One of the things that bugged me about Buddhism (Zen and otherwise) when I first ran into it was something that is typically encapsulated with the following formulation: The past, the present, and the future are all unknowable. You only know about the past through traces left behind, and those aren't really the past; they're traces left by the past. Likewise, you only know about the present by way of your tiny perceptions of your tiny slice of it. And the future — who knows about the future?
All this stuff bothered me because it seemed like an affront to the scientific mindset that affirms that we can in fact know and predict things about our world. The Buddhist view seemed like nihilism, or defeatism, or at the very least quietism, all of which I can't support. What changed my understanding was something that went hand-in-hand with the deepening of my understanding of Buddhism generally — a better appreciation of the context and the meaning of taking such a point of view, and how it wasn't intended to conflict with a scientific worldview.
Theodore Roszak — not my favorite thinker, but he had his finger on the right thing here — once wrote about how human experience tends to cleave into two general realms, Out-There and In-Here. Out-There is the subjective world, where 2+2=4 and where we need to study engineering to build bridges so they don't fall down when they drive across them. (And when they do fall down, we can generally find out why and learn from the mistakes.) Out-There is shared reality that we all have to live in, so we might as well make it as livable as possible. In-Here, on the other hand, is irrational, subjective, weird. 2+2=FISH. Where we're going, we don't need bridges. All that stuff.
The short version is this: Science is for Out-There; Buddhism is for In-Here. We need different methodologies for each, because the way we deal with ourselves on the inside is by definition not how we deal with everything else on the outside.
Now, nothing says that at some point, we could have a single unified methodology for dealing with Out-There and In-Here. Over the last hundred and fifty years there's been a lot of work — erratic, sometimes wrongheaded, but vital — that attempted to bring scientific understanding to the human mind. We've garnered some valuable and important discoveries from all of this.
But the one problem I have with such work is that it's been devised for the sake of "outside looking inside". It's mostly suited to professionals who make a living helping other people. It works best when you have the training and discipline to apply it, and you generally apply it to others and not yourself. Few people have, or elect to manifest, that kind of discipline. it's tough to apply it to yourself, even if you're someone who has the smarts and the wherewithal to apply it to someone else.
The thing Buddhist teachers emphasize about Buddhism is that it's first and foremost a path of practice. It has theoretical and philosophical components, but they're not what comes first. The main thing is to look at yourself, good and hard, and to cultivate that habit ceaselessly as a way to remove all the ego-logical crap you put between yourself and yourself, and yourself and the real world. You need something practical to make the irrational world of In-Here a little less unruly.
Let me circle back to the first part of this essay. If we talk about the past, present, and future being unknowable, that's just something for In-Here. That's — how to put it? -- a-rationality being used to tame ir-rationality. It's not something we tell ourselves because we hate science; it's something we tell ourselves because In-Here needs different ways to deal with those kind of big, ponderous questions than Out-There.
Maybe you're one of the lucky few who doesn't need, or want, a different approach for In-Here vs. Out-There. Good! But not everyone is like you.
For more on Out-There vs. In-Here, and some fun storytelling to boot, check out my (new!) novel Welcome To The Fold, and showing your support for it by registering at Inkshares and adding the book to your "Follow" list! Failing that, you can always buy one of my existing books, available on Amazon Kindle and in dead-tree format.