--Boris
I think if the person is large enough to need two seats, they should pay for it or take alternate transportation.
Let's look at this, using hypothetical situations, kind of like parables.
What if you were sitting on a crowded bus, and a little old lady boarded, but couldn't find a seat?
What if you were sitting on a crowded bus, and a pregnant lady boarded, but couldn't find a seat?
What about a pregnant lady, if you know that she conceived "out of wedlock?" It is "her fault," so she should pay for her bad behavior (by standing up on the bus).
What if the bus was going through a part of town known to have a high illegitimacy rate? Would you refuse to yield your seat, on the likelihood that the it was the pregnant lady's fault, therefore, she should pay (suffer) for her misdeed?
Now, let's look at a harder one: a man boards, with a broken leg and crutches.
What about if you know that the man got his broken leg while showing off, doing a very dangerous stunt?
What if (in a very small town) you knew that one man broke his leg in a very dangerous stunt; and another man broke his leg rescuing children from a burning car. A man boards, with a broken leg, but you do not know which man it is. What then?
A man boards. He stands there, sweat dripping off him, his face white, obviously about to collapse. Give him your seat?
What if the above man had a very large abdomen? What if you knew that he had a swollen liver, heart, etc.? What if you weren't certain about this particular man?
Now, for the hardest one: a man gets on, who is obviously obese. "Everyone knows" that how people get fat is by eating too much, and not exercising enough, right? So, should this man have to "pay" for the bad behavior of eating too much?
What if (in the above scenario) you knew as an absolute fact, that there are many medical and genetic problems (not to mention medications), which result in intractable obesity? What if you knew that the obese man was a victim of one of these medical/genetic problems?
What if, in the above hypothetical, you knew that some portion of obese people are such, due to medical/genetic problems, but you don't know whether this particular man is one of those people, or if he just eats too much? Do you presume that he is a glutton, and therefore he must pay for his wrong behavior?
Just food for thought. Don't eat too much. ;--)
DG