For those inDUHviduals that don't seem to have enough functioning brain cells to figure this out on their own, here is a Free Clue:
You should turn your lights on when the weather is bad (rain, fog, snow).
Sure, maybe you can see "okay", but turning your lights on -- all the way, not just your parking lights -- means that it's easier for other people to SEE YOU. Now, here's the tricky part so you need to pay attention: if other people can SEE YOU, then they're a lot less likely to do something nonsensical like pull out in front of you. This means that you're a lot less likely to get into an accident. To make it even easier for you, try to remember that LIGHTS ON = ACCIDENTS OFF.