Jamie on Software

This is the blog of Jamie Rumbelow: a software engineer, writer and philosophy graduate who lives in London.

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months: November 2022 October 2022 September 2022 August 2022 July 2022 June 2022 May 2022 April 2022 March 2022 January 2022 May 2021 February 2020 January 2020 December 2019


How to think about recommendations

I make a lot of recommendations for restaurants. I also receive a fair few.

Unless the facts change from out under my feet – one day I’ll tell you a story about The Marksman – I think my recommendations are generally pretty good. But I would, wouldn’t I? Unless I don’t like you, I’m not going to recommend things I don’t think are good recommendations.

It’s very important to be careful when recommending. If you eat out often, say ~3 times / week, you can expect to have ~9,300 meals over a 60-year adulthood of eating. That isn’t many meals! I read roughly a book per week. That’s ~3,120 books in the same adulthood. That isn’t many books! So each meal and each book has to count. & many people eat out many fewer times per month and read much less. Centrally: you should respect the time and money that people will spend based on your recommendations.

It’s also easier to recommend things in the indirect-objectless sense, as I do in the restaurant list above. But recommendations are often recommendations to somebody, in some context, for some purpose.

In these cases, how should we tell which recommendations to listen to, and which to ignore? How reliable is the average recommendation? How can you reliably make good recommendations to others?

Off the top of my head, there are obvious heuristics we can use:

  • Prior experience of the recommender’s recommendations. Have you been to restaurants with this person before? Did you like the last movie she recommended?
  • The recommender’s knowledge of the subject matter. Is he an expert? Are they at least an enthusiastic amateur? Are you confident they know a lot about this?
  • The recommender’s knowledge of the recommendee’s tastes. Does this person know you? Do you have confidence in her model of your preferences? Does he buy you good novels at Christmas?
  • Consensus amongst more than one recommender. Have you heard from multiple people that this restaurant is good? Have each of them been consistent in their reasons for recommending it, or have the different reasons been intriguing and appealing?

These each seem non-controversially true: if these conditions are met, it seems more likely that you’ll get a good recommendation. But it’s not at all obvious to me that you’ll reliably (i.e. >50% of the time) get a good recommendation.

For one thing, the facts can change from out under the feet of the recommender. In a large city like London, you’re not likely to revisit the same restaurant more than a few times a month (unless it’s provenly reliable and local). Staff turns over, the great old chef moves to her new place, your friend goes on a busy night, has horrible service, and it’s game over.

For another, it’s only semi-plausible that good taste clusters. So if the recommender’s taste in novels is good, that doesn’t on the face of it seem to suggest his taste in restaurants will necessarily be good; or art, or music, or whatever else. Some people seem blessed with good taste across the board, but that’s far from true universally.

For a third – and this is my central point here – contexts which involve taste exhibit huge interpersonal variation no matter how persuasive the a priori justification happens to be.

So what are some things we can do to ensure we receive better recommendations, and can filter out the bad ones that slip through?

  • Surround yourself by people with good taste. This seems like an easy one, but something I think not enough people act on meaningfully. It’s worth selecting good taste into your friendship group, not just because the quality of the recommendations you’ll receive will increase, but because you’ll develop a better appreciation for what sorts of people are the sorts of people who make good recommendations, which of course generalises.
  • Cultivate better taste yourself; learn more. Another easy one too easily forgotten. Do you reflect on your aesthetic experiences, note what you enjoyed and what you didn’t? Do you move outside of your comfort zone frequently, and take the hits (so your recommendees don’t have to?) Do you make an active and regular effort to learn more?1
  • Select for order-of-magnitude differences. You should aim to find recommenders who have at least an order-of-magnitude more experience than you, and try to tailor your recommendations to people with at least an order-of-magnitude less. There’s enough noise so that the marginal next % of exposure seems much less important. I wouldn’t, for instance, trust the judgement of somebody who had been to strictly one more opera than me. (This perhaps isn’t the case if I’ve never been to an opera.) Another reason why a little learning is a dangerous thing.
  • Go wide then deep then wide again. A good way to think about taste is effective pattern-matching. For this you first need a broad range of knowledge to anchor novel experiences, and then enough depth of understanding to discriminate between the great and merely good. But it’s important to back out of the rabbit hole and dig yourself another one. Eat fifteen different cuisines, then pick a few and learn the regional variances within them, then eat fifteen more.2
  • Consider the incentives. Tyler Cowen’s famous piece on restaurant recommendations makes this point well. If a restaurant is full of good-looking people, it will attract more people, holding fixed the quality of the food, which reduces the incentive for the restaurant to care about the food as much. (The restaurant, in effect, stops competing on quality of food and thus stops caring about it.) These sorts of incentives are everywhere, and it’s both fun and useful to be a little cynical and consider how they might affect your experience, and the recommendations you receive and make on the basis of it.

