Investment and Output 2
Here I've translated the macoreconomic rule 'SPENDING = INCOME = OUTPUT, WHICH DRIVES EMPLOYMENT' into a negative feedback loop by adding an explicit goal of Output and Employment. As shown in 'Investment and Output 1', all the income earned has to be spent to maintain output and employment. Any shorfall in spending can be made up by any of the three sectors that contribute to total output. However, when spending/investment by the private sector is too small to maintain the required level of overall spending and the exports do not contribute enough to compensate for this shortfall then only the government can save the day through Net Spending, i.e. spending more than it collects in tax revenue. Taxation at any rate, according to Modern Monetary Theory (MMT) does not serve the purpose of financing spending but can be used legitimately to slow down an overheating economy. I have not taken into account 'structural reforms', which are often subject to the 'Fallacy of Composition' and of dubious value, at least in a recessive climate, according to MMT.