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Reversible and irreversible decisions (2018) (fs.blog)
110 points by durmonski on Oct 30, 2022 | hide | past | favorite | 39 comments



Decision reversibility is much overlooked in resilience engineering.

In a perfect world we'd have a kind of quantum uncertainty, where we forked reality into two streams, and maintained two options until one or the other proved a safe passage. Quoting from Digital Vegan;

  "Consider how the UK government let our drinking water reservoirs be
  sold off for property development, believing that advanced JIT (just
  in time) management technology, smart metering and so forth, would
  dispense with them. Then climate change came. Reservoirs are like
  power supply capacitors; they absorb as well as smooth out
  supply. Now in the UK we have housing estates built on flood plains.
  Rivers burst their banks with every downpour. Knocking down
  thousands of peoples' houses to regain reservoir capacity is much
  /harder/ than it was to sell the reservoirs to developers."
The transition from a reservoir to a housing estate looks like a net gain in "order" (entropy reduction) because it seems to create value, but considering the system as a whole (cost of losing infrastructure) it increases disorder.

Similarly our gushing project toward an "online cashless society" is playing with dangerous forces. It's a net destruction of wealth and order. It won't be cheap or quick to re-open shops, print and distribute cash, install ATMs and money handling facilities once the terrifying brittleness of a wholly digital economy becomes clear. Those imagining "Nothing can possibly go wrong with the all Bitcoin + Amazon society", haven't thought through the reality of what happens when tens of millions of people can't get food even though it's in a warehouse less than 100 miles from their house.


In 1970 in Ireland the banks were not functioning for up to 6 months at a time.

People worked around it.

https://www.ft.com/content/b8bc4a7a-20c3-11e5-ab0f-6bb9974f2...


Paywall.

I'd imagine 1970s Ireland was a much different place, with tons of paper money all over the place. In 2022 Ireland I haven't touched physical money in months. If Visa/MasterCard or my bank stopped working I'd be faaaahkt.


> I'd imagine 1970s Ireland was a much different place, with tons of paper money all over the place.

Exactly. Perhaps that was the GP commeners point. Banks, phones and internet connectivity are not necessary for survival of economic life given a sufficient circulation of stable physical currency.

Gold and barter don't count because of agreement/coordination problems.

Cash money is not like any other sort of imaginary money. It exists. Physically. In the world. It has physical stability.

It therefore acts a buffer, more like a flywheel maintaining momentum and providing strong resilience to back up more ethereal transactional instruments.

Modern cash is also a highly advanced technology, using state of the art mathematics and materials science.

Contactless, and debit cards are fine things, for those who want them, but without actual cash as a foundation they're a deadly trap.

I am uttery aghast that supposedly "clever" economists and technologists seem not to grasp this simplest of concepts.


Is it impossible to conceive or state the idea that these governmental actions are by design?


Why would an elite class of people or government want to collapse its own drinking water supply or financial system?


To control people through selective access to alternatives they've set up.


Headline of tomorrow, perhaps? Engineer Forced to Endure Twelve-Hour Scrum to Earn One Glass of Drinking Water in Gov't Pilot Scheme?


Because, if 'they' have a better system in place, that allows for greater control, they would want to move people to that instead. Just like how people are migrated from legacy systems to new ones.

The system we are meant to migrate to is ai-managed technocracy, with global governance (country governments will be adminstrative - they are that now tbh), central Bank digital currency (programmable, temporary credits - no cash) to allow tracking of everything, 'smart/spy' everything (phones, electricity, water) to allow for micro control of each individuals resource use.

'Saving the planet from climate change' is narrative that is in use to get turkeys voting for Christmas.


Unrelated, but inspired. A lot of people can't get food and other goods and services even though it's close to them or possible to provide them right now. And it works as intended and a few think that something went wrong.

It's rather the opposite: if there were no such people, it would be the scariest thing to people. Because how can communism go? Wrong answers only.


I guess russian leadership failed to consider this when they started their illegal imperial war to annex Ukraine. People of russia are almost irreversibly becoming the new 'nazis' of whose attrocities the kids will learn at school and of whom they will learn to despise for the rest of of their lives (while the earlier ones will be just another chapter in the history books that is read with the same enthusiasm that most study geopolitics behind WW1 currently).

This is not to suggest that the attrocities (at this point anyway) would be comparable, but that history is moving ahead.

Sorry about political angle, but due to my circumstances, I am very angry of what is happening, and I think these things cannot be repeated too many times.


What Russia is doing is horrible. War crimes and all. However I wouldn’t go so far as call them nazis, think it dampens that metaphor when it’s over used.

