The End of ( Traditional ) Emergence : Introducing Reactive Emergence
admits into the University of Texas system the top few percent of students from each high school .
Percentage plans “ encourage parents to keep their children in low performing segregated schools , and discourage students from taking challenging classes that might lower their grade point averages .”
This unintended consequence qualifies as reactive emergence : establishing the percentage plan serves as the change to the environment ; the decisions ( a ) by parents to keep their children in low-performing schools and ( b ) by students to avoid challenging courses are the agent-mediated redirected energy flows . Most unintended consequences qualify as reactive emergence .
• Braess ’ s paradox 17 describes situations in which the addition of a new road to an existing network results in additional rather than reduced congestion . The new road is the change to the environment ; the choice by drivers to use the new road — and thus unintentionally and paradoxically to create additional congestion — is the agent-mediated energy flow .
• The evolution of antimicrobial-resistant “ superbugs ” qualifies as reactive emergence . The widespread use of antibiotics constitutes the change to the environment . The spread of genes capable of resisting those antibiotics qualifies as an intrinsic redirection of energy flows . The redirection is intrinsic because it depends on the survival or nonsurvival of bacteria bearing the resistant genes . It is not directed by the antibiotics .
• The redirection of a river by digging a new channel and blocking the old one is not reactive emergence , even though the new channel and the blocking of the old one are changes to the environment and the river ’ s new path is a redirection of energy flows . It fails to be reactive in that the redirection of the river is neither agent mediated nor intrinsic — the river is not an agent and did not change its own path . However , once a river has been rechanneled , the changes in the surrounding flora and fauna constitute reactive emergence .
• My favorite — and probably apocryphal — story concerns a country infested with snakes . The interior minister offered a bounty for each dead snake . The enterprising citizens established snake farms .
17 See Section 8.1 of Easley and Kleinberg ( 2010 ).
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