I would like to point out that my position on the subject has actually changed in the meantime. I don't know if I would actually be considered a proponent of LTV at this time, strictly speaking. However, I still subscribe to the three arguments I initially proposed, so I intend to continue the debate.

To reiterate:

The descriptive aspect of a theory addresses how well a theory fits reality as it is (the actual state of affairs). The normative aspect of a theory addresses how well a theory fits reality as it should be (the desired state of affairs).

STV (Subjective Theory of Value) is the position that value is subjective, i.e. dependent on the preferences of individuals. In this view, prices are the result of a more or less fluid conflation of preferences. STV has been the dominant theory of value in economics for almost a century and a half.

This is the theory of value which is the justification and basis for capitalism, because it makes usury (profits, interest rates, rent, etc) desirable and removes exploitation from the social equation. If people subjectively (from their own starting conditions) decide to pay interest rates so they can reap the benefits of a loan, STV says that their decision gives the interest rates validity.

LTV (Labor Theory of Value) is the position that value is entirely made of, and more or less exactly determined by, labor. Any given commodity embodies a certain amount of labor. Labor, in this view, is not a commodity itself but the standard of value by which all commodities are measured. The exact nature of the labor which a commodity embodies differs from variant to variant. Marx used the "socially necessary labor time," which was an average of production time within a given industry. Carson's theory implies that the most efficient production times are those which will tend to dominate within a market, and that thus only that efficient production is socially necessary.

Because LTV links value to labor, it is innately anti-capitalist, since it implies that usury is invalid (no labor=no value created), that workers should get their full product, and that labor is not a commodity. LTV also does not recognize natural resources as commodities, since they are not the product of labor, putting it in straight opposition to the enclosures of the commons and foreign exploitation of natural resources against local interests.

A crucial distinction which is absolutely needed to get anywhere in any value debate is the distinction between use value and exchange value.

Use value is our anticipation of the degree to which any given object can fulfill our needs. Not even Karl Marx denied the existence of use values. In fact, it is use values, the fact that we have needs to be fulfilled and that we cannot fulfill them all ourselves, which make exchange necessary in the first place. From the LTV perspective, the fact that someone buys a given commodity only proves that the labor it embodies was in fact socially necessary: an object which no one wants to buy is not a commodity, and therefore does not embody socially necessary labor. The main difference between both theories is that STV only recognizes the existence of use value, which is subjective, while LTV recognizes the existence of both use values and exchange values.

Exchange value is the concrete expression of the labor embodied in a commodity, either in terms of other commodities, in terms of labor-hours, in terms of money, or any other form one prefers. The exchange value is what leads to a price. In STV, there is no need for the concept of exchange value: the price is directly determined by the interplay of preferences in supply and demand.

Why I believe LTV is the valid theory of value:

1. Because all components of price are reducible to labor.

We can roughly subdivide price in three parts: raw materials/capital/tools (the means of production), wages, and surplus (profits, taxes). Wages are obviously reducible to labor, as they are a payment for labor. Surplus is taken from the full product of the worker, and is therefore also reducible to labor. The last category is that of the means of production, but these means of production were obviously produced by someone. The price of any given tool is reducible to the same tripartite division (means/wages/surplus), two-thirds of which is reducible to labor, and one-third being itself a price which is reducible to... and so on and so forth until the first man produced the first tool, an action which is entirely reducible to labor.

2. Because a freed market would inevitably align prices with costs of production.

This is the Carsonian model. Basically, Carson, along with other mutualist thinkers, posits that in a freed market (a market freed from State distortions, banking monopolies, and all the other regulations and subsidies which prop up the current corporatist system and its power relations) prices would tend towards production costs due to competitive pressure. He calls this an LTV/STV synthesis, although I personally don't agree about it being a synthesis: I think it is merely finding LTV through a different argument. In this view, it is power relations which prevent prices from being aligned on production costs.

3. A fully automated economy implies lack of prices.

Imagine a scenario in which the means of production are fully automated, self-repairing, and commodities are automatically transported to consumers. In this scenario, no labor at all is required to produce anything desired by anyone, and therefore no one makes a wage. This means that commodities should be shared, since no one can buy them. Price should therefore be set to zero. This is the flip-side of argument 1: I showed that prices can be reduced to labor, and here I show that absence of labor entails absence of prices.

From here on, I suggest that the debate be given subdivisions for each argument as was done before.

I agree with Francois that you should create three subdebates, one for each of his enumerated points. Perhaps they should be rephrased as questions:

1. Are all components of price are reducible to labor?

2. Would a freed market would inevitably align prices with costs of production?

3. Does a fully automated economy imply lack of prices?