1

The Prisoner’s Dilemma: An (Un)Natural Experiment

from Nazi Germany

Wayne Geerling (Pennsylvania State University) *

Gary Magee (Monash University) +

Robert Brooks (Monash University) #

Abstract

This study examines a real-world, one-shot, high-stakes

prisoner’s dilemma, very similar to the story often related in

textbooks. The ‘prisoners’ were individuals, aged between 15

and 62, charged with high treason in Nazi Germany between

1933 and 1945. They faced a choice between cooperation and

defection. We find that even in such extreme settings

significant cooperation rates remain, though at rates lower

than in games undertaken in controlled circumstances or on

game shows, suggesting that the size of the stake does

influence social preferences. We also find evidence that age,

education, affiliations and a sense of community also play

roles.

DRAFT: NOT to be quoted from or cited without authors’ permission

* Department of Economics, Pennsylvania State University, 306 Kern Building, University Park,

PA 16802, UNITED STATES OF AMERICA. Tel: +1 8148673300. Email: wag11@psu.edu + Department of Economics, Monash University and Department of Economics and

Econometrics, University of Johannesburg. Faculty of Business and Economics, Building S, Level 9, Monash University, PO Box 197, Caulfield East, Vic 3145, AUSTRALIA. Tel: +61 399031307. Email: gary.magee@monash.edu # Department of Econometrics and Business Statistics, Building S, Level 9, Monash University,

PO Box 197, Caulfield East, Vic 3145, AUSTRALIA. Tel: +61 399031423. Email: robert.brooks@monash.edu

2

I

For many, if indeed not most, the study of game theory begins with the

prisoner’s dilemma. Its story and lessons are familiar to all who have taken at

least some undergraduate economics. The game’s influence, however, extends

far beyond that. Its insights are widely drawn upon by researchers not only in

economics, but in mathematics, decision theory, philosophy and right across

the social, behavioral and biological sciences (Dixit & Nalebuff 2008; Kuhn,

2009; Sally, 1995).

The striking prediction of the one-shot prisoner’s dilemma – that defection is

the dominant strategy – follows logically from the assumptions of the game.

But what evidence is there in the real world for the predictions of the

prisoner’s dilemma? Most commonly, proof of its validity is found in the fact

that certain events appear to parallel the conditions of the prisoner’s dilemma.

Whether it be the rivalry of the superpowers, the difficulty of obtaining

international agreements on greenhouse gases, drug taking in elite sports, or

even the actions of the fictional characters in Jane Austen novels, the agents in

each of these scenarios appear to conform with the expectations of the

dilemma (Dixit et al., 2009; Dixit & Nalebuff 2008; Chwe 2013). These

exercises demonstrate that the outcomes of the dilemma can be mapped onto a

number of situations, many of which are themselves purely hypothetical.

These are arguments by analogy, not explicit tests of the dilemma’s empirical

reality.

Aspects of that reality, however, have been captured in other ways. Controlled

experiments conducted within the laboratory or in the field and analysis of the

outcomes of game shows, whose rules incorporate the prisoner’s dilemma,

have provided rich and valuable sources of data and insight. Among other

things, they show that, contrary to expectation, between 30 to 50 per cent of

participants from all backgrounds opt to cooperate; that women and people

over 40 are more inclined to be cooperative than males or young people; and

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that the magnitude of the stake does not appear to have much bearing on the

degree of cooperation (van den Assem et al., 2012; Dixit & Nalebuff 2008;

List, 2004, 2006; Sally, 1995; Roth, 1995; Khadjavi & Lange, 2013).

Yet how translatable are such findings to the world beyond the laboratory and

game show? It is not unfair to say that laboratory experiments and game

shows hardly take place in typical or naturally occurring contexts. In their own

way, each is somewhat contrived; one for reasons of scientific control, the

other for the sake of entertainment. And participants entering either setting are

fully aware of their fabricated natures. They know they are being observed and

recorded and may alter their behavior accordingly. They know this is a game

that they can ‘play to win’ because the consequences of loss are not real (List,

2006). For the most part, any loss incurred has no bearing on life outside the

studio or the laboratory. Expressed differently, the stakes involved are

inevitably low. In experiments, they may be as small as a handful of dollars,

either paid in cash or in kind (Carpenter et al., 2005). Khadjavi and Lange’s

(2013) recent simultaneous prisoner’s dilemma game with female inmates

from a penitentiary in Lower Saxony, for example, expressed its stakes, for

reasons of prison rules, in terms of small quantities of instant coffee, tobacco

and phone credit. Still, the monetary value of the maximum amount winnable

in the actual game, in whichever form it was taken, was just under €2.

In game shows there is, to be sure, the potential of more significant gains. In

one show, Friends and Foe, the stake went as high as $22,000, though the

mean stake was around $3,500 (List, 2004, 2006; Oberholzer-Gee et al., 2003,

2010). In another, the UK program, Golden Balls, players competed for

jackpots with a mean value of £13,416 and median of £4,300, whereas in the

Dutch TV game show Will (s)he share or not?, the median stake was €1,683

(van der Assem et al., 2012; Belot et al., 2010). No doubt, these prizes

represent notable increases on the gains on offer in the experimental

laboratory, including those in low-income countries (Slonim & Roth, 1998;

4

Cameron, 1999; Kocher et al., 2008), yet in terms of real-world dilemmas,

even these higher game show stakes must be considered relatively low. After

all, lives are not hanging in the balance; futures and fates are not being

determined by a single decision. Moreover, in both the laboratory and game

show, stakes are invariably expressed in terms of what can be won: the money

you did not have before, but which you can take home with you. There is no

loss to the participant other than the opportunity cost of making the wrong

choice. Given the widespread prevalence of loss aversion (Kahneman &

Tversky, 1979), such stakes couched purely in pecuniary gains are unlikely to

elicit as much concern as those that involve the participant potentially giving

up something they already have.

