
How to choose? - fossuser
http://aeon.co/magazine/philosophy/is-the-most-rational-choice-the-random-one/
======
tikhonj
I regularly use randomness to make (small) decisions in my life. I look at my
watch and decide based on the last digit of the seconds. (Often, I just want
one bit—even or odd.)

Without this, I'm indecisive all too often, in the stupidest of places.
Choosing what to order at a restaurant, for example, used to be a bit of a
pain; now I just select a few acceptable choices and then decide randomly.
Similarly, it's also how I vary up my walk home: even, I take a left turn,
odd—a right.

It's a surprisingly useful little trick!

~~~
lotharbot
My parents used the last digit on a stopwatch to decide which of the kids got
to pick the radio station in the car and similarly trivial decisions. (If 0-9
couldn't be divided evenly among the kids present, leftover digits would
result in a re-roll.)

This trick takes away two types of pressure:

(1) trying to remember past decisions to be fair. Over a long enough period of
time, with a fair coin/die/watch, everyone will get about the same chances. Or
you'll walk all the routes about equally. Or you'll equally sample all of the
acceptable menu items.

(2) trying to justify which decision was made. There's no need for explaining
why Bob got to sit in the front seat, or why you ordered the chicken, or why
you walked on 3rd street instead of 2nd. There's no need for second-guessing
whether your decision accounted for all of the information and was really
reasoned through correctly.

I saw the true value of removing the "justify every decision" step when a
friend of mine was suffering from a severe mental illness that made it
difficult to make trivial decisions. The result of trying to justify every
decision: standing in the kitchen for several minutes because _" I want to
make a peanut butter sandwich, but I can't decide whether to get the bread or
the knife first."_ By creating an automatic process for making decisions that
are only slightly less trivial, we free ourselves to focus on the more
important things in life.

~~~
lutusp
> My parents used the last digit on a stopwatch to decide which of the kids
> got to pick the radio station in the car and similarly trivial decisions.
> (If 0-9 couldn't be divided evenly among the kids present, leftover digits
> would result in a re-roll.)

Easily solved by taking the [EDIT: seconds digits] modulo the number of
children, but I guess that might be difficult while driving.

EDIT: People, please try to think this through before posting an innumerate
reply.

~~~
baddox
You don't want to modulo. You want to multiply the last digit by the number of
children and divide by ten.

~~~
lutusp
> You don't want to modulo.

You haven't thought your reply through:

    
    
         n  n % 4
        ----------
         0  0
         1  1
         2  2
         3  3
         4  0
         5  1
         6  2
         7  3
         8  0
         9  1
        10  2
        11  3
        12  0
        13  1
        14  2
        15  3
    

> You want to multiply the last digit by the number of children and divide by
> ten.

That doesn't produce the result you think it does. Think a bit harder. If the
last digit is 20, and there are four children, the result is 4 * 20 / 10 = 8.
There is no eighth child.

~~~
baddox
Yeah, I was joking. The point is that either way you get a non-uniform
distribution for n children unless n divides 10. I think the part you are
misunderstanding in your responses is that the last _digit_ of a clock has
only ten options: 0 through 9. In the tables you have posted, children 0 and 1
each win 30% of the time, while children 2 and 3 each win only 20% of the
time.

With a single generation, you can't uniformly choose from a set of n options
with a random number generator that outputs m options, unless n divides m.

~~~
lutusp
> I think the part you are misunderstanding in your responses is that the last
> digit of a clock ...

Digits, not digit. I doubt this fact will limit the number of airheads who
downvote posts containing useful content.

~~~
baddox
Your last comment said

> If the last digit is 20, and there are four children, the result is 4 * 20 /
> 10 = 8.

Singular "digit."

~~~
lutusp
Do you actually think the point is to argue with people who actually know
things, like a lawyer instead of a scientist? Using a modulo operator is the
obvious solution to the original question, and cowardly anonymous downvotes
can't erase simple facts -- but they eventually make them have so little
contrast on the display that they become unreadable. What an achievement.

~~~
DanBC
Nearly everytime you mention downvotes: the reason is tone and attitude. I
don't know if you are aware just how much your tone influences the downvotes.

~~~
lutusp
> Nearly everytime you mention downvotes: the reason is tone and attitude.

Look -- I posted the obvious solution to a common problem. Everything else
depends on those who can't stand the unwelcome intrusion of simple, easily
stated facts.

My "attitude" is that this problem is easily solved, using simple arithmetic.
Imagine you're a scientist -- as such, do you object to a useful result
because of its source?

~~~
DanBC
I say this to help you, feel free to ignore it.

When you get a downvote, ignore it. It's probably accidental or meaningless
and these tend to self correct over a day.

When people downvote a bunch of your posts in a thread IGNORE THE DOWNVOTES.
Vindictive downvote sprees are usually corrected over the course of the day.
Mentioning the downvotes will usually prevent those corrective upvotes. Me
tioning the downvotes in the unpleasant way that you do will attract
downvotes.

You may wish to consider how you're presenting the information. If the first
table of numbers gets downvotes posting the same table again without more
information is going to get the same downvotes.

You could argue that it should not be this way, but it is.

