Franz Brentano_The True and the Evident.pdf
Franz Brentano_The True and the Evident.pdf
Franz Brentano_The True and the Evident.pdf
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1<br />
ON THE GENERAL VALIDITY OF TRUTH<br />
AND THE BASIC MISTAKES IN A<br />
SO-CALLED “PHENOMENOLOGY”<br />
I<br />
<strong>Brentano</strong> to Husserl<br />
Florence, 9 January, 1905<br />
Dear Friend,<br />
I thank you for your cordial letter <strong>and</strong> good wishes which I warmly return. I have read<br />
with great interest what you say about your endeavours, over <strong>the</strong> long years that have<br />
separated us, <strong>and</strong> about your present point of view.<br />
If I underst<strong>and</strong> correctly, you distinguish a twofold logic. One is an art, 1 <strong>the</strong> o<strong>the</strong>r a<br />
<strong>the</strong>oretical discipline. <strong>The</strong> latter is supposed to comprise all pure ma<strong>the</strong>matics (geometry<br />
apparently being a discipline which is applied only to space). What is its subject-matter? 2<br />
Apparently objects of reason <strong>and</strong> <strong>the</strong>ir combinations. It is supposed to be a part of<br />
philosophy <strong>and</strong> not to be based upon our knowledge of psychology. And this latter seems<br />
to you to be <strong>the</strong> point of greatest importance, for o<strong>the</strong>rwise <strong>the</strong> validity of logic could be<br />
restricted to beings who happen to have <strong>the</strong> same make-up as we do. 3 This <strong>the</strong>oretical logic<br />
is concerned, not with evidence for us, but with an evidence of truths in <strong>the</strong>mselves, so to<br />
speak. You praise Bolzano as your teacher <strong>and</strong> guide.<br />
I must admit that I have several misgivings <strong>and</strong> I will not hesitate to mention <strong>the</strong>m.<br />
For even if you too should have second thoughts, you need not be discouraged. 4 For it<br />
does seem clear, generally speaking, that all or most of <strong>the</strong> questions which you take up in<br />
your so-called <strong>the</strong>oretical logic will find <strong>the</strong>ir proper place in o<strong>the</strong>r classifications of <strong>the</strong><br />
sciences. 5<br />
I think you may be justified in holding that <strong>the</strong> task of pure ma<strong>the</strong>matics falls within <strong>the</strong><br />
sphere of logic. But what seems unclear to me is whe<strong>the</strong>r this logic is anything o<strong>the</strong>r than<br />
<strong>the</strong> art of logic.<br />
We do speak of <strong>the</strong> “art of calculating”, after all. And in ma<strong>the</strong>matics do we not learn<br />
to perform certain logical operations, such as adding, subtracting, multiplying, dividing,<br />
extracting square roots, <strong>and</strong> so on?<br />
Was not <strong>the</strong> discovery of <strong>the</strong> differential calculus, in particular, <strong>the</strong> discovery of a<br />
ma<strong>the</strong>matical procedure, with <strong>the</strong> result that Leibniz’s symbolism, so superior to that of<br />
Newton, proved to be a great step forward? Even <strong>the</strong> invention of calculating machines<br />
could be mentioned.<br />
To be sure, not only do we learn how to add, but we also learn certain laws, certain<br />
equations stating what adds up to what, as “2+5=7”; not only do we learn to multiply,