Therefore, the findings of neither the laboratory nor game show lend

themselves easily to generalization (Levitt & List, 2008). The problem is that

there are few alternatives to which researchers can turn. As List (2006, p. 470)

has noted, to the best of his knowledge, ‘there does not exist an empirical

examination of behavior in a high-stakes game that mirrors the classic

prisoner’s dilemma tale’.

This paper fills that gap. It offers a rare, real-world natural experiment of a

high-stakes, one-shot, classic prisoner’s dilemma game. The experiment,

which took place in Nazi Germany between 1933 and 1945, was ‘real’ in three

respects. First, it arose out of a context that, while perverse, inhumane and

thoroughly repellent, was not in any way contrived or perceived as artificial to

those involved. Indeed, unlike previous studies which have used prisoners as

their subjects (Khadjavi & Lange, 2013; Churma et al., 2010; Birkeland et al.,

2011), the prisoners in this natural experiment were not – and knew they were

not – simply playing a game concocted by a researcher. Second, it was real

because it was a true prisoner’s dilemma, that is, the ‘game’ that was played

out occurred in precisely the same setting as that which has given the dilemma

its name. Thus, the natural experiment uniquely allows us to observe how

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actual prisoners placed in the classic prisoner’s dilemma setting actually

behaved. Finally, the reality of the experiment is underscored by the truly high

stakes the prisoners were playing for: nothing less than their lives and liberty.

Several interesting findings emerge from studying this natural experiment. As

in previous literature, we find that even in such extreme settings significant

cooperation rates remain. The lower rate of cooperation vis-à-vis games

undertaken in the laboratory or on game shows, however, suggests that the

size of the stake does influence the rate of cooperation. We also find evidence

that age, education, beliefs, political and social affiliations, sense of

community and identity also play roles.

The remainder of this study proceeds as follows. Section 2 discusses the

background and setting of the natural experiment. Section 3 describes the data

used in the paper and how it was collected. Section 4 discusses factors that in

theory encourage cooperation within a prisoner’s dilemma and assesses their

relevance to this context. Section 5 summarizes the results of our estimations

of the prisoner’s choice to defect or cooperate. Section 6 concludes.

II. The Natural Experiment

The natural experiment that this paper examines was discovered by the authors

while undertaking research on juvenile resistance to the Nazi regime between

1933 and 1945. This project studied juveniles and the adults with whom they

collaborated, whose resistance was considered serious enough by the Nazi

authorities for them to be indicted and tried for high treason, an offense, which

on conviction, typically resulted in execution or lengthy spells of

imprisonment (Geerling et al., 2013).

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All individuals in our sample were thus charged with the same, serious offense:

high treason. Prior to their appearance before the People’s Court

(Volksgerichtshof), each resister was investigated, arrested and interrogated.

During interrogation, resisters were separated from their collaborators and

encouraged to confess and assist the authorities in their investigations.

Information obtained through these interrogations benefited the defendants

who provided it and was also used by the authorities against their co-

defendants. Take, for instance, the typical case of two resisters from Hamburg,

who after spending fourteen months in custody, were both convicted in

October 1938 of the high treasonous offences of belonging to a banned

organization and distributing illegal writings. Of these two resisters, one

defected and provided information to the authorities; the other did not. In

sentencing, the defector received a 5 year penitentiary term with all 14 months

of his time in custody deducted because, as the judge explained in summing up,

he had ‘confessed and helped clear up all the facts of the case’. By contrast,

his co-defendant, who had chosen not to defect, was given an 8 year

penitentiary term with only 6 of the 14 months spent in custody being counted

against it. His harsher sentence was attributed by the judge to the fact that he

had, despite ‘the mountain of evidence, foolishly denied every activity’,

behavior which only served ‘to undermine his credibility’. The testimony of

his co-accused, who had defected, however, was accepted by the Court, ‘as

corresponding to the truth’.1

The temptation for resisters to defect was thus strong. By doing so, one could

potentially save one’s life, reduce one’s sentence, or enable oneself to avoid

torture and hard labor. It was realistic for those detained to believe that such

payoffs existed because Nazi sentencing did both exhibit discretion and

reward defection. Tables 1 and 2 show those payoffs in terms of both the

1 Bundesarchiv, Case Files of the Volksgerichtshof, Case Number 1H 26/38,

14 October 1938, Verdict, pp. 9 and 15.

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likelihood of receiving the death penalty and average standardized months in

prison.

Table 1. Payoffs in terms of probability of being executed

Defendant

Defected Cooperated

Co-defendant Defected 0.44; 0.44 0.10; 0.50

Cooperated 0.52; 0.10 0.17; 0.17

Table 2. Payoffs in terms of standardized months in prison

Defendant

Defected Cooperated

Co-defendant Defected 197; 197 98; 229

Cooperated 229; 98 118; 118 Note: Standardized months were calculated in the following way.

1 month in prison = 1 month in prison

1 month in penitentiary = 1.5 months in prison

Execution = 30 years in prison = 360 months in prison

Except when everyone defected, these tables show that those who chose to

defect tended to receive either less harsh forms of punishment (prison rather

than execution, for example), shorter terms in prison or both. The lightest

collective penalty overall, however, occurred when no-one defected. Yet, as

with the classic prisoner’s dilemma, defection was the dominant strategy for

resisters in this situation. They faced no external consequences for pursuing

such a strategy either. Any fear defectors might have felt of punishment by

other opponents of the regime was greatly minimized by the fact that because

of the secrecy involved, not to mention the disinformation publicly spread by

the authorities, no one could know for certain who had defected and who had

not.2 Indeed, we ourselves have only been able to determine whether defection

2 Hearings of the People’s Court were not open to the public. Access was

restricted to carefully picked civil servants, military officers and party officials.

Nor were documents, testimonies, or judges’ summaries publicly available.

8

occurred by reviewing internal court documents not publically available at the

time. The probability of external retaliation for defection was thus extremely

low. Nor was there a long-term to think of. Their actions had no implications

for future cases. No resister reappeared before any Nazi court.

