I agree with the perspective you're laying out here. These days, I take a slightly more concrete approach to choosing my wardrobe. It still fits the perspective, but the thought process is different.
To decide what to buy, I think about a specific purpose in my life for which I need clothes, and I try to get as specific as possible.
For example, I just started a new job, and I wanted to buy some new clothes for it. Because I already had plenty of suitable shirts, I started to think about the requirements for optimal pants for this application.
I figured that there must be some sort of athletic pant in a professional-looking cut, and as it turns out, there are! I found what I needed at Nordstrom Rack and they worked out great for me.
The key here, however, is that I didn't start by thinking about abstract qualities of ideal pants (i.e. by listing a set of attributes along which pants can theoretically be optimized). I started by thinking about a practical clothing problem in my life, then imagined the abstract qualities of pants that would make them great solutions to this practical life problem. Then I went and found real-world versions of those pants (and some moisture-wicking underwear and socks as well to complete the bike-communting-friendly wardrobe).
Likewise, I recently considered how to deal with shoes for bike commuting in winter. My shoes might get soaked on the way to work. Yet my feet tend to overheat and get sweaty and itchy over the course of the day. I didn't want to carry pairs of shoes back and forth.
At first I considered waterproof sneakers like Vessis, but I found that water can sneak in through the top, and they are very hot on your feet. Then I considered biking sandals, while keeping a foot towel as well as socks and shoes at work. Then I realized that there are such things as shoe dryers, so I can potentially wear breathable shoes, put them on shoe dryers at work, keep a second pair of at-work shoes and some socks to change into, and change back into the dried-out bike shoes on the way back. This lets me get whatever biking shoes or sandals seem like they'd be most comfortable in a particular season, while picking shoes that are optimized for comfort or style at work.
This is how I used to buy clothes. At least in my case I got some hard advice from a friend: I was picking pieces of clothes that were fine in isolation but didn't really come together to create a look/fit that was me and made me look unintentional and thus less good. It also made it too easy to optimize for function at the expense of form to the point of picking things that met great functional requirements but looked bad, like technical hiking pants that met tons of needs other than looking good or fitting my body well.
In order to actually look put together I realized that I needed to take a more global approach to my clothes optimization.
Yes, I agree that if "practical problem in your life" did not include "looking good" or "goes with my other clothes" as design parameters then you'd probably end up in a situation like that. I succeeded at avoiding this problem because I specifically set out to find pants that were good for biking and looked like professional work pants (fortunately I already had some that did). This can be useful: it puts a sharp constraint on the shirts I buy, requiring them to look good with these specific pants. That limitation can be helpful in making the overwhelming number of choices manageable.
Anyone claiming a particular style, brand, fabric, or article of clothing is optimal, full stop, is either lying, trying to sell you something, or confused about how optimization works
That's fair... but also I want to spread the word about my optimal dress. While it's only sold new on StitchFix, there are tons available secondhand (and usually cheaper) on Poshmark, and it comes in dozens of fabrics/patterns! (Search 'Kaileigh faux wrap dress' or just 'Kaileigh dress', in your size.)
It's obviously not actually 'optimal' but it's really comfortable and looks amazing on a lot of people. I own like fifteen in different patterns and have gifted them to four friends of different complexions and body types, and all of them love them and wear them constantly (even one who never ever wears dresses), and two of them have even gone and bought more. And as a bonus, it's also good as a maternity dress and for breastfeeding!
I just love this dress. I get so many compliments on it and I wear it almost every day. And now so do some of my friends!
For those of us who don't know where to start (like me), I also recommend checking out the wiki from r/malefashionadvice or r/femalefashionadvice.
