Advisor pushing for dead end topics I am new to this forum. I am encountering a problem in my doctoral studies that I haven't been able to find in an existing thread so I wanted to ask here. Any advice on how to navigate this would be very welcome.

I'm 2.5 years into my doctoral studies (geography) working under two co-advisors. Their areas of expertise broadly overlap with my dissertation topic, but the topic is my own, and I know the study area better than both of them. One advisor has been pressing for me to conduct a certain methods for social data collection that I knew wouldn't work (research fatigue is high in this area, distrust towards scientists without existing connections in these communities is a huge - if not insurmountable - obstacle). I tried to explain that these issues would make this type of social data collection very hard to pull off. I suppose I failed at this communication, because he pressed for this method all the same (with the rebuttal "science is hard"). Because he's an advisor I assumed he knew something I didn't, and I wrote up a dissertation proposal with this approach being used to answer one of my research questions (in my program a "dissertation" consists of three publication-ready papers). I emailed a few groups engaged in work in these communities. The reply I got was what I expected: they strongly advised against attempting to collect household surveys for the reasons I had tried to explain to my advisor before. I just got this reply today, I have not yet discussed it with my advisors. 

This does not sink my entire research proposal necessarily, but only a portion of it. There are other methods of data collection and analysis I'm still working on to answer the other research questions. Furthermore I spoke to my other co-advisor earlier in the fall (not a social scientist) asking what my recourse is if the social data collection component falls through for the reasons I feared. I was told not to worry necessarily, that we could figure out a way to work around it. 

That being said, I'm still worried. I'm worried that the advisor who pushed for the an approach that was ultimately dead-on-arrival doesn't fully understand my research. He's suggested approaches in the past that have turned out to be dead ends too. I'm also worried that I wasn't able to recognize this as a problem until I am 2.5 years into my program. The heavy initial course-load (full graduate course-load for the first two years) and first few research dead ends had me seeing the individual trees, not the forest. I'm sure a lot of this is my fault; I should have communicated better, I should have been more clear on what the expectations were. But now that I'm waking up to the fact that this is a problem, I'm not sure what to do about it. I have (excuse the lack of modesty) a good topic, and I think there's still a lot of value in seeing it through. I suppose I will have a better idea of what to do about this when we all meet next week, but an outsider perspective would be really valuable to me right now.

Thank you in advance
One piece of useful advice my thesis supervisors gave me was:


  We're going to throw a lot of ideas at you. You need to figure out which ones are worthwhile and which ones aren't.


If you know that something isn't going to work, then you need to figure out how to communicate to your advisor that it's not feasible. If you've tried and didn't succeed in making your case, try again using a different means of communication. Remember that the ability to make a convincing argument is crucial to success in research.