. Not even things like murder and rape are objectively good or evil, and if you believe otherwise, then prove it with the "rationality" that you hold so dear.
Try Kant.
Insofar as the British Raj goes one needs to consider it both against contemporary morality and modern morality, and realise that what was moraly acceptable changed over the 200 or so years the British were invoved in India.
Based on contemporary morality the British Raj was fairly bad, although perhase better than most other colonial ventures. The things they contributed to the sub-continent were not worth the price in blood and freedom. The reasons for British involvement are also morally dubious at best - few people in modern time consider the protection of trade to be a legitiamte reason for war and conquest.
However, based on the morality of the time (even excluding such self serving ideas as bringing 'civilisation') the British Raj was far more morally sustainable. It certainly provided a measure of stability and law to an area that was notably missing in both prior to their arrival. Whilst massacre and atrocity certainly occured neither could be considered as official policy, unlike in many of the states prior to British conquest. The only case I know of where massacre was a deliberate policy used to terrorise a population was in response to the Sepoy Mutiny, which was in response to atrocity and massacre. IF you consider British authority to be legitimate and IF you consider the restoration of law and order to be a priority then the British actions in that case are defensible.
The contemporary moral case for empire gradually eroded throughout the late 19th and 20th centuries and led to the British leaving India semi-voluntarily, which is to their credit, along with a gradual shift in British attitudes to opposition to their rule, over that time period.
As far as the Bengali Famine of 1942, the only one I have done significant reading on, it was not caused by deliberate policy, but rather through poor governence and incompetence as well as a deeply callous attitude to the lives of Indians. The famine was a direct result of poor harvests in Bengal and was compounded by the loss of Burma, which was the region the British usually turned to for reliable food surpluses to alleviate Indian famines (something they usually did do). Whilst the British Empire did have significant food surpluses that could be moved to Bengal to mitigate the famine (and which did indeed eventually occur) the administrators made the descision that the war effort was more important than the lives of the people of Bengal. This brutal descision is to the enternal shame of the empire, but it was not a deliberate attempt to inflict a famine (contrast with Hunger Plan Ost) and needs to be understood in this light. I would, however, say that it does illigitamise British rule - if you occuply a place for the (supposed) benefit of the inhabitants then allow them to starve enmass you have clearly failed to meet your own stated requirements.