If you’re going to use GDP as a proxy for power, well, I regret to tell you that China was by far the largest economy in the world in 1840 when they got their ass kicked by the British, and again in 1860. They lost to Japan in 1894 despite having 5 times the GDP.
I used the term “productive capacity” to more closely hint that that it’s something more like “GDP per capita—subsistence income”. Obviously if you’re spending 90% of your economic and productive resources keeping your own population alive, or if your state doesn’t have the political will/infrastructure to tax that income, then that GDP can’t easily be reallocated towards wartime spending. In modern economies we have a lot more wiggleroom and so GDP itself more closely approximates “wartime production power”.
Of course it’s not the only thing. Governors can just fail to use the resources they have to protect their citizens. But spare change to buy guns, missiles, etc. is a resource.
I used the term “productive capacity” to more closely hint that that it’s something more like “GDP per capita—subsistence income”. Obviously if you’re spending 90% of your economic and productive resources keeping your own population alive, or if your state doesn’t have the political will/infrastructure to tax that income, then that GDP can’t easily be reallocated towards wartime spending. In modern economies we have a lot more wiggleroom and so GDP itself more closely approximates “wartime production power”.
Of course it’s not the only thing. Governors can just fail to use the resources they have to protect their citizens. But spare change to buy guns, missiles, etc. is a resource.