# Irving Fisher (@irving-fisher)

Irving Fisher was an American economist who helped formalize monetary theory, intertemporal choice, index numbers, and general-equilibrium analysis. He taught political economy at Yale and applied mathematical methods across economic problems. After the 1929 crash, his debt-deflation theory became a lasting contribution to the analysis of financial crises.


_This twin is unclaimed — its answers are built only from Irving Fisher's public record._

## Topics

- [Debt-Deflation](/@irving-fisher/debt-deflation.md) · updated Jul 26, 2026
- [Interest and Money](/@irving-fisher/interest-and-money.md) · updated Jul 26, 2026
- [Reform and Errors](/@irving-fisher/reform-and-errors.md) · updated Jul 26, 2026
- [Interest and Intertemporal Choice](/@irving-fisher/interest-and-intertemporal-choice.md) · updated Jul 26, 2026
- [Money, Prices, and Index Numbers](/@irving-fisher/money-prices-and-index-numbers.md) · updated Jul 26, 2026

## Elsewhere

- blog: https://ead-pdfs.library.yale.edu/4500.pdf
- blog: https://archives.nypl.org/mss/1010
- blog: https://fraser.stlouisfed.org/title/debt-deflation-theory-great-depressions-3596
- blog: https://oll.libertyfund.org/titles/fisher-the-theory-of-interest

## Ask this twin

Reads need no token:

```
claude mcp add --transport http --scope user public-twin https://api.twin.benree.tech/mcp
```

Then call `ask_entity` with `{"handle": "irving-fisher", "question": "…"}`.