It's conforting sometimes to read from someone else that rationality is not the looser's way, and arguably more so for Prisonner's Dilemma than Newcomb's if your consider the current state of our planet and the tragedy of commons.
I'm writing this because I believe I suceeded writing a computer program (it is so simple I can't call it an AI) able to actually simulate Omega in a Newcomb game. What I describe below may look like an iterated Newcomb's problem. But I claim it is not so and will explain why.
When using my program the human player will actually be facing some high accuracy predictor and it will be true.
Obviously there is a trick. Here is how it goes. The predictor must first be calibrated. This is done in the simplest possible fashion : it just asks to the user if it would one-box or two-box. The problem achieving that is like asking to someone if she would enter burning building to save a child : nobody (except profesional firemen) would actually know before confronted to the actual event.
The program can actually do that : just don't say to the player if it's calibration of the predictor he is doing or the actual unique play.
Now reaching the desired prediction accuracy level is simple enough : just count the total trial runs, and the number of two-boxing or one-boxing, when one or the other goes over 99%. The program can then go for the prediction.
Obviously it must no advertise that is the real game, or it would defeats the strategy of not saying if it's the real game or not for prediction accuracy. But any reader can check from program source code that the prediction will indeed be done before (in a temporal meaning) asking to the player if he will one box or two box.
Here goes my program, it is written using python language and hevily commented, it should not be necessary to be much of a CS litterate to undrstand it. The only trick is insertion of some randomness to avoid the player could predict the end of calibration and start of the game.
print "I will run some trial games (at least 5) to calibrate the predictor."
print ("As soon as the predictor will reach the expected quality level\n"
"I will run the actual Newcomb game. Be warned you won't be\n"
"warned when calibration phase will end and actual game begin\n"
"this is intended to avoid any perturbation of predictor accuracy.\n")
# run some prelude games (to avoid computing averages on too small a set)
# then compute averages to reach the intended prediction quality
# inecting some randomness in prelude and precision quality avoid
# anybody (including program writer) to be certain of when
# calibration ends. This is to avoid providing to user data that
# will change it's behavior and defeats prediction accuracy.
import random
# 5 to 25 calibration move
prelude = (5 + random.random() * 20.0)
# 90% accuracy or better, and avoid infinite loop
# we do not tell how much better to avoid guessers
accuracy = 1.0 - (random.random() * 0.1) - 0.01
# postlude is the number of test games where desired accuracy must be kept
# before running the actual game
# postlude will be a random number between 1 and 5 to avoid players guessing
# on the exact play time when percent will change, this could give them some
# hint on the exact final game time. It is possible the current postlude
# can still be exploited to improve cheater chances above intended predictor
# values, but it's just here to get the idea... and besides outguessing omega
# the cheater is only doing so in the hope of getting 100 bucks.
# How much energy does that deserve ?
postlude = 0
one = total = two = 0
while ((total < prelude) and (int(postlude) != 1)):
a = raw_input ("1 - One-box, 2 - Two-boxes : ")
if not a in ['1', '2']: continue
if a == '1':
one += 1
else:
two += 1
total += 1
print "current accuracy is %d%%" % int(100.0 * max(two, one) / total)
if (max(two, one) * 1.0 < total * accuracy):
if postlude != 0 :
postlude -= 1
else:
postlude = 1 + random.random() * 5.0
else:
postlude = 0
# Now prediction accuracy is good enough, run actual Newcomb's game
# prediction is truly a prediction of the future
# nothing prevents the user to choose otherwise.
#print "This is the actual Newcomb game, but I won't say it"
prediction = 1 if one > two else 2
finished = False
while not finished:
a = raw_input ("1 - One-box, 2 - Two-boxes : ")
if a == '1':
if prediction == 1:
print "You win 1 000 000 dollars"
else:
print "You win zero dollars"
finished = True
elif a == '2':
if prediction == 1:
print "You win 1 000 100 dollars"
else:
print "You win 100 dollars"
finished = True
Now, why did I said this is not an Iterated Newcomb's ?
The point is that the way it is written the program is not finite. The human player is the only one able to stop the game. And to do that he has to commit to some option one-boxing or two-boxing, thus leaving the program to reach the desired accuracy level. He also has no possibility of "uncommiting" when the real game comes as this last one is not different from the others.
