It is easy to represent the ‘income-expenditure model’ in a graph. Some people find this helpful as a visual aid to understanding; others, not so much. For those who find graphs confusing, this post can safely be ignored. In terms of economic meaning, it does not add much to what has already been explained. But for those who are comfortable with graphs, they can be a handy tool for illustrating or thinking through the logic of a model.
We have seen that the ‘income-expenditure model’ combines key macro identities (introduced in parts 7 and 15) with particular behavioral assumptions to provide a theory of income determination (considered in parts 16 and 18). The behavioral assumptions relate to causation. The causation envisaged in the income-expenditure model has implications for the sectoral balances, some of which are the focus of the present post.
At the macro level, equilibrium requires that total demand in product markets equals total supply. This could occur at high or low levels of output and employment. Equilibrium implies stable output, but it does not ensure full employment.
Now that we have introduced ‘government money‘ and ‘commercial bank money‘, we are in a position to understand in basic terms how fiscal policy (government spending and taxing) is conducted and its direct financial effects. At this stage, the treatment is still cursory. There are more details that can be added in at a later time.
We have seen that a national currency enters the economy when government spends, and that the recipients of the government spending can use the currency for various purposes, including to purchase goods and services. Government is therefore an original source of funds.
There is another original source of funds that gives people the ability to make purchases. This other source is private credit creation. Put simply, a household or firm can borrow from a bank or other financial institution and use the funds to spend.
We saw in part 2 that to establish a currency, government needs to do three things:
1. Define a unit of account (e.g. dollar).
2. Impose taxes that can only be paid in that unit of account.
3. Spend or lend the currency into existence.
The most basic purpose of taxation (introduced in step 2 of the sequence) is to create a demand for the currency. Provided taxes are effectively enforced, we in the non-government will have a need to obtain the currency, because it is the only means of paying taxes.
Money can be thought of as an IOU (“I owe you”). The issuer of an IOU can buy goods or services from anybody who is willing to accept the IOU as payment.