one friend's signature

One should never increase, beyond what is necessary, the number of entities required to explain anything.

It's an interesting sentence provoking philosophical thought. Before analyzing this claim, I would like to limit "anything" to "things met in ordinary daily life", which exludes any scientific, political or social issues. Things like that will spoil the pure philosophical query here

Understandably, everyone need "some entities" to explain the world and himself or herself if one remain conscious. It's also a great thing that everything is able to be explained by a handful of "entities", and guide the action accordingly when one faces complicated siuations. Imagine that there are principles of life that guide the life just as there are three Newton's laws of mechanism that predict the motion an object. Isn't it a great triumph of human intellect?

It might grow to be an infinite list, but several most important entities that used to explain the motivation of human action includes: (from How to Win Friends and Influence People)

1. Health and preservation of life.
2. Food
3. Sleep
4. Money and the things money will buy
5. Life in the hereafter
6. Sexual gratification
7. The well-being of our children
8. The feeling of importance

If one does not want to be exhaustive about his/her list, the above mentioned entities are well-enough in explaining every day's action. One can experience limited situation compared with the sum of all human beings'. Therefore, one does not necessarily to be exhaustive in making his/her own list. Perhaps that's why the author put a constraint: "beyond what is necessary".