From a recent interview by Stephen Sackur of the BBC with Stuart Russell. I liked Professor Russell's response.
(starting at 3:22 in the download; transcript edited somewhat)
How I would prefer the Encino article to read: Although I suspect such an edit would be reverted, if for no other reason because the Galleria is in Sherman Oaks, just barely outside of Encino.
When I was 20 years old, I drove an old car that was still titled, registered, and insured in my father's name.
A friend asked to borrow the car. Correct would have been to say that it was not mine to lend but it was a friend who had been very helpful to me and I wanted to reciprocate. I was young, with all the ability to make poor decisions that comes with youth. I said OK.
When I got the car back one of the doors was dented. He said it was a hit and run by a city bus. The way he described the accident didn't seem consistent with the damage but what could I do.
I told my dad I was driving the car at the time. I hated telling that lie but it would not have gone well if he knew I had lent the car to someone. He had explained to me that it's the car's owner who can be sued for all they're worth if injuries are serious enough to max out their insurance.
As sour an experience as that was, at least no one got hurt. The car was old enough that it wasn't worth repairing the dent.
I recalled this incident yesterday morning for who knows what reason. Then in the evening I was driving on California route 14 a little south of Mojave, at about the speed limit (65 mph). Someone was wandering around on foot right ahead of me. This is not normal. Occasional rabbits and birds in the middle of your lane on freeways in the desert, yes; pedestrians, not usually. It was dusk, they were wearing dark clothes, and made no effort to get out of my way. My headlights were on but still the person wasn't conspicuous from a distance. I had time to slow down and change lanes but wow am I glad I had my eyes on the road.
There's no way to define left/right without reference to a physical object that exhibits the convention. merriam-webster.com defines left as "of, relating to, situated on, or being the side of the body in which the heart is mostly located".
You could try to define left in terms of the curvature of an exponential function. While driving on a road whose path follows the graph of y = 2x, headed in the direction toward higher values of x, you turn left continuously. Problem is, that depends on the layout of Cartesian coördinates, which place the positive y axis to the left of the positive x axis. That's arbitrary; we could just as easily use a coördinate system with the y axis directed the other way.
dictionary.com defines left as "of, relating to, or located on or near the side of a person or thing that is turned toward the west when the subject is facing north". Implicit in that definition is that the person is upright. When I stand on my hands, west is to my left when I'm facing south.
That definition makes reference to west and north, so how are those defined? North is "a cardinal point of the compass, lying in the plane of the meridian and to the left of a person facing the rising sun." Left is defined in terms of north and north is defined in terms of left.
Let's say there was an episode of Sesame Street that taught kids left and right by reference to visual examples. Imagine an extraterrestrial civilization receives the broadcast. Our TV systems scan lines left to right, an arbitrary convention; without knowing that, aliens could just as easily render the frames in mirror image.