theravāda aside from other Buddhist traditions. But here’s the thing: they never mention Mahāyāna! It’s just not on the radar. The Mahāvaṃsa’s fifth chapter mentions eighteen schools or sects competing with the Theravāda. The best known of these is the Sammitīya or Vajjiputtiya, now better known as Pudgalavāda – the school that weakened the doctrine of non-self by saying human persons are actually real. It’s in there, along with many obscure schools I hadn’t heard of anywhere else – but Mahāyāna isn’t.

The point is that there were many, many different Buddhisms that were neither Mahāyāna nor Theravāda. We can think of these now as lost Buddhisms, analogous to the lost Christianities. Given the prevalence of Mahāyāna today, it’s common to take the standard Mahāyāna practice of lumping these together with Theravāda under the name “Hīnayāna”, which means “Lesser Vehicle”. Because Mahāyāna is so different from the other Buddhisms, it does make sense to divide Mahāyāna from non-Mahāyāna – but not to call the non-Mahāyāna schools by a term deliberately created to insult them.

The name “Lesser Vehicle” is every bit as pejorative as it sounds: it is intended as a self-righteous promotion of Mahāyāna that proclaims how much better and greater it is than all those pathetic little non-Mahāyāna schools. So giving non-Mahāyāna schools the name “Hīnayāna” is like giving non-Theravāda schools a name that means “random crap you just made up that has nothing to do with what the Buddha actually said”. Both names would indeed reflect how Mahāyāna and Theravāda respectively view other Buddhisms, but they’re not exactly appropriate if we’re trying to understand or learn from multiple Buddhist traditions. The prevalence of the term “Hīnayāna” tells us just how widespread the Mahāyāna movement became, but it shouldn’t be used by anyone other than Mahāyāna theologians. For this reason, many scholars of Buddhist India will refer to those other schools as mainstream Buddhism, reflecting Mahāyāna’s status as an unusual offshoot. Though the most neutral way to refer to schools that are not Mahāyāna would simply be to say, non-Mahāyāna.

The name isn’t the most important thing, though. Rather, it’s worth reminding ourselves of the non-Mahāyāna, non-Theravāda schools of Buddhism because of the possibilities they can still open up to us philosophically: the lost Buddhisms can help open up new Buddhist ways of thinking that might otherwise have been closed to us. At this year’s IABS conference in Leipzig, for example, Buddhist philosopher Laura Guerrero turned to the long-gone Vaibhāṣika school’s theories as a way to harmonize Buddhism with the powerful emergentist theory of consciousness. The Vaibhāṣikas were a sub-group of the Sarvāstivāda – the group that the Tibetans recognized as the most important non-Mahāyāna group, even though they’re not around now.

For my part, I think the most interesting of the lost Buddhisms is the Pudgalavāda. Today most of us English-speakers are expressive individualists, who take it as hugely important for a good human life that people be themselves. On the face of it, expressive individualism does not seem like it would be a good fit with a Buddhism that proclaims there is no self. I have tried to find various ways to harmonize the two, but it can be a tricky project. The Pudgalavāda might well be a helpful guide in figuring it out: a school very popular in the classical Indian Buddhist world that thought human persons were real after all.