I've tried optimizing and making "my personal" wardrobe and so on, but found that I ended up with one or two favorites pieces and disliked the rest. It's like a MLB slugger who hits a homer once a week and strikes out the rest of the time. I've had more success with just finding a "style tribe" I like and dressing like that. It's more of an MLB "singles and doubles", a consistently good-enough approach. I think people who wear streetwear look cool, and I like hanging out with them so don't mind strangers associating me with them. Now I wear mild variations of typical streetwear and find it much easier and more effective. Mild variations because I'm in my 30's and am wearing young people clothes, so have to display a sort of "grey beard" attitude about it. It's easier, because I can just look at r/streetwear's wiki for ideas. And it's more effective. As far as walking around, it seems like people prefer the principle of minimum surprise. People can now look at me, easily slot me into "he's wearing streetwear", and they can then judge me positively, according to how well I'm being creative within that tribe. It's easier to say, "ah, he's doing the Lindy Hop and he's doing it well" than to say, "he's doing... Something... And I can't tell whether he's doing it well or not." There's also a satisfying coherence about it. My entire wardrobe is now singing the same song, no matter what I choose to wear that day. I could perhaps have found this coherence through my own idiosyncratic style, but it wasn't worth the effort.
Note that if you have a little bit extra to spend, you can outsource some of the dimensions to experts. For example, those with a sense of style can offer you options you'd not have thought of yourself. The same applies to functionality and comfort (different experts though).
I've previously argued that nice clothes are good, actually. But this was an informal claim reflective of the fact that, all else equal, nice clothes are better. But, as elsewhere in life, all else is rarely equal. Choosing clothes and designing a wardrobe is a multivariable optimization problem, and it's a problem everyone but nudists are forced to solve because we must wear something. Most people tackle the problem via intuitions, heuristics & biases, and vibes. But we're aspiring rationalists. We can do better. We can wear optimal clothing, if only we bother to try.
But before we can do better, we must first not do worse. Therefore we must identify what optimal clothing is not. Optimal clothing is not a particular style. You cannot go to the Optimal Store and buy an Optimal Fit. Anyone claiming a particular style, brand, fabric, or article of clothing is optimal, full stop, is either lying, trying to sell you something, or confused about how optimization works. Optimal must always mean optimal for something, and in the case of clothing that something is mostly up to you.
Optimal clothing is also not about optimizing for one thing to the exclusion of everything else. If you only optimize for one thing the you're unlikely to be on the Pareto frontier of fashion. Optimal clothing is not about falling for easy traps (local maxima) like "just wear whatever's comfortable" or "wear what's popular on Instagram and TikTok". You're going to have to try a little harder than that if you want your clothes to be Pareto optimized for you.
So if that's what optimal clothing is not, what does count as optimal clothing? Clothing is optimal when you've optimized it across multiple dimensions at once to find the clothes that help you to live your best life. Importantly, you need clothes for how you actually live your life (or the life you aspire to have) in the body you have and the circumstances you find yourself in, not the life you imagine you could have if your body or the world were different.
Yet many people are tempted to optimize against their own delusions. I don't say this to be mean, but to point out that we're often confused about what's going on in our lives because it takes skill and practice to notice how we actually are. Most of us have some convenient lies we tell ourselves, like that we're taller or prettier or thinner or smarter than we really are, because they help us maintain an adequate baseline of psychological safety. But if we buy into our own lies we risk wearing things that don't look good on us, like jeans that fit too tight, colors that clash with our complexion, or styles that are out of place. Finding optimal clothing demands we face reality.
If we want to avoid these pitfalls we need better information than we can generate ourselves. Many well-dressed people rely heavily on the judgments of trusted friends who will tell them if something looks good on them or not. If you have a fashionable friend, ask them for their opinions and encourage them to be honest. When they give you their opinions, even if they bruise your ego, thank them for their honesty and update on what they say. If you don't have a fashionable friend, you can take your chances asking strangers on the internet, but be prepared to filter through a lot of noise from trolls.
