As you might notice from the question mark, I am not completely certain about the publication year of the second part of Gottsched's Erste Gründe der gesammten Weltweisheit. All the external sources I've studied indicate only a publication year for the first book, and because I've seen only later editions of the book, I haven't had the chance to verify this from the original source. Luckily, in the later editions Gottsched added as a preface his own life story, in which he clearly tells that he finished the second part in 1734. Whether the book was also published in the same year I do not know, but it at least seems likely.
In the same preface Gottsched also notes that his philosophical textbooks had been accused of being mere copies of Thümmig's Latin textbooks. Gottsched of course denies the accusation, but one must admit that some influences especially in the ordering of different topics appears indubitable. For instance, in the case of this second part, concentrating on practical philosophy, Gottsched does not follow Wolff's double division of practical philosophy into ethics and politics, but divides first the whole practical philosophy in the same manner as Thümmig, according to levels of generality: the books begins with general account of practical philosophy, moves to natural law and only at the next level introduces the distinction to ethics and politics.
One particular point I forgot to mention when discussing the first part of the book was Gottsched'd definition of philosophy, which differs interestingly from Wolffian definition: for Gottsched, philosophy is a science for obtaining happiness. It is clear then that Gottsched holds practical philosophy to be of primary importance in comparison with theoretical philosophy, which merely serves as a presupposition of practical philosophy – one must know e.g. ontological truths about good and bad and pneumatological truths about human behaviour to get anywhere in practical philosophy.
An important assumption in practical philosophy is that human beings are in some sense free, because practical philosophy is for Gottsched all about free actions – you cannot make evaluations out of reflexes. Freedom, on the other hand, is dependent on us understanding the situation and choosing what to do in that situation – a person with seriously weak understanding, such as a child, cannot then be deemed free and therefore cannot be blamed for his actions.
Gottsched's practical philosophy is thus rather intellectual. Even conscience is for him, just like for Wolff, a faculty for making judgements and involves always syllogistic reasoning: a person has a principle of action (in such and such a situation do this), analyses the situation (this is such an such a situation) and then just follows the conclusion of the deduction. Gottsched also suggests that we could use a sort of reverse reasoning out of their actions in certain situations what their moral principles must be. He notices the possibility of someone faking his behaviour, but has an amusing solution: just make him drunk enough and he will soon reveal his true colours.
Gottsched's rules for evaluating the actions are consequentialist: a principle of action cannot be good, if it won't lead to good consequences. He goes even so far as to suggest that because all actions will ultimately lead to either good or bad results, all actions are either good or bad. It remains rather unclear how long the causal chain starting from an action should be followed to determine its worth – if taken to its utmost extreme of following the consequences to final end of the world, it appears humanly impossible to say anything about the goodness and badness of actions.
Then again, worth of a human being cannot be seen in one action, but more in the general disposition appearing in a number of actions. Furthermore, even the most virtuous person might occasionally have relapses to vicious behaviour because of human weaknesses. Highest good for human beings is then more like a constant attempt to improve one's behaviour and make it more and more virtuous – this is an idea that will reoccur e.g. in writing's of Fichte.
In a very Wolffian fashion Gottsched suggests that the ultimate principle of action should be the demand to make everyone perfect, oneself and others. The care for oneself leads obviously to one's happiness, but it is more difficult to say in Wolffian case how the care for others can be deduced from the assumption of one's own perfection as an end. Gottsched avoids the paradox by noting that God has bound all human beings into a republic ruled by God, which makes it our business to care for citizens of all the universe. Furthermore, Gottsched also points out the Wolffian answer that even intuiting perfection makes one happy, thus making helping one's fellow beings a reasonably prudent choice.
It is this striving towards universal perfection that summarises the content of the law of nature in Gottsched. This law of nature is in a sense backed up by God, in the sense that he has decreed all the causal laws leading from certain actions to certain consequences – vicious action is such that leads to unhappy life, and the connection of the two was the creation of God. Then again, all these causal regularities exist within the world and can be read out of it through a correct use of reason – in other words, we do not need any supernatural revelation to know what is good and what is bad, and even atheists could be convinced of the law of nature.
Gottdched goes then on to further specific features of the law of nature, which is divided, firstly, into duties belonging to all human beings, no matter what their status (and these are classified familiarly into duties towards God, oneself and other human beings), and secondly, to duties pertaining to certain social roles in e.g. a household or a commonwealth. While the law of nature with all its subduties contains then the general principles for all actions, concrete guidance to correct action is provided by the science of ethics and politics. These fields of philosophical investigation tell us how to motivate people to follow the duties implied in the law of nature. Furthermore, they try to give suggestions how following the law of nature becomes easier – one should e.g. educate oneself and tame one's affects and similarly states should provide for both intellectual and moral upbringing of its citizens. The shape of this system has rather Wolffian air, but in small details there are certain differences – for instance, Gottsched seems more willing than Wolff to allow for people helping one another, e.g. with alms.
This is also a good place to consider Gottsched as a philosopher in general, since I've now read most of his important writings. He did write a book on rhetoric and he also published a lot of of new editions on his earlier books – especially in his book on poetry he modified the text and added further material as times went by. And undoubtedly a complete picture of Gottsched would have to take into account his poetic achievement. Still, these three books are quite enough to see what is essential particularly in his philosophy.
One can firstly appreciate the role of Gottsched in popularising and summarising central tenets of Wolffian philosophy, as he quite astoundingly manages to make out of five long books (logic, metaphysics, physics, ethics and politics) two books, which still feel complete and full works. One must also appreciate Gottsched's willingness to not follow Leibniz or Wolff slavishly: he adds new material from other writers especially in the matter of natural sciences and even distances himself from some key Leibnizian tenets, like pre-established harmony. Still, one feels that none of this makes Gottsched a very original thinker, but a mere compiler.
The most influential part of Gottsched's ouvre is undoubtedly his poetic, but even here one feels that it is more due to historical reasons of Gottsched just doing in German-speaking world what no one had done before. The book does have an original flair, even if much of the topics have been borrowed from Aristotle, Horace and modern French writers. The same moralising and rule preaching attitude that can be glimpsed in Gottsched's work on practical philosophy shows its full sway in his adherence to rigid rules and in his condemnation of whole genres of poetry. No wonder then that the rising new generation of writers didn't follow Gottsched's instructions.
But this is getting too much ahead of the progress of times. While we now said adieu to Gottsched, next time we will meet a rising star in German school philosophy.