Take my attempt here with a grain of salt. Many book length treatments have argued different sides of this. I only hope that this can serve as a starting point for your own experiential investigation that is somewhat less confused, as well as make future engagement with other interpretations less confused.
To reiterate and emphasize. The above sentence full of Pali terms is about detectable mental events within the stream of physical sensation, feeling tones, mental talk, and mental image that makes up moment to moment experience. If something sounds weird it's just that you've never reified it before because it goes by very fast (10-40hz range). Meditation is about training the mind to be able to notice these more subtle events and then instructions for noticing certain things about the causal relationship between these subtle events and how good your moment to moment experience really is. The purpose of meditation is not to become a really good meditator, to experience certain cool temporary states (though some are helpful), etc. But direct insight into the basic building blocks of your experience.
Tanha is usually translated as desire or craving but this is wrong and misleading. Tanha is more literally translated as 'fused to' or 'welded to'. It immediately follows the mental moment that you zoom in with the attentional aperture on something. It could be that a flower or an item on the shelf at the supermarket captures your attention, or you turn your head to catch more detail as you pass by an accident on the road. Many hundreds of thousands of such events take place in the course of a single day. With most of them attention then relaxes and makes space for the next thing. But with some small proportion you find the mind doesn't quite 'unclench' from the object or some aspect of the object. This tension aspect is why it is sometimes translated as ‘grasping’ which is closer. Imagine something you aren’t finished with being pulled out of your hand and you tensing your fingers to resist.
Anicca is translated as 'impermanence' but this is off and it's worth pointing out how this happened. In the 19th century when a lot of initial western translations of Hindu traditions was occurring, much of the translations of Buddhist texts were done by Sanskrit scholars. This is interesting because it was foreseen as a problem by the Buddha. There is a discourse where Sanskritists come to the Buddha and he specifically warns against conflating Pali and Sanskirt terms as highly confusing (because there is a bunch of overlap in affixes and grammar)! He tells them not to translate the teachings into Sanskrit because it will lead to nothing but problems. In modern times we are saddled with exactly this having come to pass. The Pali words for impermanence are Adduwan or Aniyata and the Buddha uses these terms elsewhere. This happened due to Sanskrit translators thinking that Anicca was the same word as Anitya, the Sanskrit word for impermanence. So what is an actual translation of Anicca? Something more like our inability to maintain things as we like. This sounds philosophical, but there is a specific mental event it points to, namely the inverse: Nicca. And this gets at an extremely important point in how this stuff works. If suffering were truly just coming in from the outside in thousands of different forms (i.e. the way things seem on cursory inspection) then we wouldn't have much hope of a single intervention helping us. Nor would we be confident in any such intervention since some new form of suffering can always show up. But if suffering is a result of something we're doing, then if we can figure out how to stop doing that, the suffering stops. Which we can confirm for ourselves in moment to moment experience. So Nicca is our tendency to believe that things could or should be maintained to our satisfaction. This is an identifiable mental event in how we reify an object or concept. Ignoring the very ephemeral nature of moment to moment experience in favor of only noticing those aspects which do occur as stable. Spotting it for yourself is very powerful. If this were just considered on its own without the teaching of the antidote it might be related to feelings of hopelessness. That there is no hope of maintaining the conditions that lead to things we like. Thus, the flow of positive and negative experiences are undependable, indefinite in duration, intensity, and frequency. That our hopes of forcing them to be stable with our mind will be in vain.
Anatta. Oh boy where to even begin? Like Anicca, Anatta was translated by Sanskritists as the same as the Sanskrit term Anatman. A literal rendition of Anatman is ‘no-soul’ but is also generally interpreted as ‘no-self.’ This has probably lead more people astray than any other mistranslation. And again we have a passages from the Buddha warning against this specific problem. People come to the Buddha to argue about self vs no-self doctrines and he repeatedly says that if you hold a view of the self as existing then you are in error, and that if you hold a view of the self as not existing you are in error. The first major milestone on the Buddhist 4 path model is the release from having any particular view of the self because the whole point of the first milestone is that you’ve improved your understanding of the causal relations between mental events enough that you’ve seen that this distinction was predicated on a confused concept. Furthermore, if we were to take the translation of no-self as valid a bunch of discourses don’t even make grammatical or logical sense. Of course not making logical sense is considered a feature by mindlessness schools.