~~~
lutusp
> You could argue that it should not be this way, but it is.

Indeed it is. State facts, back up what you say with evidence, get downvoted.
As certain as sunrise.

> If the first table of numbers gets downvotes posting the same table again
> without more information is going to get the same downvotes.

The alternative is to adopt the standards of religion instead of science. In
religion, if you start losing followers, you change the mythology. In science,
evidence is evidence, and how people feel about it has no standing.

> When you get a downvote, ignore it. It's probably accidental or meaningless
> ...

Easily proven false. My downvotes inevitably accompany anything I post that
has evidence and/or links to references. If I offer an uncorroborated opinion
or philosophical remark, however irrelevant or baseless, it's treated
neutrally. This is how science works -- you observe things dispassionately and
don't let yourself to be swayed by what people think is true.

~~~
TeMPOraL
Well, judging from your usual quality of comments (you're one of the users I
remember for good contributions in science threads) I think there's an
disagreement here that is not stated explicitly.

Do you disagree with any of the following statements, and if yes, where and
why?

\- original stopwatch solutions gives equal probability for any of the kid to
get picked

\- your modulo solution does not give equal probability for any of the kid to
get picked

\- you argue that the non-uniformness of your solution is not relevant in
practice, because number of kids is likely to be an order of magnitude smaller
than the readout from the stopwatch (i.e. last two digits)

~~~
lutusp
> Do you disagree with any of the following statements, and if yes, where and
> why?

Okay. I usually expect people to locate the errors in their own thinking, but
in this case, I'll make an exception. Here's one of the suggestions: "multiply
the last digit by the number of children and divide by ten". Let's see how
this works out:

    
    
         n  n * 7 / 10
         ----------------
         0  0
         1  0
         2  1
         3  2
         4  2
         5  3
         6  4
         7  4
         8  5
         9  6
    

The OP could have tested his suggestion before posting. I certainly would
have.

I'm going to avoid your straw men, with this exception:

> you argue that the non-uniformness of your solution is not relevant in
> practice

I never said that. I said that the error could be minimized. But consider my
test of the the alternative listed above. The error inherent with a relatively
small number of children and a relatively large original number, say, 0 - 59,
is a smaller error than the proposed alternative.

~~~
TeMPOraL
> _I 'm going to avoid your straw men_

Hey, I asked you three simple questions with pretty much boolean answers, in
order to try and clarify where exactly you end up disagreeing with everyone.
Please be charitable.

> _Here 's one of the suggestions: "multiply the last digit by the number of
> children and divide by ten"._

Hey, that one was clearly meant as a joke, and is not the suggestion I was
referring to. If something is a strawman here, this is. The one I asked about
is the "My parents used the last digit on a stopwatch to decide which of the
kids got to pick the radio station in the car and similarly trivial decisions.
(If 0-9 couldn't be divided evenly among the kids present, leftover digits
would result in a re-roll.)".

In light of that, could you provide the answers?

~~~
kaoD
I've been waiting for his answer impatiently. He's been active on other
threads but completely ignored your post. Says a lot.

~~~
TeMPOraL
Well, what can one do :(.

Anyway, I must say I found the technique I used above quite effective at
figuring out continous disagreements. You state some simple true/false
statements describing your assumptions and ask the other party to
agree/disagree and explain the points of disagreement. Apply recursively if
needed. Kind of a discussion equivalent of git bisect ;).

------
vecter
This seems relevant:

    
    
        In the days when Sussman was a novice, Minsky once
        came to him as he sat hacking at the PDP-6.
    
        "What are you doing?", asked Minsky.
        "I am training a randomly wired neural net to play Tic-tac-toe", Sussman replied.
        "Why is the net wired randomly?", asked Minsky.
        "I do not want it to have any preconceptions of how to play", Sussman said.
        
        Minsky then shut his eyes.
        
        "Why do you close your eyes?" Sussman asked his teacher.
        "So that the room will be empty."
    
        At that moment, Sussman was enlightened.
    

[0]
[http://en.wikipedia.org/wiki/Hacker_koan](http://en.wikipedia.org/wiki/Hacker_koan)

~~~
blinduck
I don't quite understand this. A person's preconceptions is the collection of
his previous knowledge about the subject. What does it mean to have random
preconceptions?

~~~
sanityinc
I believe the point is that the neural net will still have preconceptions --
but the random wiring just means you've chosen to not see what they are.

------
RK
My advisor in grad school once gave the following advice algorithm for making
a decision:

1\. Flip a coin.

2\. If the result of the coin flip makes you hesitate at all, you know that
was the choice you didn't really like anyway. Go with the other choice.

