Well that's the point, isn't it? You want your baby to learn the difference between crying when hungry or in pain or something versus crying for attention (which is usually the case).<quoted text>A 6 month old does not understand the concept of "discipline." If you hit a 6 month old baby, all you are teaching them is that if they do what they were doing immediately preceding the beating, they will get hit. In this way, you will condition your child to fear crying. It will not understand "oh, I shouldn't cry unless something is *really* wrong," it will just connect the crying with the hitting.
Babies will learn quickly that there's other ways to get the parent's attention without being bratty.