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About this book

What is a number, and what does it mean to understand one?

In The Foundations of Arithmetic, Gottlob Frege turns to the concept of number itself. This logical and mathematical investigation puts a familiar idea at the centre of a philosophical inquiry. The focus is not simply arithmetic, but the foundations on which our understanding of number rests.

Frege's subject brings philosophy and mathematics together. What do we mean when we speak of numbers? What does a foundation for arithmetic need to explain? These questions offer a reason to pause over something familiar and consider it with fresh attention.

What you’ll discover

  • The concept of number Look beyond familiar calculations to the idea at the heart of Frege's investigation.
  • Arithmetic as a question Consider arithmetic not just as something to use, but as something to understand.
  • Logic meets mathematics Explore a subject where logical inquiry and mathematical thought share the same central concern.
  • A philosophical starting point Let the question of number draw you into Frege's philosophy of mathematics.
  • Foundations worth examining Spend time with the basic ideas that give this investigation its purpose.

Who will love it

This book will delight readers who love sharp arguments, the roots of modern logic and the philosophy of mathematics, and anyone who has wondered what numbers really are.

What’s inside

The key ideas, in the 15-minute summary

  1. One needs a definite meaning
  2. Justification matters more than mental images
  3. Arithmetic needs proofs rather than pictures
  4. Number depends on what we count
  5. Collections of units hide a problem
  6. Statements of number concern concepts
  7. Matching establishes the same number
  8. Logic supports the construction of numbers
  9. Keep meaning and justification in view

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Philosophy & Ideas

The Foundations of Arithmetic

by Gottlob Frege · 1884

Frege probes the nature of numbers and finds no adequate answer in Mill, Kant or many others.

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In short

What is the number one? Most people answer that it is a thing.

The Foundations of Arithmetic by Gottlob Frege, the cover

The Foundations of Arithmetic at a glance

Reading time
About 2 h 35 min2 h 5 min fast, 3 h 5 min slow
Length
37,200 words
Library level
Challenging long sentences, a rich vocabulary
First published
1884by Gottlob Frege

Reading time at 238 words a minute (fast 300, slow 200). How long the classics take to read · Updated

From the 15-minute summary · Key idea 1

Even the number one lacks a clear definition

Frege begins with a simple test. Ask someone what the number one is, and they will likely say it is a thing. But that is no definition. It says only that one belongs among things, not which thing it is.

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15-minute summary
The key ideas of the whole book in about 13 minutes. A good first look, or a refresher.
Details
First published
1884
Language
English
Level
Challenging

Cite this edition

Frege, Gottlob. The Foundations of Arithmetic. Library of Alexandria, 2026, libraryofalexandria.com/products/the-foundations-of-arithmetic.

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What is The Foundations of Arithmetic about?

It asks what a number is and what the truths of arithmetic rest on. Frege reviews rival answers, shows where they fail, and defines number through concepts and one-to-one matching, arguing that arithmetic grows out of logic.

What does Frege mean when he says number belongs to a concept?

He means that a count tells us something about a concept, not about a heap. The same cards can be one pack or fifty-two cards, because each description uses a different concept, and the concept carries the number.

Is arithmetic analytic or synthetic according to Frege?

Frege argues that arithmetical truths are analytic and a priori, since they can be proved from logical laws and definitions. He contrasts this with Kant, who held them to be synthetic, and with Mill, who held them empirical.

The author

Gottlob Frege

1848–1925 · German philosopher and logician

German philosopher, logician, and mathematician.

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