The Difficulties of Mercy: Reading Thomas Aquinas on Misericordia

In the Questions on charity in the ST (2a2ae, qq. 23-46), Aquinas considers at length the vices opposed to charity, omitting altogether any Question on a vice opposed to mercy. What does the omission reveal about mercy and its difficulties? First, I reject ready-to-hand explanations of the omission. Second, I consider the relation between mercy and compassion, showing that for Thomas the primary impediments to compassion are less vices than psychological forces irreducible to any single vice. Third, I turn to a different set of obstacles to mercy - acts that can arise from compassion, but do not help (and often harm) the person in need. Given these difficulties, how can Thomas take the practice of virtuous mercy to be generally possible? I conclude with a discussion of suffering and the gift of wisdom.