Most people, in the US, cut with a fork in their left hand a knife in their right, then set the knife down and move the fork to their right hand. I would assume that’s why you have the place settings with the fork on the left and knife on the right, that’s where you’re going to need them first.
ETA as Bozuit said and my Australian uncle confirmed, in other countries, they just leave the the fork in their left hand and eat that way. Perhaps the fork on the left is a holdover from that.
Formal table manners dictate that you hold the fork in your left hand and the knife in your right, using the knife to cut your meat. Since most people are right-handed, they want to use their right hand for this. If you’re American you then put down your knife, transfer the fork to your right hand, and use the fork to take a bite. If you’re European, you just use the fork in your left hand to take a bite, without switching the fork from hand to hand.
Tines MUST be down. It’s the only way! Otherwise they behead you.
I’m about the only person I know who eats UK-style; everyone else does the frequent utensil-switching-from-hand-to-hand thing, which I find deeply illogical. Or use the side of the fork to cut up food, which is also weird.
Unlike zoid, here in the Midwest I very rarely see anyone using left-hand fork style eating.
Another American who can’t imagine Americans eating in the British style. Maybe 1 out of 50-100.
I’m sure that if you went back to Britain in the 1600’s, everyone who had a fork and knife used it like they do today–fork in left hand, knife in right. Never transferring the fork to their right hand.
It would be interesting to know when the American style of switching hands occurred(and WHY).