How can I take ownership if I can't contribute my own ideas?
Ownership is not just about contributing ideas. Everyone has "ideas." Rather, complete ownership to my (engineering) mind involves the following:
- Understanding fully what the goal of the project is, what has been done before, why what has been done before won't work, and what makes this new project so challenging with respect to the state-of-the-art.
- Determining possible courses of action (ideas, as you say) to achieve the new, challenging goal.
- Using your expertise (or developing expertise, as the case may be) to come to a determination of the pros/cons of each potential solution (i.e., idea).
- For the most promising potential solutions, implement/code/build prototype, etc., obtain needed feedback of how well or poorly it works, try the next "idea," if need be. Rinse, repeat.
- Write up your results using compelling/convincing arguments, submit, give convincing talks at seminars, conferences, job talks, etc.
Perhaps you have not done much of the writing up phase (I don't know, you didn't mention it in your post). But, the writing phase can be fairly grueling: reviewers of your papers are not going to show the same compassion that your advisor shows you. The world of science is not going to give you the benefit of the doubt. You must make a very compelling case as to why what you did makes sense for the problem you are aiming to tackle, why the results you obtained matter, why your idea is better than some other idea, etc. That is, you need to show people that you know in and out why you are doing what you are doing. Your advisor casting doubts on your "ideas" is no different than what the world of science does daily to all of us. The main difference being: your advisor cares, the rest of the scientific world doesn't (at least, not initially).
It seems like if I wanted to contribute my own stuff it would be an uphill battle, and I would need to defend my ideas very well, and fight him every step of the way.
Exactly, see my points above. This project is, after all, your baby, not his. The life of a researcher is an uphill battle.
But it seems that every time I do something extra, that I do in addition to (not instead of) what he told me to do, he finds something wrong with my idea, and wants me to do exactly what he told me to do instead of letting me carry out my idea.
This statement right here shows (to me, anyway) that you are not taking complete ownership of your project. The notion of doing something "extra" has no place in total ownership. This is your project, there are no extra credit points to be doled out: everything you are doing for this project is for you to show the world how you kicked this project in the behind.
So frankly I do not see the point anymore.
Although I don't know your advisor, I would say that it sounds like your advisor is trying to help you do what any sane, decent PhD advisor would do: to help you along the way to becoming a great, independent researcher. My advice would be to think about the above points. After you get your PhD, the feedback you get about what you are doing in your research goes way down: be grateful for the feedback your advisor gives you about your ideas during this stage of your career.
I think if you take a more proactive approach to your work, and do your best, you can have a rewarding research career. Don't give up!