Yeah, but “wealth” is kind of meaningless. “Wealth” is money that is mostly made up. Say there are ten people with ten identical baseball cards. Nobody wants the other’s card, and so the market price of the cards is virtually zero. These people have zero wealth. Say an eleventh person befriends these people, and suddenly wants a card to be cool like the others. Noone wanted to give this person their card, but eventually the new guy gave somebody $1000 to part with theirs. Now the market price of a baseball card is $1000, and the total wealth of these ten people is technically $10k. However, if suddenly another person decides they don’t want a card at all (and the guy who sold his card to the 11th doesn’t want one either), then that person will try to offload it for cheap. Maybe the new guy, being new, will want a second, and he’ll pay $5 for it. The total wealth of these people can now only be described as $50.
Ok, the above was very confusing and only tangentially related to the real world. However, stocks, houseprices, and whatnot can become worthless rather quickly. The “wealth” represented by them is not a real measure of value. The closest thing to come to that is a summation of all the future income those things may bring. True, their real-world price is loosely coupled with that concept of future income. However, this coupling is, as i said, loose.
Worse, even if you try to go by the more merited concept of “future income potential”, you get numbers which may be correct for a capitalist definition of value, but are meaningless from a philosophical or communist perspective. For example, land may have enormous income generating potential, bringing in money until the end of humanity. Yet this value might not be the right one to consider. The income is an artifact of the way we decide who gets to use the land. It doesn’t actually represent produced goods or delivered services or anything productive. Counting the income generating potential of land as divisible worth is like counting the income generating potential of traffic tickets. Fines aren’t wealth. They’re just machinery of incentives made by society. (Yet counting the food-growth potential of land might be something appropriate.)
It would be very difficult to actually construct a figure entirely appropriate for answering the spirit of the question.
Also, Cecil seems to get a tad confused by the difference between income and GDP. Personal income isn’t technically part of the GDP (income is money you get while GDP is money you spend), but its equivalent, consumer spending, is only the third of GDP that doesn’t include government and corporations. Thus, per capita GDP is the much more appropriate figure of interest for communist musings. (Although that GDP must first be corrected with “purchase-price-parity”, ie one must recognize that you can’t just rely on exchange rates to know what the money is actually able to buy in its home country.)
But anyway, one can generally conclude that if we all split the whatever, we’d have enough for each to eat well, have shelter, and enjoy many comforts. However, the amount of the whatever is determined by dynamics and isn’t something static. If everyone was forced to share everything, most might decide it’s not worth for them to do anything and suddenly everyone will have the same nothing. The question “how much would we have if we all shared” rather totally misses the point of what actually determines how much we have. And frankly, that determining thing isn’t anything too concrete and inescapable. We could all be first-world rich in ten years if the gears are turned the right way. And like i just said, we could equally all have nothing if we don’t understand how the gears work. (Not that I’m trying to imply that we do.)