A game is not fair if the rules are not the same for everyone. At least, I would like to believe that anyone who watches sports would agree with this statement. Moreover, a game played with unfair rules is by its nature an unethical game. That's my opinion on the matter.<p>If in society it were made clear that copying everyone else's designs and market research were okay and to be sought when possible, then there would be little wrong with an open-source project copying the designs of a proprietary project. On the other hand, if a proprietary project is not allowed, in practice, to copy the designs of its competitors due to fears of legal problems or public backlash, then it would be unethical for an open-source project to copy other projects' designs since that would give the open-source project an unfair advantage.<p>At the same time, there is still an element of exploitation if in practice the only ones investing significantly in market research and R&D are the proprietary firms. After all, any time someone is reaping the benefits of someone else's work without giving back equally in one form or another, there is a type of exploitation going on.<p>Now, we should avoid thinking in black-and-white. We should avoid saying x is ethical while y is unethical. In the real system that is society, there are many variables involved, and these variables are floating point. You would need to plug all the values into the formula of ethics to really see the relative balance of ethics followed by any given project or company at a given time.<p>I can tell you from my own experience with (embedded software/hardware) R&D that coming up with a fully functional, reliable product in terms of design and approach is a <i>very</i> costly operation. Simply measuring and cloning someone else's product is worlds easier than designing it in the first place. After all, the people doing the R&D are filtering out all the bad ideas for you -- and most ideas are bad ideas, often for reasons not clear from the start.<p>Like I said, however, one of the most important factors to consider is whether everyone is playing by the same rules. Doing things your competitors are not allowed to do without getting into trouble is cheating. And cheating is unethical -- despite the inner animal in us thinking there's nothing wrong with cheating as long as we're the one benefiting. Remember: The question is not whether you <i>can</i> do it, but whether it's <i>ethical</i>. These are not the same thing.