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Whats the difference between caring and only pretending to care?

Rachel Brosnahan and Oscar Isaac in The Sign in Sidney Brustein’s Window.

Of course theres nothing new about the problem of intention and action.

So, to Iriss distress, up goes an endorsement.

The plays dialogue teems with of-the-moment concerns and references to everyone from Castro to Camus.

How best to protest the anti-gay sex laws?

How to make peace with action in the grip of existentialism?

What about the possibility of nuclear annihilation?

Also, is it selling out to act in TV commercials?

Yet Hansberry resists a structure as simple as that.

Hansberrys play holds up people like Mavis, Sidney, and Iris to the light for inspection.

Whats to be done with these selfish, self-regarding purported allies?

Then, like someone cutting open rough-hewn rock, she sets the actions of her plot upon them.

The play is harsh, but as it pares its hero down, it reveals something hopeful.

The Sign in Sidney Brusteins Windowis at the BAM Harvey Theater through March 24.