No: Less Consumption Does Not Cause More Investment

At risk of stating the obvious, in this post I’d like to highlight a pernicious misunderstanding that I find to be widespread out there in the world.

This is not new thinking. You’ll find a more sophisticated historical account, stated very clearly though in somewhat different terms, in the first few pages of this PDF. Still, despite decades of debunking, this misconception remains ubiquitous. I’d like to explain it in the simplest and clearest terms I can.

Start here:

GDP = Consumption Spending + Investment Spending

Consumption Spending = Spending on goods that will be consumed within the period.

Investment Spending = Spending on goods that will endure beyond the period.

Looking back at a period, from an accounting perspective, it’s obvious that if there’s less consumption spending, there’s more investment spending. This must be true, because that’s how we tally things up, once they’ve happened. There are two types of spending; every dollar spent last year must be one or the other. If there’s less of one, there’s more of the other.

But people conclude: if there is less consumption spending, there will be more investment spending. (So we’ll increase our stock of real stuff, and we’ll all be richer!)

They’re confusing (and confuting) a backward-looking, historical, accounting statement with a forward-looking, causal, predictive statement. Because looking back, GDP is fixed. It has to be; it’s already happened! But in that very instant of thought, people abandon that fixed, historical perspective and think: if one component is smaller, the other will be larger.

This makes no sense at all. Think about it: If people spend more on consumption goods next year, that will cause more production — including production of long-lived goods to increase production capacity. Investment won’t go down because people spend more on consumption. GDP will go up. Next year’s GDP (obviously) isn’t fixed.

Likewise, people tend to think that less consumption spending means there will be a higher proportion of investment spending (so, relatively, more real-wealth production). Wrong again. The backward-looking Y = C + I accounting identity tells us exactly nothing about why people will make their spending decisions — what causes them to choose consumption vs. investment spending. They might choose to increase or decrease either or both, for myriad reasons. One doesn’t cause the other in some kind of simple arithmetic manner.

This seems very obvious. But if you hold this firmly in your head as you peruse people’s statements out there in the world, I think that you will find that many of them do not have it fixed very firmly in their heads.

Cross-posted at Asymptosis.