Economics can be both a science and an art, but before it can be an art it must be a science.
In nature, at the lowest level, economics starts as the simplest science. Human nature leads a person to experiment and the art develops.
A problem has developed in the popular theory of economics in which the art aspect and the science aspect have become confused. 'Experts' use academic language to present the economy as something that is understood (a science) and will respond to calculated efforts.
During the Cold War the conflict between the Soviet Union and the United States was usually described as an economic conflict.
The United States claimed to be defending "freedom from governmental interference in the economy". The Soviet Union claimed to be defending "freedom from exploitation". The United States tried to put the focus on prosperity and liberties (or perhaps opportunities) while the Soviet Union focused on "security through control".
Now, in 2012, the economic situation of many developed countries is shaky. It would be nice to blame the economists or the politicians, but the problem remains, and likely will get much worse before it stabilizes.
Example 1 An example of the blur between art and science.
One of the core values of colonial economics was, and is, the manipulation of exchange rates to promote the home economy. An incompatible core value was, and is, the promotion of stable relationships with other countries.
Common sense, as well as the science aspect of economics, says an hour is an hour anywhere, a cup of grain is a cup of grain anywhere, etc. This is a straightforward principle that starts with balance. There are no future repercussions that have to be anticipated.
However economic artists, in the tradition of small children making masterpieces on the wall with feces, had to try to outdo the perfection of simplicity. Economics became a political tool, a weapon to use against the less developed. Adding to the obscenity are people, even today, who justify this by claiming superiority. We are superior. They are not. Therefore we will prosper at their expense. It is a value system that offends nature and nature itself corrects it. There we are today.
[The United States still has a higher apparent gdp than China. The Chart is to show China's trend.]