[mxkopy]

> A self-sufficient community would not have a GDP of 0 because they would still have transactions among themselves. Perfect self-sufficiency would actually generate a very high GDP number because of how diverse and specialized the community would have to be to take care of itself.

And all this is assuming that the community uses money. A self sufficient community would have 0 GDP iff no money was exchanged.

[paxys]

That doesn't matter. Value was still exchanged, and can be measured.

[mxkopy]

I'd agree. Pedantically, though, this wouldn't be GDP by definition.

I do think you can substitute "sum of numerical value" for GDP in most non-technical contexts and have them make sense.

In this case it could be that an economy doesn't trade 'rationally', so summing numerical values doesn't make sense. E.g. I'll trade you 1 chicken -> 2 shoes, someone else will trade 1 shoe -> 2 chickens.

I guess there would still be some numerical measure, but it'd be more of a matrix than a single number.