The resisters thus found themselves in a genuine one-shot, high-stakes, multi-

player prisoner’s dilemma. It was a game where it was reasonable for each

resister to believe that one would always get a benefit from defection

irrespective of what others did, but that the benefits would be greatest when

no-one else in the case defected. Conversely, cooperation brought no benefits

unless everyone else in the case cooperated. A single defection completely

undermined cooperation: there was no positive externality from cooperation

unless everyone cooperated.3 In such a scenario, defection was the dominant

Indeed, the cases themselves were not reported in the media, except on rare

occasions when the government saw propaganda value in reporting a verdict.

Even in these instances, no details of the reasoning underpinning the verdict

were provided. Moreover, from the time of arrest and after sentencing, the

ability of political prisoners to communicate with each other and with the

outside world was severally and consciously constrained by the authorities. If

allowed contact at all, their letters were heavily censored and visits from

family members very closely monitored and controlled for content. Beyond

expressing remorse for their actions, prisoners were forbidden to talk about

their case or politics. 3 Even then, there were limits to the benefits. As Tables 1 and 2 show, while a

cooperative equilibrium led to lighter sentencing for all, it did not mean

release. It is important to remember that all defendants had been accused of

attempting to oppose and overthrow the Nazi regime. Indeed, most had been

monitored by the Gestapo for months before arrest and all did have at least

some sort of affiliation or connection with resistance activities. These

circumstances have two implications for how we analyze the situation. First,

they mean we can be confident that no defendants in this natural experiment

chose to cooperate simply because they were ‘innocent’ and thus had nothing

to confess. Second, mutual cooperation between co-defendants, when it

occurred, typically lessened the information at the Nazi’s disposal, rather than

completely deprived them of it. This meant that mutual cooperation tended to

result in a reduction in the harshness of sentences handed down rather than

outright acquittal or the dropping of charges.

9

strategy. Any duress experienced by resisters in reaching their decisions

merely amplified an already strong rationale for defection.4

III. Data

This paper examines the choice to defect or not of a sample of resisters

charged with high treason in Nazi Germany between 1933 and 1945. All 29

cases from this era involving juvenile resistance, and for which there were

multiple resisters, are included. A juvenile is defined here, as it had been in

German law since the Weimar Republic, as someone who was under 18 years

of age at the time of the alleged ‘crime’ (Geerling et al., 2013). In total, there

are 181 resisters in the database, of which 131 were males and 50 females. Of

the males, 45 were juveniles. Ten of the 50 female resisters were juveniles.

30.4 per cent (55 people) of the resisters were juveniles and 69.6 per cent

adults (126 people).

The database contains a wide variety of case sizes and resisters. There are

cases with as few as two defendants and some with as many as 13. The

majority of cases, though, had five or fewer defendants (median = 5). The ages

of resisters at the time of indictment ranged from as young as fifteen right up

to sixty-two, with a median age of twenty-five.

4 We do not subscribe to the view that torture is an external force which

induces irrationality and, hence, distorts the ‘game’s’ outcome. Rather, we see

torture and duress as natural parts of the process of interrogation, in which the

prisoners found themselves. When taken into custody, prisoners expected

physical and psychological duress to be used. As such, enduring or limiting

the extent of torture represented parts of the implicit payoffs faced by

prisoners in this real-world dilemma. The economic role of torture was thus to

shift payoffs – or, in other words, the stakes involved – to a position that made

defection even more strongly the dominant strategy. We do not believe that

individuals cease to be rational when duress is introduced.

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Table 3: Number of defendants per case and age at indictment of resisters

Cases with: Number

of cases

Age at

Indictment

Number of

defendants

Age at

Indictment

Number of

defendants

2 defendants 2 15 1 39 2

3 defendants 5 16 7 40 5

4 defendants 7 17 13 41 2

5 defendants 3 18 23 42 3

6 defendants 1 19 8 43 2

7 defendants 2 20 13 44 1

8 defendants 1 21 7 45 2

9 defendants 1 22 4 46 6

10 defendants 2 23 8 47 3

11 defendants 0 24 6 48 1

12 defendants 3 25 8 49 4

13 defendants 2 26 1 50 3

27 3 51 1

28 2 52 1

29 2 53 2

30 0 54 1

31 2 55 2

32 4 56 2

33 5 57 1

34 4 58 2

35 2 59 0

36 4 60 3

37 3 61 0

38 1 62 1

The data used in this paper were extracted from the official state records of

juvenile cases tried before the People’s Court collated by the Resistance as

High Treason (Widerstand als Hochverrat) project, which combined material

on resistance groups stored in the archives of the Federal Republic of

Germany and Austria with previously inaccessible files from the former

German Democratic Republic, Prague and Moscow (Zarusky & Mehringer,

1998). The microfiche series it generated contains among other things the

court files that document the judicial prosecution of juveniles (and those who

11

abetted them) charged with high treason. These files include a wealth of

information on the indictment, investigation and trial of each defendant.

Through searching these records, we have been able to reconstruct the profiles,

family backgrounds, and influences of all resisters who were juveniles, or

collaborated with juvenile resisters, charged with high treason between 1933

and 1945. Wherever possible, we have crosschecked and supplemented our

information with the entries for individual resisters found in the leading

encyclopedias of German resistance (Steinbach & Tuchel, 1998, 2000). This

database not only affords a new perspective on those German and Austrian

youths who resisted the Nazi state, but, with careful reading of each individual

case file, also enables us to determine which resister had defected during

interrogation.

This was possible because Gestapo internal reports (i.e. they were not intended

for public disclosure) of investigations, retained in the unpublished case files,

indictments and verdicts of the People’s Court, would freely refer to a

resister’s ‘full and frank’ confession or how the evidence provided by them

was used to convict other resisters.5 For example, according to one such report,

it was noted that during his interrogation, one 18-year old juvenile from

Vienna charged with writing anti-Nazi pamphlets had made a full confession.