Once you have an accurate sense of what's important to you and what your body looks like, you need to figure out what to optimize for within clothing-space. This means getting familiar with the dimensions along which garments vary with respect to how good they look on you and how well they fit your life. Here's roughly the dimensions I use to think about clothes:
Play around with what exact set of dimensions to help you identify the best clothes. Your needs are not exactly the same as everyone else's, and so you might need a finer-grained dimensional breakdown. For example, if you spend a lot of time outdoors, it might be useful to split functionality into subcategories like warmth, moisture wicking, packability, pockets, etc. Similarly, if you attend a lot of fashion-conscious social events, style and trendiness may require more nuanced evaluation. It's ultimately up to what dimensions best help you determine how well particular garments meet your needs.
Set of dimensions in hand, you can now start your search for optimal clothing. A good beginning is to go broad and get a sense of the possibility space. If you've thought about clothes your whole life this may not be necessary, but many people have never given clothes much thought and are surprisingly underaware of what clothes exist, especially when it comes to thinking about what clothes they might actually wear. Pay attention to what other people wear and make a mental note of what you think looks good. Go to the mall or a shopping district and spend time wandering through various stores. Don't go with a plan to buy anything: just look at things and notice what catches your eye. Over the course of 10 to 20 hours of such looking, you should start to get a sense of what might work for you.
Having developed a sense of what's possible, now it's time to find specific clothes for you. By now you should have some vague sense of what you want. Maybe you have a style in mind or you want to dress for certain occasions like work or dinner parties. For example, when I look for clothes I know I want them to fit in at the office, have conservative patterns and colors that will fit in at the Zen center, be relatively comfortable and allow me plenty of freedom of movement since I sometimes want to go on spontaneous hikes, and convey a vibe of quiet sophistication. I definitely don't always succeed in achieving this, but it's important to have ideas like this in mind to narrow your search.
Next I search for things I think I want, like "grey flannel shirt" or "straight-leg khaki pants". Google, Amazon, etc. returns lots of results. I also check the websites of brands I like to see if they carry pieces that might work for me. Almost everything I find is not what I want, but that's okay. I accept cookies and put ads to work for me. I get retargeted by companies trying to sell me things I might like, and then I check them out to see if I might like them. Eventually I find something that hits or gets pretty close to my desired location in clothing-space and buy it.
I realize not everyone wants to shop this way. Some of you hate ads or are unwilling to spend weeks waiting for serendipity to deliver you some ideal drip. Many of you would much rather take the direct approach. If so, you can follow the example of @Jacob Falkovich and putanumonit by creating a spreadsheet to score and rank clothes to determine what to buy. For example, you could make a column for each dimension you care about, score various potential purchases on each dimension, and then create a formula to do a weighted sum of the dimension scores based on how much each dimension matters to you. Then all you have to do is buy the clothes the score highest.
A word of warning, though, that this sort of spreadsheet approach can give you a false sense of objectivity. Numbers have a tendency to think there's more certainty than there really is. Remember that you made up the numbers! It will help you realize that clothing choices are highly subjective and personal because fashion is an iterated social game and what you value will change over time. You might start out thinking you don't care what others think, but then you dress nicer, start getting compliments, and realize you like looking nice enough to get compliments because the attention brings you joy. Or you think you're wearing something appropriate for work, but then fashion norms evolve and suddenly you're overdressed and perceived as out-of-touch. This can be annoying to folks hoping to "solve" clothing once and for all, but the only constant in this world is change, and you'll have to accept that even if you don't need to update your wardrobe every season you also can't expect to never need to make any updates after five years.
For myself, I'm still learning and developing my fashion sense. I can write this post because I've been guilty of getting clothes wrong for much of my life, and I'm maybe 30% along the way to mastering fashion. So if you see me in person, don't judge my advice or my clothing too harshly! I don't pretend to be an expert here: I only claim to know enough from other domains to know a multivariable optimization problem when I see one. My hope is that this post will help you see what it took me far too long to figure out, and you can start dressing better sooner and reaping the benefits of doing so.
Thanks to Justis for proofreading and feedback!