Even if free will is an artifact of our perception of a deterministic universe, I still find it extremely interesting that people who do believe in free will tend to be less constrained by their environments. For example, a child who experienced terrible abuse in a deterministic universe would have a very hard time having hope for their future. It becomes very easy to blame circumstances if you know that those circumstances are indeed necessarily the basis for your every choice.

If this example occurs in a universe with free will, there is no way to logically link previous circumstances with current choices. In a sense, giving the child control of their destiny.

Now in both examples, the Truth with a capital T could be that everything is deterministic, yet the behavior of the individual changes depending on how they view the universe, deterministically or with free will. If one believes that they have free will, they will function differently than if one believes that they have none. In this example I feel that the free will/determinism dichotomy is blurred, and really makes me question either side of the debate. It is almost as if belief can become a mechanism of some sort of strange ability to choose.

Ok ok, so our beliefs could be predetermined, but what about those who claim to believe in nothing? Or those who choose to believe in something just to believe in something (because believing in nothing makes it a bit hard to relate to others)?

Your example of the engineers makes me wary...

As an engineer, you are legally responsible for the answers you give, and ethically responsible for the lives you endanger by risky answers. So if you are forced to make assumptions about a problem, you make conservative ones! Even after conservative assumptions, if the appropriate data is not available, then factors of safety of 2 are common (meaning 50% of what you could have gotten away with if the assumptions were actually correct).

If this was a real life example, were there soil borings done to determine the soil types? Did the engineers even get to see the site, or were they given dimensions and just told to run the numbers? Engineers will only give you an answer they are comfortable standing behind if shit hits the fan.

You are right that an experienced excavator will be able to give a more accurate answer faster than an engineer, but there are always surprises. For example, there could be a lens of silt that undermines the structural integrity of the soil that no one would be aware of without a soil boring. As a civil engineer, I have seen contractors use there experience and just go at it. Sometimes it works fine...sometimes not so fine, and fingers start pointing. Contractors and engineers both have very important roles, and communication and respect needs to improve between the two in industry. It would be a bad idea to rely on an answer solely from an engineer or contractor.

Because it is a chance to work with other people and broaden the perspectives of wikipedians rather than just saying "fuck it", and doing your own thing.

Working with people who disagree with you is a pita, it's not something that most people are willing to do, and it can take a seemingly wasteful amount of time. Getting along with others is the real challenge, any yahoo can go make something and convince a few other yahoos that it's the best way.