BRICs, the now familiar term for Brazil, Russia, India, China and the growth of their economies and influence, have formalized their club and extended their reach by inviting South Africa to join. But do their meetings and joint statements really allow them to punch above their individual weight? What do these countries share beyond a common interest in bolstering their global clout?

The most durable thing about the BRICs is the acronym itself. They cannot be ignored — emerging markets accounted for two-thirds of global economic growth over the past five years, a figure that could rise to as much as 75 percent by 2015. But combining individual countries into classes based on catchy acronyms adds neither influence to their groupings nor insight into their futures.

There are four main reasons why the BRICs will never function as a single coherent interest group.

First, we often say BRICs when we really mean China. In the post-World War II era, the Group of 7 major industrialized countries set the international agenda, and the United States was the driving force. But China’s dominance of the BRICs is even more pronounced. With a G.D.P. of $7.3 trillion, the Chinese economy is the second largest in the world — and larger than all the other BRICs put together.

South Africa’s economy is roughly equivalent to that of China’s sixth largest province. Developments inside China — from its resource appetites and cyber capacity to its political and military might — will drive the actions of the other BRICs. Russia, India and Brazil will be responding to China, both cooperatively and antagonistically, much more than they will coordinate with it.