Ed Miliband hoped to make Labour the ideas party as he introduced Harvard University political philosopher Michael Sandel.
Prof Sandel was the star guest at the Labour Party conference, setting out his theories about the impact of markets on society.
Prof Sandel used examples including people who allow themselves to be tattooed with advertising to explain how social conventions were being eroded as a result of market pressure.
He said: "We have drifted from having market economies to becoming a market society.
"The difference is this: a market economy is a tool, a valuable and effective tool, for organising productive activity.
"Market economies have brought prosperity and affluence to countries around the globe.
"A market society is different. A market society is a place where almost everything is up for sale, it's a way of life in which market thinking and market values reach in to domains of life previously governed by non-market values."