Debate has raged as to whether rising commodity prices owe more to the actions of speculators and less to an imbalance in supply and demand. Speculators have not come out well in this debate - not surprising in light of the food riots in developing nations and fuel protests in developed ones.

But amid the often heated exchanges about responsibility for booming commodity prices, few stop to define what they mean by speculation. Perhaps it suits some of the participants not to have a clear definition. Yet if this debate is to have merit, we must agree on its terms.