Hannah Arendt, answered from the texts and cited to the page.
Compassion, pity, conscience are private virtues. Compassion is the suffering with another that closes the distance between persons in the silent intensity of shared affliction; pity is the sentimentalized public form that compassion takes when it is deployed in the political space, where it absorbs the plural suffering of many into the spectacle of suffering for the contemplation of those who would deploy it; conscience is the inner voice of the two-in-one dialogue, the conversation with oneself that thinking is and that bears on the question whether one can remain a friend to oneself after what one has done.1
The analytical question is what happens when these private virtues are imported into the political space. Robespierre's pity for the suffering masses, transmuted into the political principle of the Terror, is the case in which pity entered politics and produced catastrophe. Solidarity — which is not a feeling but a political principle — is the political alternative to pity: solidarity preserves the plurality of those it joins, where pity dissolves that plurality into the suffering mass.2
The same analysis applies to compassion (which the public space cannot bear) and to conscience (which is the activity of the solitary self with its two-in-one and which cannot itself ground political judgment, as Eichmann's case demonstrated). The question whether the analysis holds across all its applications, and especially whether the "Civil Disobedience" dismissal of Thoreau-style individual conscience underrates what conscience does in political resistance, is a question the texts press but do not resolve.
Terminologically speaking, solidarity is a principle that can inspire and guide action, compassion is one of the passions, and pity is a sentiment. Robespierre's glorification of the poor, at any rate, his praise of suffering as the spring of virtue were sentimental in the strict sense of the word, and as such dangerous enough, even if they were not, as we are inclined to suspect, a mere pretext for lust for power.On Revolution, pp. 85–86
In this sphere of intimacy, compassion became talkative, as it were, since it came to serve, together with the passions and with suffering, as stimulus for the vitality of the newly discovered range of emotions. Compassion, in other words, was dis- Pity may be the perversion of compassion, but its alternative is solidarity.On Revolution, p. 84
This is the area of the corpus that has caused the most philosophical bafflement after Eichmann. George Kateb's Hannah Arendt: Politics, Conscience, Evil (1984) is the locus classicus of the unresolved-tensions reading: Kateb argues that the analysis of pity in On Revolution, the contrast between compassion and solidarity in The Human Condition, and the dismissal of individual conscience in "Civil Disobedience" stand in unresolved tension with the moral-thinking analysis in "Thinking and Moral Considerations" and The Life of the Mind. Margaret Canovan's A Reinterpretation Chapter 5 names the tension as genuine and defends the analysis as comprehensible only against the totalitarian-era backdrop. Shadia Drury and other critics have been sharper. Benhabib in The Reluctant Modernism reads conscience in a more dialogical-deliberative direction. The tension is real. I did not resolve it in my lifetime; The Life of the Mind was working toward a resolution that the Judging volume would have completed, and that volume was not written before I died. The texts as I left them carry the tension without resolving it.