The
Prisoner’s
Dilemma
5
5
0
10
10
0
1
1
Or why
cooperation
makes people better off.
Here’s two prisoners, Tom and Jerry:
Tom
Jerry
Tom’s told:
– Here’s the deal…
(Yeah, Jerry’s offered the same deal)
(1)
If you rat each other out,
then each of you will serve 5 years in prison.
(1)
If you rat each other out,
then each of you will serve 5 years in prison.
You rat Jerry out
Jerry rats you out
5
5
(2)
If you rat Jerry out,
and Jerry remains silent,
then you will go home free
and Jerry will serve 10 years in prison.
(2)
If you rat Jerry out,
and Jerry remains silent,
then you will go home free
and Jerry will serve 10 years in prison.
You rat Jerry out
0
10
(3)
If Jerry rats you out,
and you remain silent,
then you will serve 10 years in prison
and Jerry will go home free.
(3)
If Jerry rats you out,
and you remain silent,
then you will serve 10 years in prison
and Jerry will go home free.
Jerry rats you out
10
0
(4)
If you and Jerry both remain silent,
then both of you will serve 1 year in prison.
(4)
If you and Jerry both remain silent,
then both of you will serve 1 year in prison.
1
1
What should Tom choose?
remain silent
rat Jerry out
(And what should Jerry choose?)
rat Tom out
remain silent
From the outsider’s perspective
(1)
(2)
Tom rats Jerry out
Tom rats Jerry out
Jerry rats Tom out
5
5
(3)
0
10
1
1
(4)
Jerry rats Tom out
10
0
(1)
5
+
5
= 10
(3)
10
+
0
= 10
(2)
0
+
10
= 10
(4)
1
+
1
=
2
(1)
5
+
5
= 10
(3)
10
+
0
= 10
(2)
0
+
10
= 10
(4)
1
+
1
=
2
2 < 10
Which means, they would be better off,
if they both cooperated and remained silence.
(Both of them would serve 1 YEAR in prison.)
From Tom’s perspective
(the same is true for Jerry)
If I rat Jerry out:
I rat Jerry out
(1)
(2)
Jerry rats me out
5
0
If I remain silent:
(3)
(4)
Jerry rats me out
10
1
If I rat Jerry out:
5
+
If I remain silent:
0
=
5
10
+
1
= 11
If I rat Jerry out:
5
+
If I remain silent:
0
=
5
10
+
1
= 11
5 < 11
That is, if Tom and Jerry are purely rational persons,
they will surely rat each other out.
(And both of them will serve 5 YEARS in prison.)
But…
1 YEAR in prison is better then 5 YEARS in prison.
That is: the guys should have cooperated.
Conclusion
In the end of the day,
Cooperation
makes everyone better off.
Embrace
Cooperation!
Thank You!