In Book 2 of Nicomachean Ethics, Aristotle makes a big deal of emphasizing that virtue is found in the middle between excess and deficit. For example, courage is intermediate between cowardliness and rashness.
Apparently, plenty of people have criticized this notion by noting that it doesn’t really doesn’t do us much good when deciding how to be virtuous. For example, JL Mackie wrote that from Aristotle:
We learn the names of the pairs of contrary vices that contrast with each of the virtues, but very little about where or how to draw the dividing lines, where or how to fix the mean.
I agree. Aristotle doesn’t really do a great job of providing any insight as to why virtues tend to exist as a medium between vices. So let me give it a try.
The reason virtues exist as an intermediate between vices is due to the relationship between virtue and base desires. Going back to the courage example, the relevant base desire is pain avoidance (as Aristotle himself discusses in more detail later on).
Obviously, pain avoidance is can be good for survival. Painful things are often the kinds of things that can kill us, so avoiding them is generally good. Therefore, suppressing this instinct completely seems like a strategy doomed to failure. However, the pain instinct is imperfect, and in some cases our chances of survival (or reproduction) are improved by ignoring our pain instincts.
Courage can be defined as the ability to suppress our aversion to pain (or risk of death) when it is appropriate. In other words, a virtue is like a filter on our baser instincts. The purpose of a filter is to separate the good from the bad. If you view virtues as filters on base instincts that are generally effective, then it becomes clear why they can be either too aggressive or not aggressive enough.
In fact, a lot of consciousness can be understood as a filter. One of the first things that turned me on to this idea was a study that showed how LSD works. LSD doesn’t create new impulses. It shuts down parts of the brain that usually filter existing impulses. So it allows us to access a more primal, pre-filtered state.
Ok, so the only other thing I want to say about book 2 is that it is the origin of what is known as the Anna Karenina Principle. Here is Tolstoy’s version:
All happy families are alike; each unhappy family is unhappy in its own way.
Here is Aristotles original version:
Men are good in but one way, but bad in many.