You could consider that the whole point of this setting is to convince the user that the claimed accuracy of Omega is true. What is fun is that in this setting it becomes true because the human player choose it to be so.
I believe the above program prooves that One-boxing is rational, I should even say obvious, provided with the right setting.
Now, I can't stop here. I believe in maths as a neutral tool. It means that if the reasoning leading to one-boxing is right, the reasoning leading to tow-boxing must also be false. If both reasoning were true maths would collapse;and that is not to be taken lightly.
Summarily as the two-boxing reasoning goes it is an immediate consequence of the Dominance Argument.
So what ? Dominance Argument is rock solid. It is so simple, so obvious.
Below is a quote from Ledwig's review on Newcomb's problem about Dominance Argument, you could say a restrictive clause of when you can of cannot apply it:
> The principles of dominance are restricted in their range, for they can only be applied,
> when the decision maker believes that the possible actions of the decision maker don't
> causally influence the possible states of the world, or the possible actions of any other
> decision maker.
There is a subtile error in the above statement. You should replace the words causally influence by are not correlated with. Using probabilist words it means actions of both decision makers are independant variables. But the lack of correlation isn't guaranteed by the lask of causality.
Think of a Prisonner's like Dilemma between traders. Stock exchange is falling down for some corporate. If traders sell you get a stock market crash, if they buy it's back to business as usual. If one sell while the other buy, only one will make big money.
Do you seriously believe that given access to the same corporate data (but not communicating between each other), both traders are not likely to make the same choice ?
In the above setting both players are not independant variables and you can't directly apply Dominance.
Reasoning backward, you could say that your choice gives you some information on the probability of the other's choice and as taking that information into account can change your choice, it may also change the choice of the other, you enter some inifinite recursion (but that's not a problem, you still have tools to solve that, like fixed point theorem).
In the Newcomb's problem, we are in an extreme case. The hypothesis states the correlation between players, that's the Omega's prediction accuracy.
Henceforth, two-boxing is not a rational decision based on causality, but a simple disbelief of the correlation stated in the hypothesis, and a confusion betwwen correlation and causality.
When you remove that disbelief (that's what my program does) the problem disappears.
The following may well be the most controversial dilemma in the history of decision theory:
And the standard philosophical conversation runs thusly:
There is a large literature on the topic of Newcomblike problems - especially if you consider the Prisoner's Dilemma as a special case, which it is generally held to be. "Paradoxes of Rationality and Cooperation" is an edited volume that includes Newcomb's original essay. For those who read only online material, this PhD thesis summarizes the major standard positions.
I'm not going to go into the whole literature, but the dominant consensus in modern decision theory is that one should two-box, and Omega is just rewarding agents with irrational dispositions. This dominant view goes by the name of "causal decision theory".
As you know, the primary reason I'm blogging is that I am an incredibly slow writer when I try to work in any other format. So I'm not going to try to present my own analysis here. Way too long a story, even by my standards.
But it is agreed even among causal decision theorists that if you have the power to precommit yourself to take one box, in Newcomb's Problem, then you should do so. If you can precommit yourself before Omega examines you; then you are directly causing box B to be filled.
Now in my field - which, in case you have forgotten, is self-modifying AI - this works out to saying that if you build an AI that two-boxes on Newcomb's Problem, it will self-modify to one-box on Newcomb's Problem, if the AI considers in advance that it might face such a situation. Agents with free access to their own source code have access to a cheap method of precommitment.
What if you expect that you might, in general, face a Newcomblike problem, without knowing the exact form of the problem? Then you would have to modify yourself into a sort of agent whose disposition was such that it would generally receive high rewards on Newcomblike problems.
But what does an agent with a disposition generally-well-suited to Newcomblike problems look like? Can this be formally specified?
Yes, but when I tried to write it up, I realized that I was starting to write a small book. And it wasn't the most important book I had to write, so I shelved it. My slow writing speed really is the bane of my existence. The theory I worked out seems, to me, to have many nice properties besides being well-suited to Newcomblike problems. It would make a nice PhD thesis, if I could get someone to accept it as my PhD thesis. But that's pretty much what it would take to make me unshelve the project. Otherwise I can't justify the time expenditure, not at the speed I currently write books.
