Summary
This piece briefly summarizes the utilitarian mindset for making a difference in the world.
Feelings
Some organisms (people and many animals) experience emotions. Denote as "positive emotions" (or "utility") those feelings that an organism would prefer to experience. Examples might include pleasure, happiness, satisfaction, love, awe, beauty, and "meaningfulness." Call those emotions that an organism would rather not experience "negative emotions" (or "disutility"). Examples might include pain, sadness, depression, anger, and hopelessness.
Utilitarians care about these emotions because the emotions matter to the organisms that experience them. Of course, not all emotions matter equally, and it would be nice to have some way of capturing the fact. Utilitarians do this by assigning numbers to different emotions in proportion to their importance. Of course, this process will be inexact and sometimes arbitrary, but unless we want to abandon the goal of capturing differences in magnitude between emotions, we have little alternative.
Example. Suppose Alice enjoys watching TV but finds it more meaningful and rewarding to spend time playing with her kids. Let's assign the number +2 to the pleasure of watching an hour of TV and +10 to the satisfaction that Alice feels when she spends an hour with her kids.
Note that the ratio of these numbers is 10/2 = 5. In assigning rough magnitudes of utility to two different experiences, A and B, it can be helpful to ask, "How many times would I have to experience A in order for it to equal one experience of B?" The answer to that question gives the ratio of the utility of B to the utility of A. In the case of the Example, the answer is 5, because 5*2 = 10.
Changes in utility
Once we assign numbers to different outcomes, we can look at changes in utility that result from actions.
Example. Alice makes a decision to spend an hour with her kids instead of spending that hour watching TV. Her utility increased from 2 to 10, meaning that her action caused a change in utility of +8.
We can also look at changes in "aggregated utility" over groups of organisms:
Example. A deer finds a lush patch of grass and begins to eat it, giving the deer a utility of 5. Two other deer come along and steal the food, which increases the utility of each of those deer from 0 to 4 but lowers the utility of the original deer to 2. The total change in aggregated utility is
Deer 1: (final utility) - (initial utility) = 2 - 5 = -3
Deer 2: 4 - 0 = 4
Deer 3: 4 - 0 = 4
Total: -3 + 4 + 4 = 5.
Why it matters
All of this may sound abstract and fanciful. After all, there are many organisms in the world enduring experiences that are almost indescribably awful. How can utilitarians be so callous as to play around with made-up numbers? The fact is, though, that some actions will do more to relieve that suffering than others. It doesn't help those in pain for us to take the first action that comes to mind or do something because it makes us feel good. What helps those in pain the most is for us to systematically analyze the consequences of our actions and make tough decisions about some things being more important than others. The toy examples developed here were merely intended to illustrate that process.