Like Anicca, Anatta is pointing to the inverse of a specific mental event, Atta. Atta is a little hard to translate, we can translate it as more like a verb or more like a noun (Pali is weird). If we see it more like a noun it might be translated as ‘essence’ and if we translate it like a verb it might be translated as ‘to take/have control/ownership of.’ Together we have the notion that if something has a real immutable character or ‘essence’ to it that we understand, then we can really control it and that this control won’t be subject to change. Anatta is to point out the error in this way of seeing things. The point is to notice the mental event that represents objects or concept as though they could or should be inherently or essentially controllable/ownable. If this were to just be taken on its own without the teaching of the antidote it might be called helplessness, that things are without the possibility of being controlled. We use the mind to falsely pretend we are more in control than we are. This faculty of mind feels like one of those child’s car seats that has a fake steering wheel on it, made famous by The Simpsons opening credits. The mind either deludes itself by carefully moving the fake steering wheel in line with what it sees so that it can pretend it has control, or it strains itself throwing its weight ineffectually into cranking hard on the wheel when the car goes places it doesn’t like.
And this isn’t an argument that trying to gain a better understanding of causal relations so that we have real steering wheels instead of fake ones is bad. Again, the point is to spot the mental moment of playing with the fake steering wheel instead because it is easier. Now, this must relate to theories of self somehow, it couldn’t be that everyone is totally deluded about this central aspect of Buddhism right? Well, yes and no. Self-making, identification, separating self from world, and insight into such are very important for decreasing suffering. But rather than the philosophy that many/most delve into we have something comparatively simple, just the mental act of Atta applied to ourselves! So we come to believe that we have an essential nature that our dissatisfactions are accruing to. We believe that we ‘obviously’ have ownership over ourselves and that we ‘should’ be in control of ourselves. It’s just that this isn’t how things are in moment to moment experience, so it causes a lot of problems. People get really caught up in this set of insights, but at its core it really is just the specific moment of a mental act that we learn to identify (ha) and stop doing as we gain awareness that it isn’t actually helping in the way we thought.
(Breakout section for epistemologists, skippable if you aren’t into analytic philosophy)
The above section on Anatta seems to be a place that Buddhism comes unavoidably close to metaphysical claims. No inherent essence sounds like it might be a form of idealism, like a denial of there being any real stuff ‘out there’ that follows fully structured rules (like Maxwell’s equations, say, or any other strong invariant). Many of the people reading this would likely consider themselves Quinean naturalists, materialists, etc. Consider the difference between how an invariant like Maxwell’s equations actually shows up in moment by moment experience vs the inference that they describe a naturalistic world (i.e. unified, even if we don’t always have efficient bridges between different successfully predictive representations). In moment to moment experience we experience noisy measurements. When we do experiments of successively higher resolution we see that the error bars converge towards the relevant invariant equations. We infer that the invariants are what is really out there. The uncertainty is in the map (with the human nervous system as noisy map maker) not the territory. This is totally reasonable. In the Buddhist conception we aren’t concerned with the validity of successive maps that we build for different purposes and what they say about how reality ‘really is’, but with the nature of the convergence process itself i.e. a map making consideration and not a territory consideration.
