I think it is an edge case, Mitch, because in most circumstances the person you describe needs more responsibility.

"Should the person who works longer hours be paid better?"

@Mitch: There are other ways of judging people's efforts apart from the hours they worked. These could be the work they actually did. You can get that easily from project reports as well as from other people. Personally, I'm not in favor of judging someone's performance through the number of hours they put in.

"It is best evaluated at the impact that your work has on the firm and on the people involved"

@sotheco: That's an apt way to judge someone's performance in your company. Sometimes the work you do may not itself be useful but you may be having a lot of positive impact on other people from your presence in the company. That may be hard to identify but it is important.

I think I may be arguing about an edge case here. 

It's easy to imagine a worker who works a 20-hour workweek, but whose work is so brilliant he's made himself indispensable to the organization. Management can try to entice him or bully him to work longer hours, but he has the power to refuse. Because of his brilliance. 

However, for the vast majority of people, who are mere mortals, effectiveness has a direct correlation to effort. 

Although there are studies showing that overtime isn't particularly effective either. 

It's complicated, though, because if someone is achieving their goals in a short working week, they don't have the right goals.

Good point. 'Achievement' isn't shown by the number of hours you've clocked in at the office, nor does it show by the number of reports you've turned it. It is best evaluated at the impact that your work has on the firm and on the people involved. Once you identify the high achievers in the firm, make sure you reach out to them and keep them happy so that they'll stay and continue to help the firm grow.

What if someone works 15 hours a day but is just bad at his job, and gets only half of his requirements done (and that, badly)?

What if someone else works a 40-hour week, but gets all that his required of him done, and more, and does everything well?

Should the person who works longer hours be paid better?

"That doesn't seem right to me -- or practical. We need to reward the high performers more. Otherwise, they'll go elsewhere"

@Mitch: That's exactly what my point was. Performance should be defined in terms of what you achieve. It should be defined as the magnitude of effort you put in. A high performer than becomes someone who's putting in the desired effort that was expected of him rather than what he achieved.

"It is the same thing with the advancement of civilengineering.Today we are in a position to buold more stable and high quality structures due to lessons learnt from failures of the past. And some of these failures have been really catastrophic"

@Paul: That's a good analogy. I think failures are better managed in science in engineering than they are in the business sector. This is something that corporate organizations can learn from the engineering field.