Each of my three kids have been hauled to the bathroom for a swat after a calm warning to nip a fit in public about one time each(actually-my son twice, and my third needed a few hard pinches in addition to a swat or two). To put that in context, I have taken all three of my kids (6,4 and 2 1/2) with me to the grocery store EVERY WEEK since the first was BORN and ALL other errands because my husband always travels. That's about 300+ trips to grocery store ALONE not including all other errands. So a few effective discipline episodes in public (it will only be a few if you are consistent at home) is a very small price to pay for having kids who behave well and don't throw fits-thus enabling me to function and accomplish things, We have fun together out and about every day. The book Back to Basics Discipline by Janet Campbell Matson has great advice that works. If he's just starting this, it's the easiest time to nip it for good. My kids all sat in the cart until they could walk nicely by the cart. No other option. Just one warning. No anger. And no one fights the car seat. Don't allow it. He'll be happier if you don't.