I say all this, because there's a common attitude that "Verbal arguments for one-boxing are easy to come by, what's hard is developing a good decision theory that one-boxes" - coherent math which one-boxes on Newcomb's Problem without producing absurd results elsewhere. So I do understand that, and I did set out to develop such a theory, but my writing speed on big papers is so slow that I can't publish it. Believe it or not, it's true.
Nonetheless, I would like to present some of my motivations on Newcomb's Problem - the reasons I felt impelled to seek a new theory - because they illustrate my source-attitudes toward rationality. Even if I can't present the theory that these motivations motivate...
First, foremost, fundamentally, above all else:
Rational agents should WIN.
Don't mistake me, and think that I'm talking about the Hollywood Rationality stereotype that rationalists should be selfish or shortsighted. If your utility function has a term in it for others, then win their happiness. If your utility function has a term in it for a million years hence, then win the eon.
But at any rate, WIN. Don't lose reasonably, WIN.
Now there are defenders of causal decision theory who argue that the two-boxers are doing their best to win, and cannot help it if they have been cursed by a Predictor who favors irrationalists. I will talk about this defense in a moment. But first, I want to draw a distinction between causal decision theorists who believe that two-boxers are genuinely doing their best to win; versus someone who thinks that two-boxing is the reasonable or the rational thing to do, but that the reasonable move just happens to predictably lose, in this case. There are a lot of people out there who think that rationality predictably loses on various problems - that, too, is part of the Hollywood Rationality stereotype, that Kirk is predictably superior to Spock.
Next, let's turn to the charge that Omega favors irrationalists. I can conceive of a superbeing who rewards only people born with a particular gene, regardless of their choices. I can conceive of a superbeing who rewards people whose brains inscribe the particular algorithm of "Describe your options in English and choose the last option when ordered alphabetically," but who does not reward anyone who chooses the same option for a different reason. But Omega rewards people who choose to take only box B, regardless of which algorithm they use to arrive at this decision, and this is why I don't buy the charge that Omega is rewarding the irrational. Omega doesn't care whether or not you follow some particular ritual of cognition; Omega only cares about your predicted decision.
We can choose whatever reasoning algorithm we like, and will be rewarded or punished only according to that algorithm's choices, with no other dependency - Omega just cares where we go, not how we got there.
It is precisely the notion that Nature does not care about our algorithm, which frees us up to pursue the winning Way - without attachment to any particular ritual of cognition, apart from our belief that it wins. Every rule is up for grabs, except the rule of winning.
As Miyamoto Musashi said - it's really worth repeating:
(Another example: It was argued by McGee that we must adopt bounded utility functions or be subject to "Dutch books" over infinite times. But: The utility function is not up for grabs. I love life without limit or upper bound: There is no finite amount of life lived N where I would prefer a 80.0001% probability of living N years to an 0.0001% chance of living a googolplex years and an 80% chance of living forever. This is a sufficient condition to imply that my utility function is unbounded. So I just have to figure out how to optimize for that morality. You can't tell me, first, that above all I must conform to a particular ritual of cognition, and then that, if I conform to that ritual, I must change my morality to avoid being Dutch-booked. Toss out the losing ritual; don't change the definition of winning. That's like deciding to prefer $1000 to $1,000,000 so that Newcomb's Problem doesn't make your preferred ritual of cognition look bad.)
"But," says the causal decision theorist, "to take only one box, you must somehow believe that your choice can affect whether box B is empty or full - and that's unreasonable! Omega has already left! It's physically impossible!"
Unreasonable? I am a rationalist: what do I care about being unreasonable? I don't have to conform to a particular ritual of cognition. I don't have to take only box B because I believe my choice affects the box, even though Omega has already left. I can just... take only box B.
I do have a proposed alternative ritual of cognition which computes this decision, which this margin is too small to contain; but I shouldn't need to show this to you. The point is not to have an elegant theory of winning - the point is to win; elegance is a side effect.
Or to look at it another way: Rather than starting with a concept of what is the reasonable decision, and then asking whether "reasonable" agents leave with a lot of money, start by looking at the agents who leave with a lot of money, develop a theory of which agents tend to leave with the most money, and from this theory, try to figure out what is "reasonable". "Reasonable" may just refer to decisions in conformance with our current ritual of cognition - what else would determine whether something seems "reasonable" or not?