~~~
baddox
The problem is that in any decision difficult enough to make you resort to a
coin flip, most likely _either_ coin flip result will make you hesitate.

~~~
duncanawoods
I agree but I wouldn't take it too literally. The coin flip isn't binding but
it can be fascinatingly revealing about your own opinions.

I see it as a way to actualise the consequences of the choice and cut through
layers of intellectual abstraction. In some respects its a tool to let you
engage emotional thinking to help make better decisions. On the flip, it can
suddenly trigger a feeling of loss and regret. Our fundamental beliefs can be
strangely out of reach when we think too hard.

A similar tool is just explaining your decision to another. I can get a flush
of emotion e.g. embarrassment or shame, that you don't get when you just
cogitate alone. Pretty useful for tough design decisions e.g. midway through
explaining a particularly clever idea I find myself apologising... its time to
rethink things!

------
kissickas
The author never comes back to it, but the Greeks used a lottery to choose
some of their politicians in order to mitigate corruption:

[https://en.wikipedia.org/wiki/Athenian_democracy#Selection_b...](https://en.wikipedia.org/wiki/Athenian_democracy#Selection_by_lot_.28allotment.29)

I discovered this the other day when trying to find out what "drawing lots"
actually meant in the Bible, another form of letting chance decide things.
Apparently we don't know exactly what people were using back then.

~~~
blue1
The Republic of Venice developed that idea to a system of great complexity for
electing the Doge, that included copious injections of randomness. There is an
interesting analysis of this protocol in a paper by HP laboratories, available
here (pdf):
[http://www.hpl.hp.com/techreports/2007/HPL-2007-28R1.pdf](http://www.hpl.hp.com/techreports/2007/HPL-2007-28R1.pdf)

------
tbrownaw
If you know more than nothing, the best choice is often still random -- just
with different weights applied to the various options, which I hear can be
calculated with something called game theory.

~~~
afafsd
Under what circumstances is that the case?

Let's suppose, for instance, that two roads diverge in a yellow wood and you
have reliable information that road A is the correct path with 90% probability
and road B is the correct path with 10% probability. The normal person takes
road A and will be right 90% of the time.

On the other hand, if you try to be probabilistic about it and follow road B
with 10% probability to reflect its 10% probability of being the right road,
then your chances of picking the right road are 0.9 _0.9 + 0.1_ 0.1 = 82%.

Maybe there's a more complex situation where the weighted random decision
making is a better idea, but I'm not seeing it right now.

~~~
Sambdala
Since my background is poker, I'll use an (overly simplified) example from
there.

There are situations where you want to manipulate your range (set of hands) in
a given spot so that your actions make up a certain distribution.

For example, if you want your range to be made up of 30% bluffs, you can
figure out how often you get to that spot with a bluff and how often you get
to that spot with a strong hand. Since you're always continuing with the
strong hand, you can then know what percentage of the time you need to
continue to bluff in order to accomplish this. Since it doesn't matter which
of those hands you choose to bluff with, it generally makes sense to use
randomness to decide in the moment.

~~~
TeMPOraL
I don't play poker, but from what I understand, the reason for including
randomness in your decision is to throw your opponents off. I.e. You're
playing against people who try to predict your behavior, so you throw in a
random component to make it harder for them.

In decisions not involving active adversaries, deciding at random doesn't give
you anything over a deterministic solution.

~~~
antimagic
Nearly, but just to nitpick, you're not including randomness, you're actively
making a choice to make the resulting pattern difficult to distinguish from
randomness. So, sometimes you raise by a large amount because you have a
strong hand. You don't want other players to be identify that you have a
strong hand by the fact that you just offered a large raise, so you have to
also bluff sometimes, raising when you really don't have the cards. Your
actions are not random, but they are _perceived_ as random by the other
players.

------
dreamfactory2
Isn't this covered by Cynefin -
[http://en.wikipedia.org/wiki/Cynefin](http://en.wikipedia.org/wiki/Cynefin)?
Action first in the chaotic quadrant corresponds to making a fast decision in
the face of unpredictability.

~~~
pontifier
I love finding new ways of thinking and solving problems. Thanks for
referencing this.

~~~
dreamfactory2
If you are in software dev worth reading
[http://lizkeogh.com/2012/03/11/cynefin-for-
devs/](http://lizkeogh.com/2012/03/11/cynefin-for-devs/)

------
shire
I think I'm very indecisive, I have hard time ordering stuff at restaurants
without holding up lines. I need to find a method of deciding soon. I'll try
the coin trick.

~~~
gglitch
I have that problem too. I usually narrow it down to two or three options and
ask the server/cashier what I want. About 80% of the time I go with whatever
s/he says; other times, simply hearing his/her recommendation makes me realize
what my actual preference is.

------
Gmo
Makes me think of this book (which turns out pretty badly) :

[http://en.wikipedia.org/wiki/The_Dice_Man](http://en.wikipedia.org/wiki/The_Dice_Man)

~~~
slazaro
I recommend this book. It's really entertaining and thought provoking. I
remember carrying a die everywhere a few weeks after reading this book, in
order to add some randomness to my decisions. Silly, but fun!

------
dredmorbius
The fairness and justification elements alone are fascinating.

This also brings to mind strongly Suzanne Vega's "Predictions."

------
dkarapetyan
Anyone see an analogy here with startups? I do.

~~~
camillomiller
The difference is that investors would like us to believe they follow a
rational path to decide where to invest :D

~~~
mareofnight
Or in the case of VC firms, would like _their_ investors to believe this.

