Allow me to reach forth to the realm of Platonic forms and grab therefrom a type of experience you are likely to have had or witnessed if you’re female.
You’re at a party. It’s full of smart, interesting people because you are smart and interesting and like seeks like. Over by the olives with little sticks in them, your good friend, Dr. Astronomy is talking with another woman about some super science shit related to her field of expertise, astronomy. You sidle up to listen because your friend Dr. Astronomy is not only one of the smartest people you have ever met (and that says a lot, considering the company you keep, you smartie-pants), but also has a special knack for taking her deep expertise in a subject and expressing it in terms both accessible and entertaining.
A Dude comes by to grab one of the olives on a stick, and notices three ladies gabbing about science shit, so he has to join the conversation and add his unique male perspective. It’s a party full of smart, attractive people, so of course you welcome A Dude into the conversation, thinking that it will move the discourse forward in a philosophically embiggening direction.
Instead, A Dude proceeds to talk down to Dr. Astronomy about black holes and Pluto and all sorts of stuff. You feel embarrassed for A Dude. He probably doesn’t realize that Dr. Astronomy is an expert in the subject, and she is probably too polite to mention it directly. Luckily for everyone, the other woman in the conversation is a bit more straightforward and mentions to A Dude that we’ve been over this topic and Dr. Astronomy happens to be pretty knowledgeable in it.
Undeterred, A Dude continues to dominate the conversation, shutting out the very interesting Dr. Astronomy with his uninformed opinions. The ladies then are left only to exchange a knowing look, and announce en masse that they must go take a leak. In the quiet of the restroom, they may continue their science talk undisturbed. (This is what actually happens in the Platonic form of ladies’ rooms)
What just happened? That’s mansplaining. In our Platonic form of mansplaining it’s really obvious that the dude was talking out of his ass, and talking down to and over a woman who is actually more knowledgeable than him. Sometimes it’s a little harder to recognize. What if both people happen to be about equally knowledgeable? Still mansplaining if dudes dominate the conversation.
Mansplaining gets particularly silly when women are talking about their personal experiences and then men come and tell them that they are wrong. That’s why a lot of groups for professional and political advancement of women don’t allow dudes. It only takes one mansplainer to derail a good conversation.
For more on mansplaining, I highly suggest Zusa’s post You May Be a Mainspainer If…