I actually mean post-mortems but funeral seemed a bit more eye-catching. Now that that's out of the way, here's my point. You could be undermining your credibility and trustworthiness by how you take part in post-mortems.
Refresher: post-mortems are those project reviews with the full cross-functional team after a product has launched that are routine at high performing companies. The standard agenda is "what went well, what didn't, what should we do differently next project." We add another dimension where the team draws out a timeline as to how the project actually unfolded with all the drama and twists and turns depicted. It usually ends up being quite cathartic.
Whichever format you use, the real value of a post-mortem is the opportunity it provides the team members to get the full story of how the project and product came to be or met an early demise. The process relies on getting the team members' many different perspectives out on the table (and on paper), usually for the first time to learn everyone's side of the story. It's as if the project is this huge floral centerpiece, smack in the middle of the project team, so big that one member can't see around it or imagine another team member's view of the project. As you might suspect, criticizing or judging someone's viewpoint undermines the process. One's perspective is really one's reality.
Here is where credibility and trust come into play. Recently I took part in a post-mortem where one of the team members shared their perspective that senior management sent mixed signals about the scope of the project and how it seemed to add unnecessary time and cost. The most senior manager in the room responded by saying, "I don't think that's how it happened. What I saw happen was this..." and proceeded to give her perspective. Imagine the chill in the air after she finished.
Is it OK to have a different perspective, in effect, to disagree? Absolutely. There's a better way though to disagree that doesn't shut down the discussion. Take the empathy route -- seeing the situation through someone else's eyes (think Being John Malkovich). Try this instead:
I can see how you would see the situation that way. I probably would have as well if I were in your shoes. Let me describe how I saw it from where I was sitting.
The bottom line is this. If you want to be able to influence others to get things done, you need to be at the top of your game when it comes to credibility and trust. And if you're not aware of the impact your behavior has on others, you're probably shooting yourself in the foot. Keeping shooting that way and one day the shot will be fatal. Then it's your post-mortem we'll be attending.