He had also admitted to ripping to pieces an oil painting of Hitler, though now:

‘he feels shame for his actions and recognizes his error.’ Furthermore, he

wished to atone by writing a new work ‘in which he will show his change of

heart toward National Socialism’.6 Similarly, in another report about the

interrogation of a resister from Leipzig, it was stated that the prisoner after

5 We have read hundreds of internal documents and found no evidence of

interrogators fabricating reports or confessions. Indeed, whenever a prisoner

subsequently denied or retracted elements of an earlier statement, this was

clearly recorded in later reports. Such a practice suggests that fabrication, if it

occurred at all, was not common. 6 Zarusky & Mehringer (1998), Microfiche 0428, Case Number 7J 104/44,

Indictment p. 3, Verdict p. 4.

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much resistance only ‘brought himself to a confession after being told that

everyone had already spoken’.7 Failures to defect were also recorded by

Gestapo interrogators and were typically attributed to the resisters’ alleged

obstinacy, remorselessness, immorality or just complete lack of honor. Thus,

in the Gestapo files of one Austrian woman, it was reported that despite

‘persistent reminders to be honest’ stretching over four months, she refused to

cooperate with investigators. She was, nevertheless, convicted of high treason

and sentenced to five years in prison.8

This Austrian resister was far from unique in not defecting. In 41.4 per cent of

the cases at least one defendant did not defect. In two cases (6.9 per cent) all

of the defendants opted to cooperate. The majority of cases (58.6 per cent)

resulted in the expected non-cooperative equilibrium. As for individuals, 31,

or 17.1 per cent, chose cooperation. Of those 31 resisters who cooperated, 80.6

per cent had at least one co-defendants defect on them. Only 6 resisters had all

of their co-defendants cooperate as well. By contrast, 55.2 per cent of resisters

were involved in cases where all defendants defected.

The motivations to defect were strong, but not always overwhelming. With

stakes that were life-threatening, overall rates of cooperation fell markedly

from the 30 to 50 per cent typically exhibited in experimental or game show

conditions, including those conducted on prisoners (Khadjavi & Lange, 2013;

Churma et al., 2010; Birkeland, 2011), to 17.1 per cent. Thus, stakes do seem

to matter. Interestingly, though, they are not all that matter. Even the threat of

torture and execution does not appear to have been able to snub out all desire

to cooperate.

7 Bundesarchiv, Case Files of the Volksgerichtshof, VGH/Z H 286, Leipzig

Gestapo Report, 12 July 1938, Sonderband Lippert, p. 16. 8 Bundesarchiv, Case Files of the Volksgerichtshof, VGH/Z K, Gestapo Report,

14 July 1942, p. 34. Dokumentation Österreichischen Widerstandes, Case Files

of the Volksgerichtshof, DÖW 20000/K653.

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Table 4. Cooperation rates by cases

Cases where: Number (percentage) of cases

All defendants cooperated 2 (6.9)

Some but not all defendants

cooperated

10 (34.5)

No defendants cooperated 17 (58.6)

Table 5. Cooperation and defection rates by defendants and co-

defendants actions, numbers and percentages (in brackets).

Defendant

Defected Cooperated Total

Co-defendants Defected 100 (55.2) 25 (13.8) 125

Cooperated 50 (27.7) 6 (3.3) 56

Total 150 (82.9) 31 (17.1) 181

Decomposing cooperation further reveals striking differences between genders

and age groups. Table 6 divides all resisters into four distinct age groups:

juveniles (15 to 17 year olds), young adults (18 to 27 year olds), mature adults

(28 to 40 year olds), and older adults (more than 40 years old). Each age group

is further divided by gender.

Table 6 shows that female resisters were noticeably more likely to defect than

their male counterparts (92 per cent compared to 79.4 per cent). This disparity

between the genders appears to hold across all ages groups, except for mature

adults where the number of female resisters are probably too small to draw

strong conclusions. This finding, discussed in Sections 5 and 6, stands in stark

contrast to the existing literature which often observes the reverse (Oberholzer

et al., 2003; List, 2006).

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Table 6. Cooperation and defection rates by age and gender

All Ages

Combined

Gender Number

(percentage) who

defected

Number

(percentage) who

cooperated

Total

Male 104 (79.4) 27 (20.6) 131

Female 46 (92.0) 4 (8.0) 50

Total 150 (82.9) 31 (17.1) 181

Juveniles

(up to 18

years)

Number

(percentage) who

defected

Number

(percentage) who

cooperated

Total

Male 34 (75.6) 11 (24.4) 45

Female 9 (90.0) 1 (10.0) 10

Total 43 (78.2) 12 (21.8) 55

Young

Adults

(18-27

years)

Number

(percentage) who

defected

Number

(percentage) who

cooperated

Total

Male 28 (90.3) 3 (9.7) 31

Female 16 (100.0) 0 (0.0) 16

Total 44 (93.6) 3 (6.4) 47

Mature

Adults

(28-40 years)

Number

(percentage) who

defected

Number

(percentage) who

cooperated

Total

Male 24 (92.3) 2 (7.7) 26

Female 9 (90.0) 1 (10.0) 10

Total 33 (91.7) 3 (8.3) 36

Older Adults

( 40+ year)

15

Number

(percentage) who

defected

Number

(percentage) who

cooperated

Total

Male 18 (62.1) 11 (37.9) 29

Female 12 (85.7) 2 (14.3) 14

Total 30 (69.8) 13 (30.2) 43

Turning to age, it is noteworthy that cooperation rates varied by stage of life.

Juveniles cooperated more than on average (21.8 per cent). The high rate of

cooperation among teenagers, however, fell away sharply upon attaining

maturity. Only 6.4 per cent of young adults and 8.3 per cent of mature adults

cooperated. After 40 (older adults), however, cooperation rates rapidly

increased to 30.2 per cent. This disparity between younger and older adults is

consistent with the findings of Oberholzer-Gee et al. (2003) who discovered

that adults less than 28 years old on the game show Friend or Foe were far

less ready to cooperate than those older than them (38.7 per cent to 51.6 per

cent).

