2 4 D O C . 2 9 A P R I L 1 9 1 9
29. From Hans Vaihinger
Halle, 15 Reinhardt St., 27 April 1919
Highly esteemed colleague Einstein,
I should have sent back your book, which you so generously gave me in Berlin
to take along on Friday the 4th of Oct., to you long
But grievious days came
upon me since that time: not only did I undergo 2 serious eye surgeries, which re-
grettably did not alleviate my troublesome eye condition after all, but I also expe-
rienced a very tragic death in my home, where our only, highly gifted daughter de-
parted from this life on December 31, after becoming engaged at
addition to that came the many terrible political disturbances. That is why it is only
today that I am managing to return your book, which is of all the more value to you,
of course, since you had added handwritten comments in it. It was especially your
comments, though, that attracted my attention so much and gave me plenty of food
for thought, and it was precisely they that prompted me to take up the book again
Naturally, I read what Study says about the “Philosophy of As If” with particular
interest. He does not do me justice, primarily by placing me among the pragmatists,
from whom I differ
The basic principle of pragmatism states: Whatever is useful is true. Usefulness
is the criterion for truth.
My idealistic positivism states, however: Even those concepts that are notorious-
ly false from the theoretical point of view can nonetheless be of practical use to
thought and to life. This practical usefulness is not, however, therefore a criterion
for their truth.
It is by this sharply defined distinction, which must necessarily be strictly ad-
hered to, that my school diverges fundamentally from pragmatism, from which it
is also historically completely independent.
But it is obviously very convenient to do away with the—for so many—incon-
venient “Philosophy of As If” by placing it in the big discipline of pragmatism,
which is so easy to disprove.
To the contrary, the “Phil. of As If,” if it is taken on its own as it should, is abso-
lutely not so easily refutable, just as Study also was absolutely not able to disprove
my considerations on the nature of mathematical concepts. The concepts of point,
line, and surface, but above all the concept of the infinitesimal, are contradictory
constructs. Although modern mathematicians have tried to rationalize these con-
cepts, and they purport to have succeeded in doing so too, the old contradictions are
concealed inside their apparently rational definitions.
You recall that I invited you in October to become a chief co-editor in your field
for the new Annalen der
You thought it necessary to decline this