A while ago, on a forum, the question came up of the mood-swings that most writers suffer about their writing: sometimes it seems as if the shift is always towards the negative, from the satisfaction of having written something which says what you want to say, means what you want it to mean, towards the realisation that it doesn't, really, do either of those things very well. And what's more it's clichéd, badly punctuated, unsaleably odd and drearily conformist...
These days we're less inclined to tear up manuscripts in a rage - tearing up laptops comes expensive - but the impulse may be there: the finger hovers over "confirm delete", so you don't have to go on having your "failure" sitting, leering at you from your hard drive. But when someone asked if I didn't suffer from today's good work becoming tomorrow's garbage, I had to say no. Or rather, "No, but Yes," swiftly and inevitably followed by "The thing is, it's not as simple as that."
a) No, in the sense that I don't think in terms of "good versus garbage", because that gets you nowhere: those sorts of value-judgements come from a place which is all about your general state of mind and mood and self-esteem, and not much, necessarily, to do with the actual quality of the writing in this piece now. They're your Inner Critic talking, not your Inner Editor. "Good" vs "bad" also so easily spills into a self-esteem-focused judgement of yourself - that you should be ashamed of producing bad writing - which is all utterly irrelevant to the task at hand.
b) Yes, in the sense that I do think in terms of "works" versus "doesn't work". And then I think about what makes a doesn't-work piece not-work. And once you've done that, you're halfway to making it work because, as Richard Sennet says, a large part of craftsmanship is the process of problem finding; once you've found the problem, solving it is straightforward, if not easy.
Also, I really do have "creativity is mistakes" tattooed on my brain these days, just as Grayson Perry has it cast into a beam in his workshop. So if, the next day, I read something and think, "Gosh, that really, really doesn't work," then I just think "Okay, there's a long way to go still. Damn, I hoped it was nearly there. Now, what the hell am I going to do about it?" I may be extremely fed up, but that doesn't mean I classify the writing as garbage, just as some of the process writing that was inevitable along the way. It's just work-in-not-quite-as-fast-progress-as-I'd-hoped. That is, though, one reason I'm extremely conservative about who sees my work in progress. They're all people whose opinion I value and respect, but also people I trust to express that opinion in ways which open my ears and mind to what the piece needs now, rather than making me close down and shut off defensively.
Mind you, I rarely think all that differently, in global terms, about a piece the next day from how I thought about it when I was writing it. I'll certainly make a note today, on yesterday's work, that says "Is this really clunky?" or "Not convinced she'd do this", but that's not calling it garbage, that's just me being a writer. It'll probably still file clearly under the same works/doesn't-work heading for some weeks. Essentially I'm still inside the bubble, and my only judgements are about the detail of how well it is or isn't fulfilling my sense of what the bubble is, until I've finished the first draft of the whole project, and slapped it into rough shape.
Obviously there are a hundred things that I'll change in revising when I do come to revise it weeks or months later: it may not look very much at all as it did yesterday. And that's when I start making judgements about whether it works overall - whether this project was worth doing - whether the draft is too lumpy/quiet/melodramatic/trivial/obvious/obscure/badly structured/long(it's never too short!)/meandering/abrupt... And the judgement can still be that this project was always inherently limited in what it could ever be. So be it. I couldn't find that out, without working it out to the full. Or the judgement could be that the project has lots of potential, but I haven't fulfilled that potential well or fully. It's time for a total rebuild. So be it; you buy Scrivener, and get on with it.
But even that happening shouldn't persuade a writer that what they write is all, always garbage: just that with the skills they have and the project they tackled, they haven't made it work yet. It's true that kind of thing happening persuaded me many years ago that I'm slow and stupid. Almost every project that I've really made work has been at least my second go at it. A Secret Alchemy has important elements which I first explored in every single one of its seven predecessors, for example. Some of them were elements that demanded skills I didn't have at the time, and which I only learnt on the intervening projects. Other elements just weave better into the new cloth. I still do things really badly, often. It's frustrating and miserable at the time. But, long term, I've come to terms with the fact that my creative life will always be like that. Creative work involves a lot of "mistakes" - which aren't mistakes at all, at their heart - and like nature itself it needs to be wasteful, in order to be fruitful.
All this is different, of course, from the bigger decisions about whether you really should go on with this novel, or start this writing course, or just spend this much of your life locked away writing. Or should you instead go and remind yourself what your partner and children look like, get a proper job, and revert to being a one-Sunday-a-month writer? Your own, cumulative judgements about individual pieces of writing and your relationship to them, and the conditional validation of those you respect, are of course the stuff of these bigger decisions. But collecting together those judgements, positive as well as negative, is a different business, to be done warmly and humanly, on a good day, not a bad one, and with your Inner Critic safely locked in the garden shed.