While List (2004) has previously studied the behavior of 19 year olds in one-

shot and multiple-shot public good games, ours is the first study to measure

cooperation rates among teenagers as young as fifteen in a classic prisoner’s

dilemma game. The rates found are high both relative to those exhibited by

adults under 40 years of age and when one takes into consideration the

extreme context in which the ‘game’ took place. They suggest that differences

in cooperation rates are not simply a reflection of being old or young, but

rather products of the varying social position, roles and attitudes of the

different age groups.

IV. Cooperation

Since the earliest testing of the prisoner’s dilemma in laboratories, the high

rates of cooperation among subjects observed has attracted considerable

16

attention (Roth, 1995). Broadly speaking, three types of explanation for

cooperation, or solutions to the standard prisoner’s dilemma, have been put

forward. The first of these genres relates to features which are either added to,

or alter, the original game, making its subjects more amenable to cooperative

behavior. Among these changes, the most common highlight the infinite

repetition of the game, the imposition of credible and sufficiently large

penalties outside the game to those who defect within it, and the reduction of

the risk of cooperation achieved by ensuring that there is always some

individual benefit to those who cooperate (Dixit et al., 2009; Kümmerli et al.,

2007). The introduction of asymmetry into the game in terms of either the

information players have about their opponents’ nature and payoffs, or the

actual payoffs of the different players, or in the player’s ability to think

strategically can also engender cooperation (Dixit et al., 2009; Kahn &

Murnighan, 2008; Chwe, 2013). None of these circumstances apply to our

scenario. Resisters to the Nazi regime found themselves in a one-shot game,

where no credible external penalty was possible because detection of defection

itself was not possible, where cooperation brought no benefit unless everyone

else cooperated, and where payoffs, knowledge and abilities were not

systematically different.

A second strand of explanation concerns itself with the attitude taken by some

players in certain specific, usually artificial, ‘game’ settings. Knowing, for

example, that they are being observed, players in both experiments and game

shows can ‘play up’ for the audience. They do not behave as they would

normally because they figure that how they perform in the game may have

ramifications outside the game. Some may behave in the way they believe is

expected of them, whereas other may become particularly concerned about

being publically seen as nasty or anti-social and curb their self-interest

accordingly (List, 2006; van den Assem et al., 2012). Context also seemingly

matters here. Stakes that might be regarded as high in everyday life and would

normally be worth defecting for become ‘peanuts’ in other contexts where the

17

prizes that are being played for are even larger (van der Assem et al., 2012).

Neither of these features displayed by some game show participants would

have had much impact on the choice of resisters under interrogation in Nazi

Germany. While many may have wished to have pleased their captors by

defecting, they only did so within the ‘rules of the game’, that is, in return for

a hoped for lighter punishment. They did not alter their behavior in order to

satisfy an external, non-participating audience. No doubt, examples of the ‘big

peanuts’ phenomenon may have taken place in the interrogation room,

although we have not found any in the records. But it is hypothetically

possible. Resisters who, say, in 1938, before being detained, may have

normally betrayed their collaborators in return for a payment of 20,000 RM

(Reichmarks) being secretly made to their relatives, after arrest may well have

spurned such a hypothetical offer while the threat of execution or life

imprisonment remained hanging over their heads. Even if it existed, however,

such phenomena would have had no bearing on a resister’s choice to defect or

not.

The third variety of explanation for cooperation focuses on beliefs held or

thought patterns exhibited by players which enable them to overcome self-

interest. Some are allegedly driven to cooperate by an ethical or moral

imperative. It could be religious in origin, as in the biblical injunction to ‘do

unto others as you would have them do to you’ (Luke 6: 31), or have more

philosophical roots, such as the Kantian Categorical Imperative to ‘take only

such actions as you would like to see become a universal law’ (Dixit &

Nalebuff, 2008). Whatever its origins, it may encourage players to adopt a

form of irrational ‘quasi-magical thinking’ that leads them not only to ignore

their own self-interest, but behave as if their own actions (not to defect in this

case) can somehow influence the independent actions of others to act similarly

(Shafir & Tversky, 1992). As a result, some players can continue to cooperate

even in situations when all the evidence suggests there is little point in so

doing.

18

A related, yet clearly distinct, theme in the literature centers on a player’s

genuine belief that the others in the game will cooperate. When such belief

exists, that player is willing to choose cooperation even though in so doing

they expose themselves to considerable risk of loss. Unlike moral imperatives

or ‘quasi-magical thinking’, such ‘conditional cooperation’ is based on neither

wishfulness nor metaphysical values (Fischbacher et al, 2001; Frey & Meier,

2004; Oberholzer-Gee et al., 2010). Rather, it is grounded in empirical

evidence that the belief is justified. Players look to past experience, character

traits and the words and actions of other players for clues to their

trustworthiness. Good communication with another player, the ability to be

able to look them in the eye and hear their voluntary promises of cooperation

are all factors conducive to the building of trust (Belot, 2010; Sally, 1995).

While it is impossible to determine the extent to which a resister’s choice to

cooperate was influenced by particular thought patterns or moral principles, it

is highly probable that their actions in many cases were conditioned by a

belief that their co-defendants would also cooperate. Such confidence was

shaped by the fact that often the defendants knew each other and shared

common backgrounds, experiences and aspirations. They also believed the

same things and were members of the same communities, organizations and

groups, affiliations that formed key elements of their individual identities.

Identity is an important influence on behavior (Akerlof and Kranton, 2010).

For many resisters, their workplace and membership of political parties,

religious and ethnic organizations, voluntary associations and occupational

classes defined much about who they were and how they behaved. To

challenge one’s very identity by yielding to a Nazi system fundamentally

opposed to everything you stood for and held dear was no doubt a powerful

deterrent for some. Moreover, by defecting, one also betrayed others from

their community, party, or organization and further augmented the

psychological torment, loss of identity and sense of belonging. Although the

degrees to which resisters felt the bind of identity varied, for some, as

19

evidenced by their testimonies, it was deeply held and was assumed to be

similarly held by co-defendants.

