“Are you familiar with Say’s Law? Can you see how it refutes your assertion?”
Say’s Law is “products are paid for with products”, no? So if Country B destroys Country A’s Industry X, Country A could still pay for Country B’s products by selling products from its Industries Y, Z, A, B, etc. Country B could also buy more of Countries C, D, E, F and G’s products, since Country B would now be the only country in the world with Industry X, allowing it to demand more products in exchange for the Products X it sells. Are you familiar with the principle that, when two entities (individuals, countries, firms) trade, the side that benefits most (in numerical terms) is the side with less demand for the other’s products? Of course, any voluntary exchange is beneficial to both parties, but the degree to which each benefits can vary. Imagine two people, Person A, who produces 10 apples per week, and Person B, who produces 10 oranges per week. Person A really wants an orange, whereas Person B doesn’t want an apple as much. So, they engage in trade, and because Person A wants an orange much more than person B wants an apple, they trade 3 apples for one orange, meaning Person A now has 7 apples, 1 orange per week, and person B has 9 oranges, 3 apples. From an ‘objective’ standpoint, numerical measurement, person B did much better from this trade than person A. Even though they both benefited, B benefited more (in a numerical sense, which is the sense used in GDP measurements, etc). When speaking of countries, this measure of which side ‘benefits’ more from the trade is called the Terms of Trade, the quantity of imports bought by a unit of exports; the relative price of a country’s exports to its imports. As far as I’m aware, America’s terms of trade have fallen steadily over the past few decades. Could not this be due to other countries developing their industries, creating more competition and so reducing demand for US goods, thereby reducing terms of trade?
Say Person A finds a cheaper place to trade his apples for oranges, with somebody who really wants apples (Person C). Person B still wants an apple, and the only person he can buy it from is Person A. But, Person A is now no longer willing to trade Person B three apples for one orange, since he could get oranges cheaper from person C, and instead will offer just one apple per orange. So now, for Person B to get 3 apples, he has to trade away three oranges. This means that if, as before, Person B is producing 10 oranges per week, and trading one to Person A in exchange for apples, then each week he has 9 oranges and 1 apple, compared to before, when he had 9 oranges and 3 apples. This change in terms of trade has effectively reduced person B’s standard of living by two apples per week. B still benefits from the trade, as if he didn’t value 9 oranges and 1 apple more than 10 oranges then he wouldn’t have made the trade. He just benefits less than he did before, when he could get 3 apples for one orange thanks to Person A not having any alternative suppliers of apples.
As to the war and malinvestments, wasn’t much of the war industry made up of factories that had been converted to the production of tanks, bombs, etc? So, I imagine it would not have been too difficult for entrepreneurs and factory owners to convert the factories back to their original uses. Also, savings rates during the war were something like 25-30%, and when this all was invested, the new investment might have been enough to hide the effects of any malinvestments (meaning it wasn’t as good as it could have been without the malinvestments, but still good enough that the ill effects of the malinvestments weren’t noticed).