Two final points to consider. Firstly, perhaps try to elicit and make anti-recommendations rather than positive recommendations. It can often be more helpful to know where to avoid rather than where to go. This seems a little counterintuitive, since we’re optimising for the positive case – i.e. the case in which we in fact do go to the restaurant – but it’s useful because it provides useful information and still ‘frees up’ the higher end of the recommendation spectrum to float more independently. Similar concerns apply to groups of positive recommendations (“eat in Shoreditch”, “read novels from feminist authors in the 1920s”). You can then use your good taste to narrow it down further.

Finally, and most importantly, try to keep an open mind, and give others as many opportunities to be open-minded as possible. (If that means hiding certain things from your recommendees, so be it.) This can be very high-leverage, because the best sort of recommendation (at least in an information-theoretic sense) is the recommendation somebody is unlikely to receive from anybody else. For instance, many people miss out on amazing food because they dislike the idea of offal, while at the same time are fine with a chicken liver pâté. It’s not that they won’t like offal, it’s that they’re unlikely to follow a recommendation that mentions it, and therefore people are unlikely to make these recommendations in the first place. Sometimes it takes a bit of energy to get past the inertial resistance.

My mother hates the idea of lardo, but couldn’t stop eating the lardo-fried rice at Smoking Goat. I may have forgotten to tell her what it was.

  1. There are some interesting questions about the dynamics of taste. Tastes appear to ossify as you get older, which is a shame since your knowledge accumulates (generally) monotonically. I need to think about this more. 

  2. This approach also helps counter Gell-Mann amnesia, because you interlace the development of expertise with novelty and force yourself to consider whether and in which ways the experiences cross-cut. 

9:31am. January 3, 2022.

The trade-offs are worth it

I’m very prone to greener-grass thinking.

Sometimes it’s important to acknowledge that the grass is greener, because, well it is. Sometimes you’re not in the best possible timeline, and bringing it to your own attention is the first step toward changing it.

But it’s often unhelpful, too, and can trap you into a cycle of distraction and dissatisfaction. You change something, because the grass over there is greener, and you reinforce the preferences you have for novelty. The less you develop the ability to stick with something, focus, persevere, the more difficult it becomes the next time you must.

The more vulnerable you become to your own whims.

The more often you throw away something valuable, because you’re suffering under some sort of novelty bias and what appears to be objectively better is simply fresher.

So it can be useful to reframe how you view your current situation. When I regret some decision because the alternative looks easier, or if I suspect I have made a mistake, I can find solace in the knowledge that:

  1. It can be easy to forget you’re making trade-offs explicitly and knowingly;
  2. and, the tradeoffs are generally worth it.

The beginning of anything requires a first step. A new job, a new purchase, a new skill or hobby, a new relationship. If you’re a thoughtful and goal-oriented person, you will consider whether this the right step for you. Something that might appear to be obvious at the time might be a mistake later, and you know this, so you take your time, weigh up your options. Consider the pros and cons and decide to act.

The next day, you’re in the honeymoon phase. The cons are irrelevant. The pros are even better than you expected. You enjoy the present. You look forward to the future with anticipation, with giddiness, with glee.

Some days later, the pros and cons look evenly balanced. You’re less interested than you once were, but stasis is a powerful force, so you do nothing about it.

Some days further, the cons are now what is salient. What began as small pet peeves or niggling doubts have blossomed. The cons are so overwhelming, so frustrating, that you cannot imagine why you could ever have thought the pros might outweigh them (or, hell, even counterbalance them!)

What seemed like a good idea now looks like a set of inappropriate, naïve preferences borne from the brain of somebody who knew less than what you do now.

But here’s the thing. You made those tradeoffs. You considered the pros, you considered the cons.

You might have missed some of the cons initially; not everybody gets it right first time. But this also applies to the pros. Are there not things about your role, your club, your partner, your commitment, whatever it is, that are unexpectedly pleasant, as well as unexpectedly not-so?

If it appears not, then consider this: even if you were able to predict everything a priori, do you think you’d be weighing the cons and pros appropriately after the cons have become so aggravating that you felt the need to reweigh them in the first place?

People only really reflect on whether their decisions were correct when they have reason to suspect that they weren’t.

People don’t look to upend the boat when they’re enjoying the journey.

So your re-evaluation may be happening from a place of more intimate knowledge, but it’s also happening from a place of discomfort.

There are definitely times when you should re-evaluate. When you are being harmed. When you have good reason to suspect you misjudged it all initially. Or when your preferences have changed significantly since then.

But there are lots of times when you shouldn’t. When, were you to reflect in a pro-dominant phase, you’d conclude quite differently.

The grass is always greener, Jamie.

The tradeoffs are usually worth it.