Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Polemical, Anti-Establishment, Ironic, Cynical but Hopeful
Polemical, Anti-Establishment
For Brecht, it makes sense to say his tone is "anti-establishment." After all, he writes in protest against World War II and the rise of Nazism in Germany. And Brecht's polemical take on the traditional virtues of war and religion—valor, self-sacrifice, loyalty, etc.—is loud and clear in Mother Courage. Let's take a look at a few lines from the play:
MOTHER COURAGE: They'll never beat him, and why, his men got faith in him. Seriously: To go by what the big shots say, they're waging war for almighty God and in the name of everything that's good and lovely. But look closer, they ain't so silly, they're waging it for what they can get. Else little folk like me wouldn't be in it at all. (III, 212-217)
When Mother Courage starts to talk "seriously," we know she's about to say something important. And what she's saying is something that comes up again and again in this play, both in what the characters say and in the actions portrayed.
Courage is talking about the discrepancy between what leaders say about war, and the reality of why war is fought. It's "little folk" like her, who join the war because they think they'll profit from it, that really understand their leaders' motivations. Why? Because "the big shots" start wars for the same reason the "little folk" join them: to make money.
Lines like this one, which juxtapose the hypocrisy of the war-waging establishment to the candor of the lower classes, can be found throughout the play. But just because Mother Courage says it, doesn't mean she's right, or that we're just supposed to agree with her. What this line does is establish a polemical tone. Its purpose is to get us to think about controversial topics, like the idea that wars are really all about money and profit.
Ironic, Cynical
To say that a cynical tone prevails in Mother Courage is an understatement. It's practically a treatise on cynicism.
When we talk about a cynical tone, what we mean is a general pessimism and lack of reverence toward things traditionally thought to be good and virtuous. Now, this can also be polemical and anti-establishment, as in the previous example. But polemical moments in Mother Courage tend to be more "serious," whereas Brecht's cynicism often comes across through the use of humor and irony, even when the take-home point is the same. Take the cook's speech about the Swedish king, in Scene III:
THE COOK: Just what I say, your brandy's first rate, I weren't mistaken in your face, but talk of the king, it cost the king dear trying to give freedom to Germany, what with giving Sweden the salt tax, what cost the poor folk a bit, so I've heard, on top of which he had to have the Germans locked up and drawn and quartered 'cause they wanted to carry on slaving for the emperor. Course the king took a serious view when anybody didn't want to be free. He set out by just trying to project Poland against the bad people, particularly the emperor, then it started to become a habit till he ended up protecting the whole of Germany. They didn't half kick. So the poor old king's had nowt but trouble for all his kindness and expenses, and that's something he had to make up for by taxes of course, which caused bad blood, not that he's let a little matter like that depress him. One thing he had on his side, God's word, that was a help. Because otherwise folk would of been saying he done it all for himself and to make a bit on the side. So he's always had a good conscience, which was the main point. (III, 189-207)
As we'll see, the underlying issue in the cook's speech is nearly identical to what Mother Courage says when she starts to talk "seriously" about war, money, and religion. In other words, the idea is that our dear leaders wage wars in the name of highfalutin' concepts like God and freedom, only to cover up the fact that they're really in it for their own good.
The difference here is that the cook doesn't say this outright; in fact, what he says implies just the opposite. This is what we mean by ironic. He seems to be taking pity on "the poor old king," who only wanted to free all those Catholics from their "slavery." He seems to be justifying the king's actions: those darn Catholics just don't want to be free, so of course the king had no choice but to keep raising taxes on his own people to fund the war. Finally, the cook says it's lucky the king was on God's side, because otherwise it might look like he only went to war to raise taxes.
Of course, we don't think this is what the cook really believes. Right? Well, if we're not sure, Mother Courage is there to clarify things in the next line. She gets that the cook's actually taking a jab at the king when he seems to be defending him:
MOTHER COURAGE: Anyone can see you're no Swede or you wouldn't be talking that way about the Hero King. (III, 208-209)
And later, he agrees with Mother Courage when she starts talking "seriously" about war-wagers being in it for the money (III, 218). We see that the cook really does mean to say that the king only went to war to raise taxes. He doesn't think the king gives a hoot about "God's word." He's being ironic, expressing his opinion using terms directly opposed to what we would expect. And while irony is not the same as cynicism, moments like this one definitely add to an overall cynical tone in Mother Courage, by implying that even the truth can't always be stated plainly, and has to be masked using irony.
...But Hopeful
We're not letting Brecht off so easy. Mother Courage would bore most of us if it didn't occasionally exchange its polemical, ironic, cynical tone for a little bit of hope. And that's where Kattrin comes in, Mother Courage's mute daughter.
If anyone is reliably earnest in this play, then it's Kattrin. For one, it's hard to make ironic or polemical statements when you can't speak. But Kattrin's actions can and do communicate her genuine sympathy with the suffering of others, her desire to love and be loved, and ultimately, her remarkable spirit of self-sacrifice.
Even when everyone around her has grown cynical about freedom, faith, or love, and even as a victim of war violence herself, Kattrin doesn't seem to have lost her innocence. We also sense this in the words Mother Courage uses to describe her, when she refuses to abandon her daughter in order to start a business with the cook:
MOTHER COURAGE: Cooky, how's she to pull the cart on her own? War scares her. She'll never stand it. The dreams she must have…I hear her nights groaning. Mostly after a battle. What's she seeing in those dreams, I'd like to know. She's got a soft heart. Lately I found she'd got another hedgehog tucked away what we'd run over. (IX, 74-79)
Now, words like these portray Kattrin as innocent. She's scared of war. She's compassionate. She likes hedgehogs. But in the broader context of the play, they also serve to alter its tone. Hearing Mother Courage say this makes us think that people in her world might not be so bad after all. When everything else is about profit and power, at least Kattrin's character suggests that hope, innocence, and true self-sacrifice can still exist, despite it all.