I will concede that economic calculation can take place under collectivist and communist arrangements. However, I believe that money and a taxation/redistribution scheme is the best bet for the near future.
Otto Leichter and others argued that labor-time could be used as a unit of accounting for calculating and planning an economy. The weakness of this approach is that different kinds of labor are not necessarily equivalent. However, you could create a system of labor-time accounting that specifies so much time of such-and-such a type of labor. This would solve that problem. Furthermore, two workers doing the same work may not work at the same pace. Under ordinary money systems, the more efficient worker may receive higher wages than his less productive co-worker. Of course, management could just measure the productivity of each laborer, then move the least productive workers to a different task where they might be more efficiently used. Measuring productivity by tracking how much work each laborer does would rectify this. Such labor-time approaches to calculation are somewhat feasible. Furthermore, this approach actually arose from trial and error in real-world socialist economies. In the utopian communities of Robert Owen and Josiah Warren, they put these systems to the test. For the most part, these experiments served as a proof of concept, but they were not necessarily efficient. And labor-time accounting works best when labor-notes are allowed to function almost exactly like money, so it seems a bit unnecessary to even take this route.
This labor-time accounting approach may be worse than full communism, perhaps worse than existing arrangements. Otto Neurath and Amadeo Bordiga did a decent job of defending the full communist approach. By tracking productivity and the quantities and quality of resources, it would be possible to have “calculation in kind” in a moneyless economy without exchange.
However, prices reflect demand among consumers and indicate to planners what they ought to be producing. The abolition of money and free exchange means that supply and demand can't easily guide the allocation of resources. It is conceivable that science could be used to determine what people need. A thorough study of nutrition and health could help to determine how much of various necessities ought to be produced and how they ought to be distributed.
However, the bulk of items are luxury items. Just how many fidget spinners ought to be produced? Or should resources currently wasted on producing fidget spinners and glow sticks be redirected towards producing computers? Determining demand (desires of consumers) in society will be much harder without the pricing mechanism. Either the planners can make this determination in a top-down fashion, creating a nanny state in which economic planners decide what is best for everyone else, or the planners could let consumers decide what ought to be produced. Perhaps they will let consumers vote on how much they value each item that could conceivably be manufactured. This seems to me to be a very bad approach either way. The first option creates an oligarchy of central planners while the second is probably not really feasible. People simply don't have the capacity to vote on all possible options. Entire lifetimes would be wasted voting on which products to produce without much time to enjoy the consumption of them. Pieter Lawrence had argued that people's desires can be communicated via requests for goods or services, so that organizing production in order to satisfy the needs and wants of the community really only requires communication.
I personally reject both calculation in labor-time and calculation in kind. These two approaches to calculating how resources ought to be allocated seem to me to be problematic. I will concede that these are theoretically possible solutions. Nevertheless, I think there is a better solution, which is less communistic but still very socialistic.
Fred M. Taylor, Oskar Lange, and Abba Lerner had a much simpler and more feasible approach. The pricing mechanism creates a sort of “democracy of the marketplace.” Each dollar is basically a vote. Demand, then, reflects the desires of people as expressed through a democratic market process. The problem is simply that people are not evenly represented in the marketplace. Some people have billions of dollars while others have none. This could be rectified by ensuring an egalitarian distribution of wealth. We could just keep the current system of money but eliminate poverty and excessive accumulation. Price, as a reflection of demand, would then accurately reflect the desires of the populace. The pricing mechanism would then be used to determine how resources ought to be allocated. If the price of an item drops, produce less of that item. If the price increases, manufacture more. Allocation of resources in a socialist economy could be based on supply and demand. There is nothing wrong with the pricing mechanism and supply-and-demand per se. The problem, rather, is with the unfair and unequal distribution of wealth and purchasing power.
The Lange-Lerner model of socialism proposes nationalizing land and natural resources as well as large-scale industry. The profits from nationalized industry and from ground-rent of nationalized land would then be distributed out to the entire populace in the form of a social dividend, giving all citizens a universal basic income. Then you could tax excessive accumulation on the other end, thereby eliminating the disparity of wealth distribution. I would propose implementing a progressive demurrage (tax on accumulation) in order to prevent excessive accumulation. A person ought to be allowed to save up for a big purchase but prohibited from hoarding too much wealth. I have explained this idea elsewhere:
A person who hoards money and does not spend it ought to be charged a demurrage fee, a tax on accumulation. This could be collected on the total amount of your savings at the end of every year or every several years. This tax should be progressive, so a person can still save up for retirement or for a big purchase but cannot amass a fortune. For instance, if you have less than 50,000 dollars, then you would pay a demurrage tax rate of 0%. If you were to accumulate 50,000 dollars, perhaps you would pay a 5% demurrage tax. Then the rate might be raised to 10% at 80,000, 20% at 120,000 dollars, 30% at 150,000 dollars, 40% at 180,000, and so on. This tax would penalize excessive accumulation.
This approach of minimizing inequality and simply using the pricing mechanism of the market to determine how resources ought to be allocated seems to me to be the best approach.
The labor-time approach seems to be no improvement over conventional monetary arrangements and really only makes sense if the goal of planners is to try to limit price to cost of production. However, that is a disastrous economic policy, which real-world socialist experiments have proven to be problematic. Communistic arrangements do not seem feasible in the immediate future, but also seem inevitable in the long run. When scarcity is virtually eliminated through technological advancement and AI is able to compile and analyze information far more efficiently than any human ever could, full communism will be more easily obtainable. I think a more conventional social democratic approach combined with basic income or a social dividend from nationalized industry will probably be needed to equalize distributions of wealth and help push forward a transhumanist agenda in the transitional period.