Relative Utility - Behavioral Mathematics for Game AI - page 224

game situations than in others. In a first-person shooter (FPS) game, for example,
we need to consider a different constellation of factors than we would be concerned
with in a real-time strategy (RTS). Similarly, there will be different considerations
in an RPG than there would be in a sports game. For purposes of illustration, how-
ever, we can conjure up an example that is similar to our moral dilemmas above.

I NTHE G AME Hippocratic Morals

Imagine that we are a medic for a platoon of soldiers. We have a number of seri-
ously wounded squad-mates. Three of the injured are normal combatants. One of
them, however, is the only demolitions expert in the group. Given the arrangement
of the situation and the relative severity of the wounds, we must choose between
saving the lives of the three normal soldiers or the life of the demolitions expert.
We are also aware that the demolitions expert has the ability to destroy the enemy
forces that are massing for a final assault that will assuredly wipe out the entire
platoon. As the medic, who should we tend to?
At first, the exercise seems strictly mathematical: Three people are more impor-
tant than one. However, we are also aware that there is another layer involved. We
must consider that by saving the demolitions expert, we are actually doing a greater
good (by preventing an inevitable greater loss). The unfortunate loss of the other
three soldiers is a by-product. We are not choosing to kill them; we are choosing to
save many people over and above the four injured soldiers that are in our immedi-
ate care. By realizing that extra layer of abstraction in the problem, we avoid the
apparent contradiction that saving one person is more important than saving three
people.
To arrive at the solution to this problem, we would have to assign utility to the
people. For example, we can assign that value based on the number of other lives
they would save. This could either be direct, such as by healing another medic so he
can assist others, or it could be indirect, such as in the scenario above where demo
dude is going to prevent the enemy from killing more of our own side than are in
jeopardy at present. Of course, there are other considerations. The three soldiers
may have the ability to do some damage as well. If we were to heal them, they could
start reaping vengeance upon our enemies… but how much vengeance? How does
it compare to what the demo man can do?
This example still comes down to a question of “how many?� Instead of stop-
ping merely at “how many lives can I save right now ?� it becomes “how many lives
will be saved eventually ?