Gottlob Frege quotes

Every good mathematician is at least half a philosopher, and every good philosopher is at least half a mathematician.
 Gottlob Frege 
A scientist can hardly meet with anything more undesirable than to have the foundations give way just as the work is finished. I was put in this position by a letter from Mr. Bertrand Russell when the work was nearly through the press.
 Gottlob Frege 
The aim of scientific work is truth. While we internally recognise something as true, we judge, and while we utter judgements, we assert.
 Gottlob Frege 
'Facts, facts, facts,' cries the scientist if he wants to emphasize the necessity of a firm foundation for science. What is a fact? A fact is a thought that is true. But the scientist will surely not recognize something which depends on men's varying states of mind to be the firm foundation of science.
 Gottlob Frege 

...one can hardly deny that mankind has a common store of thoughts which is transmitted from one generation to another.
 Gottlob Frege 
It is possible, of course, to operate with figures mechanically, just as it is possible to speak like a parrot: but that hardly deserves the names of thought. It only becomes possible at all after the mathematical notation has, as a result of genuine thought, been so developed that it does the thinking for us, so to speak.
 Gottlob Frege 
The thought: A logical inquiry
 Gottlob Frege 
It really is worth the trouble to invent a new symbol if we can thus remove not a few logical difficulties and ensure the rigour of the proofs. But many mathematicians seem to have so little feeling for logical purity and accuracy that they will use a word to mean three or four different things, sooner than make the frightful decision to invent a new word.
 Gottlob Frege 

I compare arithmetic with a tree that unfolds upwards in a multitude of techniques and theorems while the root drives into the depths.
 Gottlob Frege 
Having visual impressions is, of course, necessary for seeing things, but it is not sufficient. What must be added is not anything sensible. And it is precisely this that unlocks the outer world for us; for without this nonsensible something, each of us would remain locked up in his inner world.
 Gottlob Frege 
There is more danger of numerical sequences continued indefinitely than of trees growing up to heaven. Each will some time reach its greatest height.
 Gottlob Frege 
Your discovery of the contradiction caused me the greatest surprise and, I would almost say, consternation, since it has shaken the basis on which I intended to build my arithmetic.
 Gottlob Frege 

What are numbers? What is the nature of arithmetical truth?
 Gottlob Frege 
Arithmetic has began to totter.
 Gottlob Frege
You may also like:

Alfred North Whitehead
Mathematician 
Alfred Tarski
Logician 
Bertrand Russell
Philosopher 
Charles Sanders Peirce
Philosopher 
Donald Davidson
Philosopher 
Edmund Husserl
Philosopher 
George Boole
Mathematician 
George Edward Moore
Philosopher 
Giuseppe Peano
Mathematician 
Gottfried Leibniz
Mathematician 
Hilary Putnam
Philosopher 
Immanuel Kant
Philosopher 
John Searle
Philosopher 
Kurt GÃ¶del
Logician 
Ludwig Wittgenstein
Philosopher 
Michael Dummett
Philosopher 
Rene Descartes
Philosopher 
Rudolf Carnap
Philosopher 
Saul Kripke
Philosopher 
Willard Van Orman Quine
Philosopher