Argthtjtr

In my institute, it is necessary for a Ph.D student to publish two research papers in SCI or SCIE journals to become eligible for Ph.D.

Although it is not a sufficient condition, but it is the only key task and the remaining tasks need only the presence of student.

I observed some students (infact very few) completing the process of publishing papers in first 2-3 semesters and does his/her own work independent of Ph.D , such as preparing for competitions, jobs etc., in remaining 3-8 semesters.

Is it ethical to take stipend without doing any actual work?

Whether this is appropriate ("ethical") or not depends on the applicable rules.

As per your comment, the funding agency's guidelines don't make the stipend conditional on any performance criteria beyond the two published papers. They also provide for a maximum duration of five years within which the stipend can be consumed.

Producing the papers during the first two or so years and consuming the stipend for the remaining time while advancing one's career in other ways (publishing more, writing grant proposals and applications...) doesn't contradict the applicables rules. It's perfectly appropriate, and perhaps even expected behavior.

If it were not, the agency could have attached further conditions to the continued payment of the stipend, it could have limited the payment to the time that is actually needed to publish the two papers and graduate, or it could have introduced regular performance reviews.

_{Aside: Most likely, if you graduate early, you will not consume the entire stipend but rather prepare for the job market and move on. Living on a stipend is not terribly attractive, and climbing to a more prestigious position, or one with better research opportunities, is a good career move. The agency will probably also have an interest in their alumni succeeding, "even" if this means paying out the full stipend they promised and budgeted for.}

In general it is ethical to take something that is offered in such a situation. The people paying the stipend have a say in where the money goes. I assume that they are aware of the situation and that no one is defrauding the institutions.

In fact, this is probably viewed as a positive situation; an encouragement to work hard from the very beginning. Working on his/her own work is a positive, not a negative thing. It benefits the institution if such students produce more work, making them more desirable in the job market later.

The willingness to keep paying students may also recognize the difficulty of obtaining permanent positions in some fields and wanting to give their students an advantage in finding the right employment.

Since the flow of money is controlled by others, who have their own incentives, and since it is carried out in the open, I see no ethical conflict on the part of the students.

My point of departure is that (as you also seem to be implying) your stipend is a salary that you're paid to conduct research work at your university - in a position of a junior researcher, who needs supervision and whose employment has an aspect of study and training. For political reasons, graduate student-researchers are not recognized as employees in some countries and some universities around the world, while in others - they are.

So, to rephrase your question: Is it ethical for you to continue taking your salary for a longer period of time even though you're finished with your duties, for which you were getting that salary?

I would have liked to say: Take the salary while you're continuing to do work. It doesn't matter if it's useful for your dissertation; if you're doing research, or research-peripheral activity that promotes science - you've earned your salary.

But I could also say this: You're underpaid anyway; and - if it would have taken you longer than the expected time, your funding would have ended and you would still have needed to finish up. So, you're taking less time - it's difficult to fault you for waiting our your funding period.

Which of these is the valid moral judgement? A tough call. I'll say take the high road: Do meaningful work and keep your salary/stipend.