Nice try, but getting 10,000 people to dig holes (e.g. gigantic infrastructure projects) ends up costing much more than what it takes for "one guy" to "design a microchip"
You may choose to disagree. Just as modern economists disagree with the LTV.
Modern economists haven't refuted this, and in fact many parrot it, and anyone saying they have rejected the idea is misinformed. See for instance https://bnarchives.yorku.ca/308/2/20101200_cockshott_nitzan_...
The LTV absolutely accounts for demand (what capitalists call "value") and in fact requires it for its description of how capitalism operates. It's really just saying there are two forms of value: aggregate demand and aggregate production costs, with competition driving prices down to production costs. If you don't agree with that, I don't really know how else to help because it's kind of a universal truth in a mass production market economy.
Economy is not a natural or exact science. There is a mainstream. But this does not mean that there is no valid inquiries and theories outside mainstream.
You are the one defending the LTV, not me. If value = labor, but not when that would be silly, it's a bit like saying F = ma, but not when that would be silly. No serious scientist would accept this formulation. You would be laughed out the room.
After millions of deaths, environment devastation, and political repression, Marxism deserves to be laughed out of the room as well. I hope it will be, some day.
I never said anything about "use the theory, except when its silly". What was silly was the example because of the lack of understanding of the parent comment: LTV does not work like described by that comment. You can not even properly criticize something if you do not understand it.
The moralist excuse to forbid or negate certain knowledge is also silly. Depending on where you live (USA, Europe), you probably post these comments in a society built (and perhaps even mantained) by an even larger kill count, but I never will use this as a way to refuse or negate discussion or knowledge.
I've already presented several scenarios where a different amount of labor did not produce a different amount of value. Your response has just been that "socially necessary labor" is different than "labor." But this is nonsense since we don't have any authority to tell us what is "socially necessary" and what is not. Indeed, we have many examples of socialist governments deciding that it's not "socially necessary" for certain groups of people to eat at all -- the Holodomor in Ukraine, or der Hungerplan in Nazi Germany.
Your examples are exactly as expected by LTV. LTV agrees that they do not produce different exchange values. The problem is that you are just ignoring what the LTV says, ignoring the theory definitions and is coming with your own ideas of what you think it says. And when I try to give you what the theory says, you just say that it is nonsense, saying more things that confirm that you have no idea about what you are talking:
> But this is nonsense since we don't have any authority to tell us what is "socially necessary" and what is not.
You do not need the authority. The theory describes the functioning of free markets, and capitalism running without hindrances. But taking into account the material reality that you need nature + labor to socially produce things and that in one side you have production, at the other side you have consumption and these things need to be balanced.
Pro tip: LTV was the mainstream of economical theories during the era when Adam Smith, David Ricardo, Marx, and all other classical economists published their contributions. All them agreed with LTV. Do you really think that you can refute it using so silly examples? In fact, there are several criticisms and known paradoxes that applies to older forms of LTV, but your attacks are missing even these older and more naive forms. Which is expected: you cannot formulate proper criticism for things that you do not fully understand and did not study.
That's not what Marxism says at all.