V. Results

To explore the determinants of cooperation among resisters charged with high

treason in Nazi Germany, we estimate a probit model around a latent

regression of the form

Cooperation = iX +i

where Cooperation is the resister’s choice to cooperate or not, X is a vector of

personal environmental characteristics related to that resister, i is the

estimated response coefficient vector, and i is the random error term.

In the estimations reported below, two varieties of the dependent variable,

Cooperation, are investigated: (i) the resister’s choice between cooperation

and defection (Cooperation versus Defection), and (ii) the resister’s choice to

defect or not when a co-defendant has defected (Co-defendant Defection

versus Both Defection). The first is just the straightforward choice to defect or

not, while the latter investigates whether defection by co-defendants elicits

different behavior from a resister. In other words, did the actual defection of a

co-defendant make a resister more likely to defect as well? While such a

defection by a co-defendant would not actually be known by the resister, it is

conceivable that a resister may have formed opinions as to the likelihood of a

co-defendant defecting. To the extent that these opinions were based on valid

assessments of the co-defendants themselves, one would expect that they

would closely match the actual pattern of defection observed in the data. If this

were the case, then differences in the determinants of the resister’s choice

between the two versions of Cooperation may be detectable.

20

The vector X captures variables that may influence the choice to cooperate or

not. Variables included in X are listed in Table 7 and encapsulate a variety of

factors related to the resister’s personal history, education, occupation,

employment, beliefs and memberships. Most variables are dichotomous and

equal 1 if the characteristic is present and 0 otherwise. For example, ‘Engaged

or married’ equals 1 if the resister is either married or engaged; 0 if they are

not. A few variables are categorical and are scored in ascending order. Thus,

the resister’s highest educational achievement variable, ‘Education’, is

constructed such that if that achievement was primary school it would equal 1,

vocational or trade school 2, high school 3, and university 4. In addition to the

variables given in Table 7, X also includes the age of the resister at the time of

indictment, the number of co-defendants involved in their case, and dummies

for the early phases of the war (September 1939 to May 1941) and the period

after the invasion of the Soviet Union (June 1941) and the beginning of war on

two fronts.

Table 7. Personal and environmental characteristics of resisters

Number Percentage

Personal History

Male 131 72.4

Female 50 27.6

German1 158 87.3

‘Mixed blood’: not regarded as of full German

ethnicity by the Nazis2

16 8.8

Foreigner &/or stateless 7 3.9

Spent time Outside the Reich3 21 11.6

Engaged or married 72 39.8

Experienced chronic health problems 11 6.1

Family member(s) persecuted by the Nazis 7 3.9

Juvenile or young adult with at least one parent

deceased

13 7.1

Parents divorced 6 3.3

Close family member(s) killed in war 12 6.6

Immediate family member(s) engaged in anti-regime 65 35.9

21

activities

No adult involvement in their act of resistance 21 11.6

Previous charges 37 20.4

Served in WWI 22 12.2

Served in WWII 14 7.7

Highest Educational Achievement

University 7 3.9

High school 47 26.0

Vocational or trade school 67 37.0

Primary 60 33.1

Occupation

Student 6 3.3

No particular occupation 13 7.2

Blue collar 120 66.3

White collar 26 14.4

Professional 11 6.1

Business or property owner 5 2.8

Employment

Employed 130 71.8

Unemployed 8 4.4

Not in the labor force 43 23.8

Beliefs and Memberships

Supporter of Austrian independence 123 68.0

Denied entry or never joined Hitler Youth or BDM4 15 8.3

Expelled from Hitler Youth or BDM (prior to charges

being laid)

6 3.3

Left Hitler Youth of BDM of own accord 12 6.6

Member of youth street gang 10 5.5

Member of a Communist organization 60 33.2

Member of a Social Democratic organization 27 14.9

Member of the Nazi party 8 4.4

Voluntary member of a non-political and non-

religious organization

23 12.7

Strong religious affiliation 43 23.8

Skilled laborer5 93 51.4

Engaged in anti-war activities 138 76.2 1. ‘German’ includes Austrians. Austria became part of Greater Germany after the Anschluss of March 1938.

2. The term, ‘mixed blood’ or Mischlinge in German, typically referred to individuals with at least one parent or

grandparent of Jewish descent.

3. This figure excludes resisters who had spent time outside Germany only as part of their military service.

4. Bund Deutscher Mädel (League of German Girls).

5. A ‘skilled laborer’ is someone who had completed or was doing an apprenticeship or some formal vocational

training.

22

The first two columns of Table 8 relate to the determinants of the simple

choice between cooperation and defection. They show the statistical

significance of eight variables, the marginal effects of which are given in

square brackets.9 One of these significant variables is age. Once allowance is

made for other influences, which are discussed shortly, age remains highly

significant. For each year of age, the probability of defection declined by 1.6

per cent, a finding which among other things suggests that the lower rates of

cooperation observed among young and mature adults are probably better

explained by broader characteristics of these age groups’ experiences rather

than their age per se.10

Table 8. Binary Probit Models of Cooperation and Defection

Cooperation

vs. Defection

Cooperation

vs. Defection

Co-

defendant

Defection

vs. Both

Defection

Co-

defendant

Defection

vs. Both

Defection

Age -0.056

(0.00)***

[-0.016]

-0.053

(0.00)***

[-0.016]

-0.068

(0.00)***

[-0.019]

-0.064

(0.00)***

[-0.018]

Education -0.366

(0.05)**

[-0.104]

-0.414

(0.01)***

[-0.117]

-0.417

(0.04)**

[-0.116]

-0.414

(0.02)**

[-0.115]

Member of

Social

Democratic

organization

1.544

(0.02)**

[0.438]

1.465

(0.02)**

[0.415]

1.620

(0.02)**

[0.450]

1.530

(0.03)**

[0.425]

Anti-war

activist

-0.888

(0.05)**

[-0.252]

-0.782

(0.07)*

[-0.222]

-1.289

(0.03)**

[-0.357]

-1.239

(0.03)**

[-0.344]

Skilled Laborer -0.830 -0.902 -0.755 -0.823

9 Variables not reported in Table 8 or discussed in the text were found to be

insignificant in all specifications or capable of being estimated. For the

insignificant variables, their inclusion in the models does not impact the

significance of the other variables in Table 8 indicating robustness in the

results. 10

Modeling age non-linearly proved insignificant.

