Man is an empirical being. We have been given our senses to learn things through our interaction with the world. Many philosophers try to use this as the staple to their thought, but man is not simply a body. We have a soul.
This is the notion that we begin to understand once we begin studying Pope John Paul II's Theology of the Body.
Our Lord, Jesus Christ, has given us certain Sacraments so that we may experience God within the world through our senses of the body.
The Catechism tells us that Man "needs signs and symbols to communicate."(no. 1146)
In the market economy, we have a sign that helps us to communicate. It allows us to know who needs what resource more than another in comparison with other individuals.
There is not enough information within the world for us to know how much of something or another any individual but ourselves need. Preferences are known only to the individual self, unless he tells another. Even then, his preference will change from one moment to the next and the person he had told will no longer know for a fact what the other needs.
If conventional communication such as speech is not suitable for us to notify others of our ever changing needs, how does man interact without conflict?
The answer is prices. Prices are the sign within the market economy. When one purchases an apple he sends a message to others that there is one less apple in the world. The prices of all the other apples would then change to signify the use of an apple. In this format, man can successfully interact without conflict.
What other signs help us communicate? What other symbols allow us to socially cooperate with one another peacefully?