Needham argued, and most scholars agreed, that cultural factors prevented these Chinese achievements from developing into what could be called "science". It was the religious and philosophical framework of the Chinese intellectuals which made them unable to believe in the ideas of laws of nature. More recent historians have questioned political and cultural explanations and have focused more on economic causes. Mark Elvin's high level equilibrium trap is one well-known example of this line of thought, as well as Kenneth Pomeranz' argument that resources from the New World made the crucial difference between European and Chinese development.