Etymologically, it is too bad that many of our words for being a good person go back to the offensive idea that people of higher social rank are better people than those of lower social rank. The noun "gentleman," like the adjective "noble," is an example. So let me translate Peggy Noonan's word "gentleman" to "good guy." To me, that is a powerful phrase. 

Peggy Noonan's context is the all-too-frequent mistreatment of women by men. But the elements of character she points to are just as wonderful in women. I am told by the many young people I hang around with as a professor that the word "guy" has been taking on more and more of a gender-neutral sense over time. But in the quotations, you will need to translate "gentleman" and "gentlemen" into the appropriate gender-neutral terms yourself. For example, take

A gentleman is an encourager of women.

Translated to apply to women, it says that a woman, to be a "good guy," needs to be an encourager of other women, just as a man to be a "good guy," needs to be an encourager of women. That is an important message. 

My favorite bit from Peggy's piece is this, that she attributes to the Urban Dictionary:

The true gentleman is the man whose conduct proceeds from good will . . . whose self control is equal to all emergencies, who does not make the poor man conscious of his poverty, the obscure man of his obscurity, or any man of his inferiority or deformity.

Note that this is the antithesis of standing on one's social rank. In a similar vein:

The 19th-century theologian John Henry Newman —an Anglican priest who became a Catholic cardinal—said a gentleman tries not to inflict pain. He tries to remove the obstacles “which hinder the free and unembarrassed action of those about him.” He is “tender toward the bashful, gentle toward the distant, and merciful toward the absurd. . . . He is never mean or little in his disputes, never takes unfair advantage.”

I also like this passage:

A gentleman is good to women because he has his own dignity and sees theirs. He takes opportunities to show them respect. He is not pushy, manipulative, belittling. He stands with them not because they are weak but because they deserve friendship.

However, I know there is one count on which I don't stand up very well to this standard: I am often pushy—especially for ideas. This can sometimes be hard for those around me to deal with. 

Peggy's third-to-last paragraph says something obvious and documentable:

The age of social media has worked against the ideas of decorum, dignity and self-control—the idea of being a gentleman. You can, anonymously, be your lowest, most brutish self, and the lowering spreads like a virus.

One of the places this has been documented is in Economics Job Market Rumors. On that see these three posts:

• Signalling When Everyone Knows about Last-Place Aversion: An Application to Economics Job Market Rumors
• Matthew Shapiro, Martha Bailey and Tilman Borgers on the Economics Job Market Rumors Website
• Michael Weisbach: Posters on Finance Job Rumors Need to Clean Up Their Act, Too

To be a good guy in economics, don't follow the example of the most misogynist posters on Economics Job Market rumors. There are a few other things you should do to be a good guy within economics:

1. Don't routinely assume that a female coauthor didn't contribute much to a paper. (See "When Women Don’t Get Any Credit for Coauthoring with Men.")
2. Be sensitive to the extra burdens and hurdles that women often face in economics. (See "How Big is the Sexism Problem in Economics?")
3. Tell everyone, especially women, who might need the message more, "You can do it" when they are wondering if they can do math well. (See "There's One Key Difference Between Kids Who Excel at Math and Those Who Don't" and "Calculus is Hard. Women Are More Likely to Think That Means They’re Not Smart Enough for Science, Technology, Engineering and Math.")

Literary Note: This post can be read in two slightly different ways:

1. In the phrase "good guy," put the stress on the word "guy."
2. In the phrase "good guy," put the stress on the word "good." 

I intend both readings. 

Broadening the Message: Take a look at "On Idealism Versus Cynicism," also sparked by a Peggy Noonan essay, which has a similar message, but on a broader them than gender relations.