system
Given the following post, respond as if you're commenting on Reddit:
human
I'm in a really unfortunate situation and I don't know what to do. Help?

I've been in a PhD program since 2015, working and paying for it out of pocket. I'm a social scientist in Canada. The time and effort I've put into this program have strained my mental health and my relationships and I'm finally done. I've got a completed dissertation and even published an article based on one of the chapters (atypical for my program). My advisor says I'm ready to defend, I should just run it by a member of my supervisory committee first. That professor came back and basically said "this is fundamentally flawed. You don't have the background to do this work." I asked what I should do about it and he said "I don't know." He doesn't want me to start from scratch this far in and still be unlikely to pass at defense.

My supervisor is standing by me. He's been great, actually, very supportive and available. Our rules state that I can proceed to defense if he approves it, even over the heads of the supervisory committee members (who do not sit on the defense committee). He's put together a committee that is more in-line with his expertise than with the dissenting supervisory committee member's expertise and says he thinks it will pass (one way or another--he's not ruling out the possibility of failure).

Some additional details:

\-My previous supervisor was denied tenure and basically fired from the department.

\-My new supervisor took over a few years ago and has been primarily driving the dissertation, but has limited expertise in my area.

\-The dissenting committee member is quite senior and certainly knows quite a lot about the topic I'm studying and thinks that it's fundamentally flawed and doesn't properly engage with the literature in that space.

\-I've been told that multiple people have failed defenses in my department in recent years. It's not unheard of at all.

\-Imposter syndrome is definitely a thing, but it feels like this validates mine. What have I been doing all this time? The dissenting supervisory committee member was polite about it; he acknowledged the work and effort that went into it.

I'm at a loss. If I had known this would happen I don't think I would have entered the program at all. I'm experiencing a crisis. I can't sleep. I feel sick all the time. It's had ramifications for my personal life. I have to make a decision about what to do really soon (within weeks).

Anyone have thoughts?

Thanks in advance.

Edit: I just want to thank everyone in the community for coming out. I've been reading your thoughts and they've given me a lot to think about. I wish I could share more information but I'm trying to preserve what little dignity I have left (heh!). It's looking like I will probably make some changes in consultation with my advisor and move forward with the defense this term. If I fail, I may be able to resubmit with revisions. If I pass, I will never set foot on the campus again. Either way I will update you all.
gpt
Can you go and sit with the senior “dissenter” and ask (perhaps with your new advisor) what should and can realistically be changed to make this a defensible thesis? Surely they are aware of your situation and need to work with you in a positive and fair manner. Stacking the committee is one approach, but another one is to try to move it forward.