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Twisted Logic

Posted by plosmedicine on 31 Mar 2009 at 00:16 GMT

Author: Tim Lossen
Position: Software Developer
Institution: No affiliation was given
Submitted Date: November 20, 2007
Published Date: November 21, 2007
This comment was originally posted as a “Reader Response” on the publication date indicated above. All Reader Responses are now available as comments.

The authors state that "[...] the fact that aspirin cures headaches does not prove that headaches are due to low levels of aspirin in the brain." While this is certainly true, the comparison is logically flawed. Nobody claims that depression is due to low levels of SSRIs in the brain.

No competing interests declared.

RE: Twisted Logic

Kusername replied to plosmedicine on 13 Jun 2012 at 19:49 GMT

The above comment confuses two different branch's of philosophy. Philosophy's major branch 'logic' concerns relations among ideas---the abstract. Claimed knowledge of facts in the world of experience---the empirical---is the concern of philosophy's major branch 'epistemology'. The authors used the example of Aspirin and pain's causation to illustrate 'ex juvantibus' reasoning---a question of logic---via the argument form 'If addition of A reverses state B, then state B is caused by insufficiency of A'.

Indeed, none of note claimed that depression is due to low levels of SSRIs in the brain. Rather, the claim was that depression is due to low levels of serotonin in the brain. This is an empirical question, not a logical question. Whether the claim is made about SSRIs or about serotonin does not alter the argument form---the relations among A and B. The authors were merely illustrating the argument form, not claiming that serotonin is empirically the same as SSRIs and the same as Aspirin.

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