what are the downsides of voluntary taxation (https://en.wikipedia.org/wiki/Voluntary_taxation)? what would happen to a polity that used it as the sole form of capital allocation?

Neither fish nor biscuit. I organise Ethereum Singapore and help at clrfund.  I dont think I have to be who I am on Twitter here and I love it

what if we had communities use quadratic funding to allocate their preferences for public goods they care about instead?

a voluntary tax but you choose where it goes

The only problem is externality pricing.

Building https://negationgame.com

this is the biggest downside i see. worth asking: would whatever “tragedies” that occurred in this system still be better than the alternatives we observe today with compulsory payments?

Helping build ezkl and zkml applications 

what would the lottery mechanism be, how would it work?

U need to associate it with a lottery mech

The downside is people get smart n realize they’re being scammed

Chasing Curiosity. Empathetic Accelerationist. Founding Fullstack Engineer @icebreaker. YC S16, KB7. 
icbk.me/tayyab.fc

wouldn’t that mean that non-participants are simply non-beneficiaries? eg, don’t want to self calculate? no problem: you won’t receive whatever benefit you otherwise would have had you participated

Too much complexity. As much as people bitch about the current process, one in which everything has to be self calculated is too much of a mental burden.

Reinventing illiquid assets.

Starting with venture @ www.withgrove.com 

in theory, yes. in practice, no. trying to imagine what the possible negative externalities might be with a system like this. (we're currently working on a white paper that lays the mathematical foundation for the on-chain experiment)

In theory forced tax action is voluntary - you elect for and against it. Perhaps representative democracy is a bug post blockchain. 

Would great to run an on-chain experiment like the one cited in the wiki.