The speaker begins with an uncomfortable observation: when you're deep in an argument, showing kindness weakens your position, because it makes the enemy harder to hate. Staying angry seems to depend on refusing to see the other side as human.
The second stanza turns inward and gets a little self-mocking. The speaker's friends see them as an old hen dancing without a head, a frantic, flailing figure who hasn't noticed that something essential is missing. It's a funny image, but also a sad one, suggesting confusion and a loss of direction.
The last stanza widens out to "us," caught between hope and fear and unsure where that leaves everyone. The final line, "running on other men's ruin," suggests that something we depend on, perhaps a way of life or a nation, is fuelled by other people's suffering. The title's "tar" hints at something sticky and hard to wash off. The mood is uneasy and guilty, edged with dark humor.