23

(0.01)***

[-0.235]

(0.01)***

[-0.256]

(0.05)**

[-0.209]

(0.02)**

[-0.228]

Member of

Non-political or

religious

organization

-0.988

(0.01)***

[-0.280]

-0.912

(0.02)**

[-0.258]

-1.356

(0.00)***

[-0.376]

-1.314

(0.00)***

[-0.365]

No Adult co-

defendant

-1.292

(0.01)***

[-0.366]

-1.608

(0.00)***

[-0.456]

-1.188

(0.06)*

[-0.330]

-1.324

(0.01)***

[-0.368]

Juvenile or

young adult

with at least one

parent deceased

-0.995

(0.05)**

[-0.282]

-1.038

(0.04)**

[-0.294]

-1.158

(0.05)**

[-0.321]

-1.177

(0.04)**

[-0.327]

Occupation 0.050

(0.75)

[-0.235]

0.134

(0.43)

[0.037]

Male -0.304

(0.47)

[-0.086]

-0.269

(0.55)

[-0.075]

Number of co-

defendants

0.043

(0.41)

[0.012]

0.005

(0.94)

[0.001]

Member of

Communist

organization

-0.064

(0.86)

[-0.018]

-0.036

(0.93)

[-0.010]

Strong religious

affiliation

-0.199

(0.59)

[-0.056]

-0.067

(0.88)

[-0.019]

McFadden R2 0.355 0.348 0.380 0.374

LR test 58.905

(0.00)***

57.603

(0.00)***

52.958

(0.00)***

52.124

(0.00)***

Prediction

Defection

143/150

(p>0.5)

137/150

(p>0.6)

145/150

(p>0.5)

139/150

(p>0.6)

146/149

(p>0.5)

144/149

(p>0.6)

144/149

(p>0.5)

144/149

(p>0.6)

Prediction

Cooperation

16/31

(p<0.5)

19/31

(p<0.6)

15/31

(p<0.5)

19/31

(p<0.6)

13/24

(p<0.5)

14/24

(p<0.6)

12/24

(p<0.5)

14/24

(p<0.6) Notes: p-values are in parenthesis. Marginal effects are given in square brackets. * denotes significance

at the 10 per cent level, ** at the 5 per cent, *** at the 1 per cent.

24

Nor does gender appear to have been a key determinant of cooperation. The

explanation for the relatively low cooperation rates of female resisters thus

appears to lie, not in their gender, but ability to acquire other characteristics

that did deter defection. It is also noteworthy that while the coefficient on the

number of co-defendants in a case has the right sign (positive), it is

statistically insignificant. On the whole, therefore, the choice made by resisters

does not appear to have been influenced by the existence of more or less co-

defendants, even though, ceteris paribus, more co-defendants increased the

likelihood of a defection occurring within a case and, hence, the personal risk

of pursuing a cooperative strategy (since such cooperation could only bring

benefits if all cooperated). Other factors seemingly pressed more heavily in

their deliberations.

Of these, education appears to have been central. Defection was inversely

related to the resister’s highest level of educational attainment. For each ‘step’

in their attainment (from primary through tertiary), the probability of defection

decreased by about 10 per cent. Two factors lie behind this finding. Better

educated resisters were, firstly, less inclined to capitulate to the intellectually

bereft Nazi view of the world and, second, less likely to be duped by Gestapo

interrogation techniques.

Table 8 also provides statistical evidence that being a member of a social

democratic organization increased your chances of becoming a defector by as

much as 41.5 per cent. This result needs to be interpreted within its proper

context. Most resisters charged with high treason were individuals deeply

committed to a cause that was based upon a strong, often dogmatically

interpreted, ideological, theological or philosophical value system

fundamentally in conflict with the Nazis’ (e.g. Communism, Catholicism,

Mormonism, and Pacifism). Many, of course, chose to defect anyway, but,

from what we know about these movements and their belief structures, the

idea that such a course of action represented a betrayal of the cause must

25

surely have weighed heavily in the mind (Benz et al., 1996; Steinbach &

Tuchel, 2000, 2004). The significance of anti-war activism in the estimations –

a characteristic which reduced defection by around 25 per cent – and the

similarly correct, though statistically insignificant, negative signs on the

coefficients for involvement in communist and religious organizations are

consistent with this notion. By contrast, involvement in social democratic

politics carried less ideological or theological baggage and less party or church

discipline. Social democracy was more tolerant of deviation and more flexible

in approach (Steinbach & Tuchel, 2000, 2004). As a result, defection brought

with it potentially less stigma. Members of social democratic organizations,

while still adamantly opposed to Hitler and Nazism, were intellectually and

politically freer to evaluate their situation from a pragmatic perspective.

Political or religious causes were, of course, not the only affiliations that could

impinge on the decision to cooperate. Skilled workers were among the most

heavily unionized, organized and cohesive group in twentieth-century

Germany. Their training placed them apart from and above other sections of

the workforce and encouraged a sense of camaraderie with fellow skilled

workers.11

It was a connection that saw many collaborate in acts of resistance

against a regime which had abolished their unions and sought to constrain

their independence and collective strength within the Nazi-run German Labor

Front (Steinbach & Tuchel, 1990, 2000, 2004; Peukert, 1991). Resisters who

were skilled laborers were, as a consequence, about 25 per cent less likely to

defect.