Russia feels NATO expansion is too close to their doorstep, he warned many times and this is the outcome.

Obviously not condoning it, and it’s many millions of lives displaced and tens of thousands lost. Generations will be effected.

Russia using the excuse of nazis in Ukraine, and the need to free the Ukrainian people is a tall tail. Though there is a small amount of truth, of actual nazis existing in some of the armed forces of Ukraine [0]. But by no means justifies what’s been done.

[0] https://www.nbcnews.com/think/opinion/ukraine-has-nazi-probl...


Oh, I see, the ones you call actual nazis, that would be the far-right hooligans with some tattoos or whatever that every single country in the world has? And the ones you wouldn't go as far as calling them nazis, that would be the completely innocent and harmless Russian dudes, invariably sent into Ukraine unawares, thinking it was just some military drills, or liberating people from evil banderites, or both at the same times apparently, the same completely harmless Russian dudes whose only teeny tiny little fault is that they for some reason can't help but commit genocide and other war crimes on a scale unseen in almost 80 years? Did I get that right?


> People of russia are almost irreversibly becoming the new 'nazis'

Is this really "new"? It's like you never heard about Stalinism, or even earlier: Leninism. Starting from 1920 war Bolsheviks tried to invade Poland; they starved millions in Ukraine in holodomor ( https://en.wikipedia.org/wiki/Holodomor ), they backstabbed Poland in 1939 only to "free" it, just like they "freed" rest of Eastern Europe. Later they crushed the Czech uprising in 1956 ( https://en.wikipedia.org/wiki/Prague_Spring )...

Not to mention millions who died in gulags.

It's like history 101. High school level stuff. You really never heard about it earlier?

The cycle is described in the old cartoon: https://twitter.com/theeconomist/status/447387748748759040


1956 is Hungarian Uprising, Prague Spring is 1968. They also did tons of vile stuff in the Baltics.

Russian imperialism goes much further back too, e.g. Partitions of Poland, colonization of Caucasus.

https://en.wikipedia.org/wiki/Partitions_of_Poland

Sadly, the way high school curricula are set up in many countries doesn't leave much time for 20th century history, so only a rough outline of post-war events is taught. As for more recent history, there has been almost no research (or even awareness) of Russian imperialism in Western academia until now (gee, wonder why)...


I haven't been completely unaware of those and other things. But vast majority of my history classes and bringing up focused on nazi germany being the sole responsible for everything WW2 and how we beat them. And then soviets being the commies and the enemy of the free world. And then the wall came down and everything was swell again.

So yes, I have been ignorant. Of which I am sorry. I may be late in the game, but let's put it out a loud: where are the russians living outside of russia that are protesting against russias war on Ukraine?


> where are the russians living outside of russia that are protesting against russias war on Ukraine?

https://en.wikipedia.org/wiki/Freedom_of_Russia_Legion


No, that's when you thought you were making a reversible decision but events played out in a way that made it irreversible.


Everything with US is reversible, just wait until next election... I really hope not too many people will die until then. Iran, Afghanistan, Lybia, Syria, Jemen... another pointless war. World needs something better!


Interesting framework. Perhaps one of the difficulties is that decision reversibility tends to lie on a spectrum between "reversible" and "irreversible", and sometimes it's hard to even know where on that spectrum it lies. Thus you end up having to figure out if a decision is "reversible", maybe even first needing to develop a decision framework in which to make such a determination. I think all of the truly difficult decisions I've made in work and life have been in this category.

Still, I appreciate this concept and I think it's better to have the mental model than not.


Yes. And when it comes to having multiple people and teams involved and starting work it may become costly to reverse an otherwise reversible decision.


Right, Bezos & this blog are framing the world as black & white when its really just lots of gray.

Many things that you could bucket into "type 2" decisions which are not one-way doors, effectively are. For example, orgs that tend to never go back and fix technical debt means everything is a one-way door.

Further, design decisions that require substantial and growing effort once you go through the door .. are effectively one-way doors as well.

Maybe ZIRP era over staffed FAANG could afford to build and rebuilt, have multiple competing redundant systems to see who wins, etc.. but most tech orgs just don't work that way.


You are framing it as black & white - I think miscategorising the article and Bezos. From the article:

  Decisions fall somewhere on the continuum from reversible to irreversible. You can tell where a decision lies on this spectrum by asking how much it would cost to undo. The higher the cost to undo, the more irreversible it is. The lower the cost, the more reversible it is.

  Bezos considers 70% certainty as the cut-off point where it is appropriate to make a decision. That means acting once we have 70% of the required information, instead of waiting longer.


