Speaking out: is it an act of courage?

I used to define justice as a way of protecting one’s rights: the right to speech, the right to marry, and the right to believe in a religion.

Aristotle’s view of justice, on the other hand, has taught me that justice can be accomplished in two ways: justice can be either achieved by settling a compromise between two or more people to create peace and harmony within the society, or it can be achieved by committing a courageous act due to one’s integrity and moral upbringing – with no rational thinking behind such act.

Can "speaking out" be a form of a courageous behavior?

In Wal-mart one day, I was standing in the line to get to the cashier when a five-year-old boy started to bawl on the floor. His mother, looking very stressed, started smacking her son to quiet him down, but this only made him scream louder. These weren’t just casual smacking - these were legit backhand slaps that would have left bruises even on me.

So I stand there, and I contemplate my options. People around me are already choosing to ignore it by looking the other way. I could either (a), also ignore it and tell myself that saying anything wouldn’t really stop her from doing the same thing again or (b), I could intervene and ask her if such actions were truly necessary. I decided to choose the latter, only because I was so disgusted that it would have been completely immoral for me to not say anything and act like what she was doing was normal. Middle school has raised me to understand that bystanding and bullying are without a doubt injustice.  And this woman can argue that she was disciplining her son. She can also claim that she was also raised that way, and it is only natural for her to raise her kids the same way. But in my argument, this is how bystanders behave. It is shocking enough that domestic violence happen in the curtains of people’s home, but it is even more shocking that when such behavior that is expressed in public, people feel that it is right to ignore it, rather than intervene, because it is not their business.

Of course, I questioned whether it was necessary for me to have even said anything. After all, perhaps the woman was only doing what she knew. But then, I remember that this is how domestic violence in China plays out. Majority of population in China have domestic violence in their homes. The law declares domestic violence injustice. However, in the mindset of the society, if a woman is beaten by her husband, she "deserves" it because she was either disloyal or irrational to her husband. There are less reports on domestic violence because most citizens in China feel that it is not their business to get involved in "family matter". 

So this is what I ask: is speaking out only justice for yourself?