A great deal of economic growth is required in order to increase prosperity and spread it more widely. The question economists ask, then, is how best to attain economic growth.
There have been two approaches to attaining growth. One has been through governmental planning and bureaucratic management. This is called socialism. The other is by leaving economic actors to make their own decisions. This is a market economy or capitalism. Market economies work much more efficiently than managed ones, and economists can show why resources are more efficiently used when free transactions set prices. What to produce, how much to produce, and at what price to sell are decisions to be left to the economic actors.