What about running community, dividing labor, allocating resources, and other such things? We live on a finite world and we can't do everything we want to do, so how do we decide where resources are allocated?

Nature doesn't allocate resources. That would imply some sort of guiding sentience behind nature. Individual species compete for resources and those that are most successful at doing so survive.

What is a better way of making large scale decisions? How do you decide if maybe we should displace several thousand people from their ancestral homes to build a space elevator, for example? Or how do you decide if you are going to allocate untold human and material resources into a space program or into a concerted health program to reduce disease and cure us of death?

And once a decision has been made regarding these things, how do you then prevent those who disagree with the decision from interfering?

No, I just don't want to live in a world where force is so decentralized that at any moment I could run into it. It's really about would you rather risk a large concentration of force going wrong rarely or many smaller uses of force going wrong regularly.

If there is no centralized use of force then decentralized use of force will reign supreme. Whomever can garner the most support will be able to use that force to make others do as they please, and as forces collide you get war and violence. When you concentrate force you still risk that, but much less frequently. And because of the way we've structured our government it is much easier to remove those who would do us harm when you have a few people at the head instead of many lesser people bringing force to bare.

TCP/IP and the "free" market were created within a society that only exists because of the use of force.

Because that is the only way progress can be had, unless you actually think we as a single species can move 100% lockstep together towards common goals. There are some truly massive and intensive projects in our future that will require massive amounts of natural resources and energy, and no doubt people will oppose those projects just as they have opposed countless others. Maybe we will be lucky and nobody will want to resort of violence to oppose them, but given our track record that doesn't seem likely.

If we do not authorize the use of force what is to prevent untold violence to be brought upon "peaceful" people by those who are not.