  Is there a lesson here for resolving moral problems through social interactive reasoning? Mercier and Sperber cite the abolition of slavery by the British Parliament in 1834 after some fifty years of debate at all levels of society. Abolitionists were at first in the minority. They asked how Christian moral norms of brotherly love and equality before God could be reconciled with enslaving Africans. Those defending slavery retorted that Africans were less intelligent and lacked integrity, but these claims were contradicted by the eloquence and evident moral character of former slaves who addressed public meetings and by Christian witnesses who had known slaves from personal experience. The economic consequences of abolition were also debated. In the end the majority of public opinion changed through discussions that permitted careful examination of diverse points of view from different parts of society over a long enough period to establish credible evidence about the negative consequences of slavery compared to the likely positive effects of its abolition.