When you ask an ordinary person what the cause of the Irish famine was they will most likely say it was a failure of the potato crop. This is only partly true. The most important questions to ask is why were millions depending on a crop that was not even indigineous to Ireland? And why were the landowners exporting vast amounts of pork, beef and grain when the people were starving?
Ireland in fact produced enough food to feed 18 million people during the 1840s. However the market dictated that that the supply went where there was "demand". When capitalists harp on about supply and "demand", demand only includes those with money. The poor all over the world have many demands and needs but these will always be ignored by the capitalists.
The role of the state under capitalism is to protect private property. That is why the police and army protected the landlords and hung or deported those who tried to "steal" food. The fact is the only thieves were the landlords themselves. The capitalist robber baron will always use coercive methods to dispossess the people and then create laws to legalise their theft.
What Ireland needed in the 1840s was a mass revolution which placed the people in control of the lands. A planned economy could then be formed to produce according to people's needs and not for profit.
It is disgraceful that the history books are constantly being re-written so that capitalism and the capitalist state seem blameless. The revisionists wish us to believe that this was just an accident or an unavoidable tragedy. Maybe the capitalist "historians" will acknowledge the state could have done more to provide relief but that is all. It is inconvienient for the capitalists to acknowledge that the "free market" is the main cause of the saddest and most shameful part of irish history. That is why they will blame the potato. As George Orwell wrote "Those who control the present control the past".
It is also interesting to note that famines in non-capitalist countries are played up for the purposes of propaganda. Take the famine in China circa 1960 which is the greatest famine in history (although proportionately was not as bad as the Irish famine). This famine is exploited by capitalist historians for ideological reasons. While this famine was partly due to bad planning and naive farming practices enforced by the Party, the severe weather that destroyed many crop harvests are never reported by the capitalist historians.
Famines in capitalist countries are caused by natural disasters, famines in "communist" countries are caused by political theory.