I have literally no idea who the current author, Johann Gottfried Walther, is supposed to be: the only person with that name from the 18th century I have managed to discover was a musician. Of course, it could be possible that an organist might want to dabble with philosophy in his spare time, but it still feels rather peculiar.
As far as I know, Walther published only two philosophical texts, first one in 1724, titled Eleatische Gräber, oder Gründliche Untersuchung der Leibnitsischen und Wolffischen Gründe der Welt-Weißheit, which was meant to, as the title indicates, criticize Wolffian philosophy. This work had the pleasure of awakening the interest of J. F. Müller, a minor Wolffian, who wrote a defense of Wolff against it. Finally, Walther answered Müller with Gedancken über die philosophische Bigotterie, wobey zugleich auf dasjenige, was der so genante J. F. Müller aus Würtemberg, oder vielmerh der Herr Hof-Rath Wolff in der herausgegebenen Schrift Wahres Mittel etc. etc. wider dessen Eleatische Gräber eingewandt, zureichend geantwortet wird, und wider dessen Systema neue und umstößige Zweiffel gemachet werden.
The reason why I chose to write about this rather obscure work is that it shows much better style and philosophical acumen than other critiques of Wolffian philosophy I have met thus far. The nominal topic of the essay is bigotry: Walther portrays Wolffians as philosophical zealots, mindlessly following their leader who has contaminated their head with mumbo-jumbo.
In a truly original manner Walther compares Wolff's philosophy with Daniel Defoe's Robinson Crusoe. A superficial reason for this comparison lies in the supposition that both works combine factual statements with pure fiction. Yet, Walther has a more substantial analogue in his mind. Walther thinks that Crusoe's deserted island where the castaway manages to live by his own is as convincing as the solitary state of a human soul supposedly cut away from any real connection with other souls. And just like the interaction of Crusoe and Friday is at first made impossible by a language barrier, so is the interaction of soul and body denied apparently by Wolff.
Walther did understand that Wolff later downplayed the idea of pre-established harmony, but this just made him more convinced that Wolff was a devious fraud wanting to deceive his followers. It is remarkable that Walther found only this single issue not to his tastes and would have admitted the whole of Wolffian philosophy otherwise. He was also singularly aware of the reason why Wolffians adopted the pre-established harmony, namely, because laws of mechanics appeared to deny change of motion coming out of thin air. Walther understood the reason, but couldn't care less: if the interaction between soul and body contradict with laws of mechanics, so much worse for the laws.
Furthermore, Walther was not just satisfied with showing his disgust, but also had a good argument against Wolffian position. It is a reasonable assumption that the incapacity of human soul to control its body lies in the essence of the soul: spiritual beings just cannot have causal interactions with material beings. Then again, Wolff's system relies on God as the creator of everything there is, including the material world. Yet, God is obviously spiritual being also and thus essentially incapable of doing anything for the material objects, let alone creating them.
Walther's argument appeared already in the Eleatische Gräber, and it was answered in turn by Müller. The answer relies clearly on Christian assumptions. Müller suggests that there is nothing essential in spiritual substances that would prevent them from controlling material substances. Then again, in this particular world human souls appear to have no effect on bodies, so this must be just an accidental thing: current world is just built in such a manner that souls cannot interfere with it.
Müller's answer feels unconvincing, if you don't buy in the idea of creation or don't believe in afterlife. Yet, it has its own difficulties, even if you do. Walther points out that Müller's suggestion would make human souls in their current condition unfree, because they would be prevented of doing something that they would naturally be capable of. Thus, God would have made human unfree, when he created the world – a rather peculiar result in a Christian setting.
Next time we shall see another critic of Wolffian philosophy.