the colonized. The exploitation of a colony’s natural resources and people, the global slave trades, and the suppression and elimination of indigenous peoples and cultures are as much the products of colonial rule as its more positive outgrowths. Historical and policy research also shows that, despite the improvements to economic growth and long-term health that resulted from colonial rule, many post-colonial nations’ current economic and political challenges, including corruption, political instability and violence, and low economic productivity, are directly connected to colonialism and the geopolitical status quo it created.

Ultimately, a historian’s interpretation of colonialism as a positive or negative historical development depends on the subject or point of emphasis, although most historians do agree that colonialism’s negative outcomes far outpaced its positive ones.

Suggested Reading: Jared Diamond, Guns, Germs, and Steel: The Fates of Human Societies (1999), Adam Hochschild, King Leopold's Ghost: A Story of Greed, Terror, and Heroism in Colonial Africa (1999), A. Adu Boahen, African Perspectives on Colonialism (1989)

This question is of course a matter of opinion, and the answer may well depend on one's perspective. Certainly, some who would argue that imperialism had significant positive results might point to several results, including the eradication of some diseases by Western initiatives, the introduction of some Western ideas and technologies, and perhaps even that some colonial peoples, usually favored elites, flourished and became quite wealthy under European rule. 

But ultimately, I would argue that the effects of imperialism were hardly a net positive for former colonies. Many colonies were gained and maintained through warfare and violence as indigenous peoples resisted European rule. European imperialists tended to create divisions where none had previously existed by favoring one group over another for positions in local government and other privileges. This created animosities that persisted well into the post-colonial period, sometimes with disastrous consequences (like the Rwandan genocide). 

Imperialism also typically involved the expropriation of wealth, usually in the form of natural resources, from people around the world. Lands were put to growing cash crops, forests were cleared, mines were worked, all for the profit of the imperialist power (or often private businesses granted rights within the colonies). This arrangement also persists into modern times in many countries around the world. Imperialism also tended to involve attempts to impose Western culture on peoples around the world, to the detriment of native culture. Finally, imperialist powers often redrew the maps of Asia and Africa in ways that did not really reflect the ethnic realities on the ground. So people with longstanding grievances with each other were crammed within artificially-imposed borders even when colonies gained independence. Throughout Africa and the Middle East, this has led to violence and civil war. So overall, I would suggest (along with the majority of academic historians) that whatever positive outcomes may have resulted from imperialism, it ultimately had a negative effect on the peoples caught up in it.