What Anatta should be taken to mean in relation to philosophy of science is more like ‘you should never have a prior that is non-updateable by sense data.’ This immovable prior would be something like being convinced that one had penetrated to the real ‘essence’ of something. In practice it would be taking our successively better models of control with a grain of salt so that we don’t shit a brick when they suddenly fail out in the tails (tails come apart!). My sense of why this happens in the first place is that if we’re going to be propagating lossy compressions for efficiency anyway, then it would be really nice to just be able to multiply by one or zero rather than some point estimate or, even worse, trying to properly combine full distributions. This probably isn’t a big deal in the short term, but by default we have too many zeros and ones as placeholders in the belief network at a super low level. This is just another way of saying that we seem to reify things in an improper manner, leading to problems where higher level representations don’t orient our attention properly towards real causal levers. This sort of pretending that lossy compressions are actually lossless (X is Y) probably contributes to our transfer learning, but Awake people seem if anything above average at using metaphors to illustrate causal relations while not getting confused by them.
Also, while irrelevant to our human situation, even a jupiter brain with a TOE should probably have knightian uncertainty. ;)
Nibbana is generally thought of as an exalted state of being that is free of all suffering, all desire, etc. etc. It, along with confusions arising from the previously mentioned mindlessness schools, leads to people assuming that Buddhism is wireheading. The best translation of Nibbana (for the purposes of practice) IMO is ‘cooling down.’ If we think of the above strategies as a sort of tensing, a sort of effortful exercise, a sort of heating up if you will, then we can contrast it with untensing, non-efforting, cooling down and relaxing. The simplest way to think of this is that Nibanna is the opposite of Tanha. Often translated as the mind ‘inclining towards relinquishment’ (of that which was grasped). The nature of this experience is relief. And here it means not only relief from the particular stimulus that was stressing us out, but the (normally experienced temporarily) relief from compulsive grasping, the relief from wanting things to be other than they are, relief from the belief seemingly pressing down on us that we need to act just for things to be okay. A kind of happiness that comes from a halting of believing that we need to get happiness by arranging things to match up with mental projections. And I want to emphasize here that often with all of these various Buddhist distinctions, we often miss them because our mind is focused on the horizon, looking for special spiritual sensations or understandings and not noticing the mundane ways these things are already showing up in experience right now. The comfortable silence with a good friend. The satisfaction of a good meal when you ate neither too much, nor too little. The feeling of post-orgasm. The concept of Nibanna points the mind to the idea that maybe these aren’t specially fabricated states that are unsustainable so much as the natural quality that arises when you aren’t grasping after stability, control, and satisfaction. And again, this is a mental event and not a life philosophy.
Upadana is literally translated as ‘fuel’ but also is used in gardening metaphors to mean seeds as well as having connotations around ‘pulling towards oneself.’ I already alluded to why this is an important concept with the idea of maladaptive strategies that generate their own fuel. Upadana is a mental event that immediately follows Tanha. It can be thought of as the opposite of Equanimity. We instinctively pull or push away aspects of mental objects/representations that we do or don’t like. We try to ascertain the aspects of objects that are stable, controllable, satisfying so that we can own, or associate with those aspects. We ignore or try to push away aspects of the objects that make us feel hopeless, helpless, worthless, empty. This carving up of objects has little to do with how they are in the world, so the mental stories we build out of these carved up objects are also incoherent. One way I’ve found helpful for spotting this is to notice that what is really happening in moment by moment experience is that I’m very rapidly doing a bunch of inferences on the object, and then throwing out the original data and only keeping the results of these inferences.
Sankhara. Just like elsewhere, Sankhara can be translated as either 'that which has been put together' or 'that which puts together.' Another noun/verb duality. If Upadana is a seed, then Sankharas are the warped houses we build out of the twisted lumber that grows. Living in these poorly made houses we don’t understand why we are miserable. To speak less metaphorically, a Sankhara can be thought of as a collection of mental events put into a story about how the world is. An example would be thinking of things in terms of victims and oppressors. Thinking like this tends to make people angry, it tends to make them feel helpless, and it doesn’t tend to point them to causal levers they can pull to improve their situation. Observing that they don’t seem to be able to help themselves, turning any resources offered into louder amplified shouts of how miserable everything is rather than improving things, other people tend to turn away from helping them. This further fuels the world view. In Buddhist psychology, the victim-oppressor mindset is called the Hell Realm because it is considered a particularly nasty maladaptive strategy. Not only because it is miserable for people caught in it, but because it reinterprets signs explaining how to get out as tricks, attacks, etc. (See: my frustration with wireheading objections ;) It is said that the most tragic aspect of the hell realm is that none of the gates are barred.
