Adapted from Randy CohenÕs column, ÒThe Ethicist,Ó which originally appeared in The New York Times Magazine.

I go to the same breakfast place a few times a week. I usually eat light, and typically my bill is $5 or so. This morning I had a big brunch and spent $15. But the amount of work the waiter did was the same. Did I have to tip three times as much today simply because I was hungrier?
STEVE, Portland, Oregon

I WOULD PREFER that waiters were paid a living wage, making them immune to the whims of penny-pinchers like you and me, but the system we actually have makes it customary to tip at least 15 percent of the final bill, no matter how much work is involved. You shouldn't stiff your waiter simply because you can imagine a better payment plan.

Otherwise, why limit your thrifty logic to the waiter? Why, for example, should that diner owner's profits rise if, instead of a side of bacon, you order a side of caviar? Why should a real estate agent earn more if you buy a mansion instead of a shack? Many transactions give the seller a bigger reward when the customer spends more, even when little or no extra effort is required.

Instead of thinking that you tipped too much recently, think how little you tipped all the other times. Feel better?

(The New York Times Upfront, Vol. 143, April 18, 2011)