David Griffiths was a co-operative economist, which means that he studied and wrote about how people can work together to make things better for everyone. He believed that everyone should be able to get the benefits of things like food, housing, education, and health care. He thought that when everybody works together, everybody will be happier and have a better life. He studied how groups of people could work together to get these things. He also wrote about how cooperatives (groups of people who work together in a business to benefit everyone) do better than businesses that are just trying to make a profit.