I don’t doubt that acts of aggressive violence towards children cause long term psychological problems. I’ve always doubted that corporal punishment in any form is necessarily psychologically damaging.
I’ve known too many people from my generation and especially from older generations who were spanked or whipped by their parents, and unless all of us from these generations have psychological problems I don’t know that I buy into it.
I do think the age of corporal punishment has “passed”, mostly because I think studies have shown other forms of punishment are more effective at correcting aberrant behavior. When I was growing up getting a whipping from mom (usually with a switch, aka a thin bush branch) wasn’t any big thing at all, it was mostly expected considering how much trouble we kids intentionally got in just for the fun of it. When we got caught, we took a whipping and got over it within a few minutes.
Now, kids get into trouble and their punishments are no longer physical but they sometimes last weeks (like being grounded to your room for 1 + week), it would have been unthinkable in my age to punish a child by making them stay in their bed room (except for school/other necessary things) for that length of time. “Grounding” didn’t exist back then, in pretty much every way it would have been a way worse punishment to me than getting whipped.
Part of it is also that I think kids were allowed to be a lot more independent a lot earlier, and were allowed to hurt themselves a lot more. For example I used to climb and fall down trees every day, I used to swing on grape vines in the forests and play in the creek with no shoes. I often got bruised, cut, bumped, etc. Given the rough and tumble way I lived, a whipping from mom just wasn’t a big deal. Being banished to my room for a week would have seemed hell to me back then.
I do think that anyone serious about having a reasonable discussion can differentiate between corporal punishment and a parent or adult lashing out in a violent, inappropriate manner.
As an example from my personal life, one Christmas my dad was drunk and open hand slapped me across the face for a very minor offense. It wasn’t a punishment, it was an angry, violent reaction. Even though on the whole of it my dad wasn’t a bad guy (but was definitely flawed), moments like that are etched into my mind forever. That incident “hurt” emotionally far more than the momentary sting of the physical pain. On the other hand, I can barely remember any specific incidents of being whipped for something I did wrong, because it just wasn’t a big enough deal to create distinct memories in my mind.