I've used a similar model successfully in work situations where a decision is taking too long to make but is something that's reversible: pick a path, and put a note in the calendar to review that decision in a couple of weeks time.

If it turns out to be the wrong direction you can course correct then.

This really helps if not everyone on a team is convinced that it's the right decision: they can commit to it knowing that there will be a chance to change direction pretty soon if it turns out not to work.


Way back when I was a product manager the team would constantly want decisions in this or that. The reality was that a lot of these decisions really didn’t matter or didn’t matter much and could be course corrected. So the best course of action was to make some decision any decision. It was usually more informed than flipping a coin but it often didn’t need a lot of deep study either.


I've been learning a bit about distributed databases and of course AWS is a major user of such systems. The decision to do a mass migration from one distributed system to another, as an example, doesn't fit well with the kind of 'executive boardroom' mentality that this article is talking about.

The fundamental issue is more just taking the possiblity of error and failure of strategy into account. Hence, having a rollback strategy in place beforehand is wise. This post discusses a few basic recovery strategies plus more complicated ones:

https://aws.amazon.com/blogs/database/rolling-back-from-a-mi...

Bezos is likely well aware that the real world is always more complex than two simple choices, but that's too much information for a sales-confidence pitch to shareholders, I imagine.


Spatial data makes a lot of the 1 dimensional thinking more and more of a 20th century relic and even less of an opinion. "Those variables are unique to them" is an easy way to rationlize.

The culture divide make so many variables moot/invalid, since lifestyle, language and customs may not even associate with any of the variables (one-way/two-way doors for example).

As an individual, its easy to simplify. As someone trying to explain something, its easy to oversimplify, missing any/all of the details, experience and even the accumulated wisdom in basing the decision(s).

Reversible/irreversible is not usually a carrot on a stick. Even with health, detrimental/beneficial usually has more merit than any cost weighted variables (you can never buy your health back).

2=1+1 has worked just fine in traditional science for centuries. The (2) is usually unique though.

All that to say.... This article did nothing for me :)


I'm not sure if you really understood anything about what the article is actually trying to say and instead you got caught up on the types of examples it uses to help illustrate the framework for making decisions. Could you clarify why exactly the article did nothing for you?


"Make reversible decisions as soon as possible and make irreversible decisions as late as possible."

The summary sounded like a rash judgement.

Is A/B/C testing reversible, irreversable or a tool for clarity in goal making decisions? The article appeared to be 1 dimensional.

I was fortunate enough to have a website that crested into the top 800,000 websites years ago (a solo endeavor)... And backups made every decision reversible, if that was even a thing. I did have to commit to goals though and not once was anything irreversable.

The 1st world still bases decisions on the best data available.


I use this model a lot in life. I like to remember about this when in arguments with someone - once you say something that you later regret, it's very difficult to take it back.


I try to apply a similar mental model to new purchases. It can be tempting to weigh all the pros and cons of different products and find out a detailed list of all the possible alternatives.

But often you just have to try a product to find out if it works for you. In that case it can help to think about what risk there is in just buying something that seems ok.

If you can return it easily, or if it doesn't lose much value in using and you can sell it used for 90% of the new price then there's no real downside to just making a quick decision.

Detailed analysis is only really worth it for more 'irreversible' purchases where it's either a big hassle to undo the purchase (buying a house) or there's a large cost (cars lose value quickly).


What goods can you easily get 90% of the purchase price back?

In my experience, unless you’re spending a lot of time and effort selling, 50-60% is the best you can hope for most of the time.


The way I've framed it is the cost of making the decision should be in proportion to that decision turning out to be wrong.

It's extremely rare for decisions to be as binary as one-way or two-way, but there's always a point on the sliding scale of cost to change later.


This was a key lesson I learned creating and deploying aws services at Amazon.


Yeah, one-way door decisions VS two-way door decisions is how it's called in Amazon and while it's not a leadership principle in itself it is also ingrained in the culture.


We generally called them irreversible decisions and referred to the door analogy to explain it to folks unfamiliar to the culture.


This may work for business, where only money is at stake. But the hardest decisions in life are the ones where both options are irreversible. e.g. choosing to have an abortion or have a baby with someone you barely know. There's no reversible way to check the other side of either door.


I think using the word irreversible for both outcomes is entirely a matter of perspective. A person choosing to abort can still be a mother which would technically mean that option is highly reversible. Really just depends on what you consider the start and end states before and after either option is done.


There are a number of reasons a person might not be able to get pregnant again after an abortion. Abortion always carries a risk of sterilization. Other life factors such as age or health can also mean that a pregnancy can't happen again.




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