Robinson flipped it: investment comes first, savings follow.
Once you see how money & banking work, it’s hard to unsee.
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The Goodwin growth cycle shows it:
Investment drives output & jobs → higher employment boosts wages → rising wages can squeeze profits → investment slows → cycle repeats.
It starts with investment decisions, not household savings.
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So where does the money for investment come from?
Not from a “pool” of prior savings.
Modern banks create credit.
When they lend, they create deposits, new money instantly funding investment.
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Firms borrow → spend → raise output & incomes.
Only after incomes rise does saving appear in the data.
In national accounts, investment = saving — but causality runs from investment to saving, not the other way.
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If households save more by spending less, firms sell less.
Lower sales → lower profits → less investment.
Without another source of demand (govt deficits, exports), higher saving today can actually reduce investment.
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Keen’s extensions to Goodwin add private debt:
Firms invest if profitable demand is there.
If profits aren’t enough, they borrow, banks create the credit they need.
Mainstream macro blames crises on public debt or bad policy.
History tells a different story, The biggest crashes follow private debt booms , when households & firms load up on credit faster than incomes grow.
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1929, Japan’s 1990s bust, the 2008 GFC, all preceded by surging private debt-to-GDP.
In each case, public debt rose after the crisis, as governments absorbed the fallout.
Cause and effect are backwards in the textbook story.
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Private debt booms are dangerous because they fuel asset bubbles and fragile balance sheets.
When cashflows falter or rates rise, defaults spike and leverage turns into a chain reaction.
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In the 1960s, MIT's Jay Forrester created a simulation that changed how we think about supply chains: the Beer Game.
It revealed that even stable demand can cause wild production swings—now known as the bullwhip effect.
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The game has 4 roles: Retailer, Wholesaler, Distributor & Factory.
Each tries to meet demand & manage inventory—but only sees demand after it’s placed. That delay leads each player to guess, and missteps quickly multiply.
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If the retailer slightly overorders, the wholesaler overreacts, the distributor does the same, and the factory ramps up too much. That overcorrection leads to big swings—causing stockouts or bloated inventories.
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