Let’s take a crack at the entire sentence again. By default, the mind becomes stuck to mental representations that have more to do with our desires than how things really are. This leads to aversive experiences of emptiness, hopelessness, worthlessness, helplessness when we bump into evidence about how confused we are. We come up with plans for avoiding these experiences, but these plans don’t really work, leading us to repeatedly encounter flashes of the undesired experiences. Our response is to try to push on the plans even harder, which doesn’t work. But once we get wise to this process we can incline in the opposite direction, pushing less hard on experience. The relief from doing this wakes us up to the idea that we’ve been fueling the above vicious cycle and live in a house built from these sorts of knots of confusion. Instead of trying to hold the house together with constant maintenance while simultaneously trying to find the exact right decorations, we start tearing down the house. We discover that the very idea that we needed an unchanging, beautiful house that definitely belongs to us was just another of the confused knots. House building, maintenance, and dwelling becomes just another human activity that can be engaged with or not as is convenient. As these activities were previously taking up huge amounts of our attention and resources, we find ourselves much more relaxed and able to enjoy things. Because others still live within the paradigm of seeing everything as related to houses, they are inclined to perceive you as living in a shiny spiritual house, and try to figure out which sets of maintenance activities and decorations will grant them these ‘spiritual’ advantages.
(There’s a joke in here somewhere about house-holders)
So when we engage with Anicca, we might think that in the long run of course things can’t stay stable. No, not in the long run! Right now in your direct experience images of words and mental sensations of meaning are flickering by. This is the Anicca to investigate! When we engage with Dukkha, we might think that there’s a certain sense in which of course things aren’t satisfying. No, not in a certain sense! Right now in your direct experience there are sensations related to aversive feeling tones that are being papered over. This is the Dukkha to investigate! When we engage with Anatta, we might think that of course our sense of what we control isn’t always aligned with what we can actually control. No, not better calibrated models! Right now in your direct experience there is a sense of some sensations controlling other sensations. This is the Anatta to investigate!
These build on themselves. You notice that anything you are aware of is in the process of changing as you notice it. Which means that the sensations of just a moment ago are not the sensations right now. You incline more and more towards noticing this gone-ness rather than the normal arising and sustaining quality that you’re in the habit of paying attention to. With this as a lens you notice that the sensations are unpleasant in various ways. But that’s okay because the moment you notice them they’re already disappearing. With this as a lens you notice the mental motion of trying to control those unpleasant emotions by grasping their essential nature. It seems like it was there all along, and now it too is sensed to be unpleasant, but already passing away even as you notice it. And now you are just in the stream.
Row, row, row your boat
Gently down the stream
Merrily, merrily, merrily, merrily
Life is but a dream
"The three characteristics of impermanence, dissatisfactoriness, and no-self are so central to the Buddha’s teachings that it is almost inconceivable how little attention the majority of “insight” meditators give them. I cannot possibly overstate the usefulness of trying again and again to really discern these three qualities of all experience. They are the stuff from which ultimate insight at all stages comes, pure and simple. Every single time I say, “Understand the true nature of things,” what I mean is, “Directly perceive the three characteristics.” To perceive them thoroughly and directly is to be awakened.
Somehow this exceedingly important message doesn’t typically seem to get through to insight meditators, so they spend much time doing anything but looking precisely, moment to moment, into the three characteristics. They may be thinking about something, lost in the stories and tape loops of the mind, trying to work out their stuff, philosophizing, trying to quiet the mind, or who knows what, and this can go on retreat after retreat, year after year, decade after decade, and of course they wonder why they don’t have any insight yet. This is a tragedy of monumental proportions, but you do not have to be part of it! You can be one of those insight meditators who knows what to do, does it, and finally gets it in the truest sense.