"So... you're saying it was wrong of my father to give my brother the belt after he chased me and my sister around the house with a butcher knife?"
Yeah, I am. In case you haven't been around any normal, well-adjusted children, kids who aren't already screwed up don't generally tend to chase their siblings around with knives. Perhaps your brother was reacting to the abuse he suffered from your father?
While I don't agree with spanking, if a parent is too lazy to figure out how to disciple without spanking, I'd prefer one or two open-handed swats on the butt to no disciple at all. That being said, an object should never, EVER be used to strike a child. Using an object makes you unable to judge how much force you're putting into the blow.
And, whether you like to admit it, spanking does cause more harm than good if you're using it to discipline a child. A 2010 study "Mothers' spanking of 3-year-old children and subsequent risk of children's aggressive behavior" in the American Academy of Pediatrics Journal concluded:
"Despite American Academy of Pediatrics recommendations to the contrary, most parents in the United States approve of and have used CP (corporal punishment) as a form of child discipline. The current findings suggest that even minor forms of CP, such as spanking, increase risk for increased child aggressive behavior. Importantly, these findings cannot be attributed to possible confounding effects of a host of other maternal parenting risk factors."
I imagine the affects on older children aren't any more positive.
ETA: I found a fairly interesting site on spanking- http://www.parentingscience.com/spanking-children.html