When an external deficit and public deficit coincide, there must be a private sector deficit, which means that governments can only really run budget deficits safely to support a private sector surplus, when net exports are strong.
Answer: False
The answer is False.
This question relies on your understanding of the sectoral balances that are derived from the national accounts and must hold by defintion. The statement of sectoral balances doesn't tell us anything about how the economy might get into the situation depicted. Whatever behavioural forces were at play, the sectoral balances all have to sum to zero. Once you understand that, then deduction leads to the correct answer.
To refresh your memory the balances are derived as follows. The basic income-expenditure model in macroeconomics can be viewed in (at least) two ways: (a) from the perspective of the sources of spending; and (b) from the perspective of the uses of the income produced. Bringing these two perspectives (of the same thing) together generates the sectoral balances.
From the sources perspective we write:
GDP = C + I + G + (X - M)
which says that total national income (GDP) is the sum of total final consumption spending (C), total private investment (I), total government spending (G) and net exports (X - M).
From the uses perspective, national income (GDP) can be used for:
GDP = C + S + T
which says that GDP (income) ultimately comes back to households who consume (C), save (S) or pay taxes (T) with it once all the distributions are made.
Equating these two perspectives we get:
C + S + T = GDP = C + I + G + (X - M)
So after simplification (but obeying the equation) we get the sectoral balances view of the national accounts.
(I - S) + (G - T) + (X - M) = 0
That is the three balances have to sum to zero. The sectoral balances derived are:
These balances are usually expressed as a per cent of GDP but that doesn't alter the accounting rules that they sum to zero, it just means the balance to GDP ratios sum to zero.
A simplification is to add (I - S) + (X - M) and call it the non-government sector. Then you get the basic result that the government balance equals exactly $-for-$ (absolutely or as a per cent of GDP) the non-government balance (the sum of the private domestic and external balances).
This is also a basic rule derived from the national accounts and has to apply at all times.
To help us answer the specific question posed, we can identify three states all involving public and external deficits:
The following Table shows these three cases expressing the balances as percentages of GDP. You can see that it is only in Case A when the external deficit exceeds the public deficit that the private domestic sector is in deficit.
So the answer is false because the coexistence of a budget deficit (adding to aggregate demand) and an external deficit (draining aggregate demand) does have to lead to the private domestic sector being in deficit.
With the external balance set at a 2 per cent of GDP, as the budget moves into larger deficit, the private domestic balance approaches balance (Case B). Then once the budget deficit is large enough (3 per cent of GDP) to offset the demand-draining external deficit (2 per cent of GDP) the private domestic sector can save overall (Case C).
The budget deficits are underpinning spending and allowing income growth to be sufficient to generate savings greater than investment in the private domestic sector but have to be able to offset the demand-draining impacts of the external deficits to provide sufficient income growth for the private domestic sector to save.
The following blogs may be of further interest to you: