[dredmorbius]

Strictly speaking, farming is where all our livelihoods come from, in the greatest part. We're all living off the surplus value of food production.

(Also of other food, energy, and materials sourcing: fishing, forestry, mining, etc.)

This was the insight of the French economist François Quesnay in his Tableau économique, foundation of the Physiocratic school of economics.

[eru]

You might find https://en.wikipedia.org/wiki/Margarine#Coal_butter fascinating.

> Strictly speaking, farming is where all our livelihoods come from, in the greatest part. We're all living off the surplus value of food production.

I don't think farming is special here, because food isn't special. You could make exactly the same argument for water (or even air) instead of food, and all of a sudden all our livelihoods would derive ultimately from the local municipal waterworks.

Whether that's a reductio ad absurdum of the original argument, or a valuable new perspective on the local waterworks is left as an exercise to the reader.

[dredmorbius]

Food (and other fuels) are special.

Water largely isn't fundamenally transformed with use (unless it's involved in a chemical reaction, though that's a minute fraction of all water usage), though it may be dispersed or degraded (usually contaminated with something). But it can recover its earlier state with appropriate applications of process and energy. Water (and much else we consume) is a material input rather than an energy input.

With energy inputs it is the energy potential itself which provides value, and that potential is intrinsically consumed in their use. Water, wood, iron, aluminium, lithium, helium, etc., can all be recycled, restored to their useful state, at comparatively little cost.

Collecting the waste products of food don't give you that, on two counts. First, most of the actual metabolic output is gaseous and lost to the atmosphere at large (CO2 and water vapour in your breath), and to the extent that solid and liquid human waste are useful in producing new food, it's a nutrient fertilisers which enable energy conversion of sunlight to fuel, and not the primary energy input itself (sunlight).

[eru]

I think you would want to be talking about entropy, not energy?

Recycling all the materials you mentioned costs 'energy' (to use your terminology). The same for food: we can use used-up food and a lot of energy and grow new food.

The process for 'recycling' wood is basically the same that for recycling food: you grow some plants. The waste products of used up wood are also basically the same as those for used up food.

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In any case, I don't see how any of this makes food more special than eg petrol or sunlight?

And you can argue that food is only useful, if we have air, ie oxygen to burn it with.

[bluGill]

Except in a few places drinkable water is in such abundance that nobody every spent significant effort trying to get it. Likewise for air, few people have ever spent much effort getting air to breathe - even in the worst polluted areas bottled air was reserved for airplanes, hospitals (and a few people with medical conditions), and scuba divers.

[eru]

And food is now in such abundance (at least in the western world) that we don't spend much effort on it, either. Or at least, if you only care about energy and nutrition, you can get it for really cheap. If you want something tastier, you can pay more. Exactly the same with drinks.

You could argue that water being so cheap is exactly what you'd expect when the surplus value of water production is sky-high: people only spend a fraction of their income on both food and water production, exactly because the surplus is so high.

Thus if water isn't the basis for all our livelihoods, neither is food production these days.