Similarly, resisters who were members of voluntary non-political, non-

religious organizations, such as the Red Cross, Boy Scouts, hiking societies,

gymnastic clubs, and sporting associations exhibited a similar inclination

11

It is noteworthy that levels of occupation (i.e. blue collar, white collar,

professional, business and property owners) had no significant statistical

impact on cooperation. It was the shared skills of artisans and their

organizations that bound.

26

toward cooperation. Often taken as measures of social capital, participation in

these organizations, which proliferated in interwar Germany (Satyanath et al.,

2013), also fostered trust between members and a sense of community

(Putnam, 2000; Durlauf & Fafchamps, 2004; Field, 2003), attributes which

together appear to have engendered in some a belief that mutual cooperation

was plausible. In fact, involvement in these organizations reduced the

likelihood of defection by about 25 per cent. This is an interesting finding, for

it emphasizes the importance of social capital and community in building trust

and cooperation. Even in these most horrendous of circumstances, these could

make a significant difference. Consider the case of a skilled laborer active in,

say, the Red Cross. Our estimations indicate that such an individual would

have been around 50 per cent more likely to cooperate. Being part of the

community and playing an active role in civil society in some circumstances

galvanizes cooperation.12

Another distinct group within the experiment were resisters aged between 15

and 17. This group had a strong sense of identity that overlapped, yet was

separate from, those of their adult co-resisters. What distinguished juvenile

from adult resistance were the degree of independent, small group decision

making involved; its atomistic nature; its frequent lack of strong adult

supervision; and the absence of any attempt to fit actions into a broader

strategy for change (Geerling et al., 2013). Juveniles also evidently felt securer

with each other than adults. Not only were cooperation rates higher among

juveniles than for any other age group except that of the over 40s, but

cooperation was more forthcoming when all the other defendants in a case

were also juveniles. When that was the case, the likelihood of defection fell by

as much as 45 per cent.

12

Such cooperation, of course, need not always lead to beneficial outcomes.

Satyanath et al. (2013) argue that the development of social capital in Weimar

Germany facilitated the rise of the Nazi party.

27

While the bonds of youth may have created solidarity among juveniles, it

appears not to have come at the expense of other attachments, least of all those

of the family. Table 8 reveals that juveniles and young adults whose parents

were both alive at the time of interrogation were about 28 per cent more likely

to defect. It was commonplace for Gestapo interrogators to threaten the well-

being of family members. Unsurprisingly, teenagers and young adults, most of

whom still lived at home and cared about their parents’ welfare, were

particularly vulnerable targets for such intimidation.

Columns 3 and 4 of Table 8 provide an estimate of a model of choice where

one of the other co-defendants defected. The most striking aspect of this

model is its very close similarity, both in terms of significant variables and

marginal effects, with the plain defection versus cooperation model discussed

above. Whether a co-defendant defected or not seemingly had little bearing on

the process used by resisters to make their choice. This might have been

because resisters did not take beliefs about what other defendants might do

into consideration or, alternatively, because whatever beliefs they might have

formed on the basis of association did not accord with reality. Either way,

these findings suggest that in a one-shot prisoners’ dilemma like this, where

knowledge of which types of players had defected in the past is unknown,

conditional cooperation merely based on previous rounds of the game played

by different players is not likely to be an important consideration. This is not

to say, of course, that resisters could not have formed systematic beliefs about

the probable actions of other resisters with certain characteristics, but, given

the context, such beliefs, if they existed, could not have been formed on the

basis of knowledge about whether specific resisters or others like them had

previously defected when interrogated by the Gestapo. Unfortunately, with

only 29 cases in the database, more than half of which have at least five

defendants, it is not possible to test rigorously whether one resister’s decision

could be influenced by a specific characteristic of another.

28

VI. Concluding Comments

To the best of our knowledge, this study is the first to analyze cooperative

behavior within a real-world, one-shot, high-stakes prisoner’s dilemma that

conforms closely to the story so often related in textbooks. The ‘prisoners’ in

question were individuals arrested and charged with high treason in Nazi

Germany between 1933 and 1945. Investigation of this natural experiment

reveals four major insights.

First, it confirms that the prisoner’s dilemma is a powerful tool for analyzing

real-world situations. The theoretical prediction that defection is the dominant

strategy of this game holds even when, as in this case, many of the subjects

subscribed to strong ideological or spiritual belief structures: the vast majority

of resisters did in fact defect. However, as in experiments and on game shows,

a non-negligible share – some 17.1 per cent – of resisters opted to cooperate,

even when faced with the possibilities of torture and execution.

Second, our findings suggest that the size of what is at stake can impact the

extent of social preferences exhibited. Our natural experiment has the highest

possible stake: one’s life and liberty. While a surprisingly large share of

resisters still chose not to defect, the observed cooperation rate was well below

that reported in previous literature on the prisoner’s dilemma. These results

indicate that, perhaps, the stakes tested in experiments and offered on game

shows have not been high enough or significantly different from each other (or

indeed both) to isolate the effect clearly. Moreover, we suspect that the

artificial contexts, in which most of these experiments typically take place,

impact players’ behavior as well.

Third, the paper finds evidence that age, gender and education influence

cooperation rates, though not in as straightforward a way as usually claimed.

Age and gender are important, but not in isolation. They need to be read in

context and in conjunction with other factors. We find, for example, that

29

female resisters defected at a greater rate than male, not because of their

gender per se, but because their place in German society at the time denied

them the opportunities to acquire the characteristics most conducive to

cooperation. In the 1930s and 40s, few women received more than basic

schooling, few were trained to become skilled laborers, and few were formally

involved in the major political and religious movements of the day (Wickert,

1995, 1996).

Fourth, this natural experiment has revealed the important roles that beliefs,

identity and community can have on overcoming Nash play. While the

importance of each might vary by context – political beliefs, for example, may

have little impact in the laboratory where all that is being played for is a few

dollars – they arguably have greater significance in many real-world situations

where consequences endure and the social implications of wide-scale

defection are problematic. Our findings suggest that investing in social capital

and encouraging deeper engagement with civil society may be two ways in

which communities can mitigate some of the consequences of the prisoner’s

dilemma.

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