Should a PM have working knowledge of the subject matter of the project?

This topic has been brought up several times in this forum. My view: it is not necessary (and even not recommendable) to be a SME on the project topic to succeed in a PM role.

It helps to know a bit, what I often find it that even if I know the answer I keep quiet to see what others say, it's a useful tactic for determining how much knowledge people have, and also pleading ignorance is a great way to get people to give you a little time and do some information gathering. However, be aware that you will rarely, and should rarely, know more than the people working with you as SME's and if you do that's a problem in itself!!

However, ending a 12 month project with the same amount of knowledge of what you have been working on as at the start doesn't reflect well on you as an individual as it's hard ot see how you could have attended 12 months of project meetings without picking up at least the lingua franca of the subject, so if you dont pick up a working knowledge as you go that's probably not right, whether in 2 years or 3 years that technical experience is still relevant is really not the issue.

I've seen good and poor results on both sides of the discussion. One thing I know for sure is that the PM doesn't typically need to be the expert. In fact, I've seen it happen where the "PM as expert" model slowed down the project because everything had to go through them.

Personally, I would feel much more comfortable having at least, in your terms, a working knowledge of the project's domain. But that could be related to having control freak tendencies. :)

As the Project Management is a continuous knowledge practice I do firmly believe that PMs don't strictly need the knowledge of the project, though, as experience given by working on a small firm taught me, it can highly be considered and rewarding

I'm reminded of why I did not like reading Doc Savage novels when I was a teenager. It did not matter that his team had the world-best people in their fields, Doc Savage was always better than them.

That's not what a project manager should be or do. She should have people that are better than her in their domain. Her job is to faciltate the team's skills and their efforts to get the best out of the team.

Does it mean she should not have some knowledge? Absolutely not. A good project manager has a breadth of knowledge that allows her to function in various context and under numerous conditions.