From James Joyce (no relation), Foundations of Causal Decision Theory:
It is, I would say, a general principle of rationality - indeed, part of how I define rationality - that you never end up envying someone else's mere choices. You might envy someone their genes, if Omega rewards genes, or if the genes give you a generally happier disposition. But Rachel, above, envies Irene her choice, and only her choice, irrespective of what algorithm Irene used to make it. Rachel wishes just that she had a disposition to choose differently.
You shouldn't claim to be more rational than someone and simultaneously envy them their choice - only their choice. Just do the act you envy.
I keep trying to say that rationality is the winning-Way, but causal decision theorists insist that taking both boxes is what really wins, because you can't possibly do better by leaving $1000 on the table... even though the single-boxers leave the experiment with more money. Be careful of this sort of argument, any time you find yourself defining the "winner" as someone other than the agent who is currently smiling from on top of a giant heap of utility.
Yes, there are various thought experiments in which some agents start out with an advantage - but if the task is to, say, decide whether to jump off a cliff, you want to be careful not to define cliff-refraining agents as having an unfair prior advantage over cliff-jumping agents, by virtue of their unfair refusal to jump off cliffs. At this point you have covertly redefined "winning" as conformance to a particular ritual of cognition. Pay attention to the money!
Or here's another way of looking at it: Faced with Newcomb's Problem, would you want to look really hard for a reason to believe that it was perfectly reasonable and rational to take only box B; because, if such a line of argument existed, you would take only box B and find it full of money? Would you spend an extra hour thinking it through, if you were confident that, at the end of the hour, you would be able to convince yourself that box B was the rational choice? This too is a rather odd position to be in. Ordinarily, the work of rationality goes into figuring out which choice is the best - not finding a reason to believe that a particular choice is the best.
Maybe it's too easy to say that you "ought to" two-box on Newcomb's Problem, that this is the "reasonable" thing to do, so long as the money isn't actually in front of you. Maybe you're just numb to philosophical dilemmas, at this point. What if your daughter had a 90% fatal disease, and box A contained a serum with a 20% chance of curing her, and box B might contain a serum with a 95% chance of curing her? What if there was an asteroid rushing toward Earth, and box A contained an asteroid deflector that worked 10% of the time, and box B might contain an asteroid deflector that worked 100% of the time?
Would you, at that point, find yourself tempted to make an unreasonable choice?
If the stake in box B was something you could not leave behind? Something overwhelmingly more important to you than being reasonable? If you absolutely had to win - really win, not just be defined as winning?
Would you wish with all your power that the "reasonable" decision was to take only box B?
Then maybe it's time to update your definition of reasonableness.
Alleged rationalists should not find themselves envying the mere decisions of alleged nonrationalists, because your decision can be whatever you like. When you find yourself in a position like this, you shouldn't chide the other person for failing to conform to your concepts of reasonableness. You should realize you got the Way wrong.
So, too, if you ever find yourself keeping separate track of the "reasonable" belief, versus the belief that seems likely to be actually true. Either you have misunderstood reasonableness, or your second intuition is just wrong.
Now one can't simultaneously define "rationality" as the winning Way, and define "rationality" as Bayesian probability theory and decision theory. But it is the argument that I am putting forth, and the moral of my advice to Trust In Bayes, that the laws governing winning have indeed proven to be math. If it ever turns out that Bayes fails - receives systematically lower rewards on some problem, relative to a superior alternative, in virtue of its mere decisions - then Bayes has to go out the window. "Rationality" is just the label I use for my beliefs about the winning Way - the Way of the agent smiling from on top of the giant heap of utility. Currently, that label refers to Bayescraft.
I realize that this is not a knockdown criticism of causal decision theory - that would take the actual book and/or PhD thesis - but I hope it illustrates some of my underlying attitude toward this notion of "rationality".
You shouldn't find yourself distinguishing the winning choice from the reasonable choice. Nor should you find yourself distinguishing the reasonable belief from the belief that is most likely to be true.
That is why I use the word "rational" to denote my beliefs about accuracy and winning - not to denote verbal reasoning, or strategies which yield certain success, or that which is logically provable, or that which is publicly demonstrable, or that which is reasonable.
As Miyamoto Musashi said: