This is absolutely clear from the following deduction.
- Good historians realize that inconsistency in belief is the norm for humans, and that any writer who has written enough will have achieved inconsistency.
- Good philosophers read anachronistically.
- People who do history of philosophy try to discern consistent interpretations that are not anachronistic.
- Therefore, the history of philosophy is neither good philosophy nor good history.
- Thus, from 4. by logic, it follows that there is no such thing as good history of philosophy. Q.E.D.
I think I'm actually serious about this.*
*This being said, the above deduction should make us appreciate all the more people like Frederick Beiser, Jonathan Bennett, Strawson, and Martha Nusbaum who manage to do good history and good philosophy, though the fact that Bennett, Strawson, and Nusbaum are routinely derided by other historians of philosophy for being anachronistic proves my point in the most chilling possible way. Beiser rocks so much that he is sui generis. If the phrase "the exception that proves the rule" means anything, then Beiser's picture is in the dictionary next to it.]