He wrote a number of books on Irish history as a Marxist historian.
The social and economic aspects of this movement have been stressed by Marxist historians, but its true character is elusive.
He is considered to be a Marxist and secular historian.
A new group of Marxist feminist historians is now trying to reconcile the differences, he added.
He was also known as a "progressive historian" and a "Marxist historian."
For the most part a doctrinaire approach to the study of history by Marxist historians has ebbed in its significance.
Marxist historians felt obliged to write their histories about the proletariat.
However, the problem for Marxist historians was how to tell the story of common people.
Yet Marxist historians believed that such a vital field of study couldn't be left exclusively to archeology and anthropology.
That same year, he took part in a debate among many Marxist historians.