After showing his skill in metaphysics, Wolff moved on to publish a book called Vernünftige Gedancken von der Menschen Thun und Lassen. Considering that the new work was of the same length as the previous, I assume that Wolff must have worked with the two texts side by side.
The topic of the new book is Menschen Thun und Lassen, where Thun straightforwardly means doing something. The word Lassen is a bit more difficult to translate, but it is a counterpart of Thun and refers probably to someone being an object of an action. The issue of the book is then what human beings should do and what allow others to do to them – that is, it is a work of ethics we are dealing with.
Nowadays no book on ethics woud dare to ignore Hume's guillotine, but Wolff's work has grown in a more primeval climate, where no one had had the audacity to suppose that the is and the ought should be somehow separated. Thus, Wolff is not afraid to base ethics straightforwardly on metaphysics. Wolff had actually used normative notions like perfection already in his ontology. That is, according to Wolff, there are values which are independent of all actual inclinations of any subject, even God.
Characteristically Wolff adds that these values are not just embedded in the ontological structure of all there is, but they also determine the action of human beings – we all do what is good and avoid doing what is evil, provided we know clearly what is good and what is evil. The statement seems not so radical, if we remember that human beings are for Wolff always impure knowers, who must base everything on confused experiences.
Because true goodness lies in Wolff's opinion in perfection, he suggests as the primary principle of ethics ”make yourself and others more perfect”. One might wonder how Wolff makes the leap from the definition of goodness and the fact of human motivation to a commandment. Yet, Wolff has actually made such leaps even in mathematics – in postulates and problems Wolff has turned statements of the sort ”if A is done, B is the result” into rules of the sort ”if you want to make B happen, do A”.
True, Wolff's primary ethical principle appears to lack the condition inherent in the postulates and the problems. Yet, this condition is actually implicit in the fact of human motivation for good: because all people try to achieve goodness, they should perfect themselves and others. Wolffian ethical principle is then what Kant would later call a hypothetical imperative.
What appears more perplexing is why the perfection of other peoples should matter – surely desire for goodness would imply a motivation for only one's own perfection? But we must remember that for Wolff pleasure arises from mere inscpection of something perfect. Hence, the more the perfection for the world in general is acheived, the more joyful and merry will a rational person be.
This abstract enjoyment of perfection is the only inherent reward for good actions. But because God desires also good actions and the growth of perfection, He will reward the good people with further happiness (Glückseligkeit), Wolff states. Once again, Wolff does not naively think that good people would have all the luck (Glück) in the world – luck is something that varies very much from one context to another. Instead, he means by happiness a more permanent position – an unwavering state of serenity untouched by any external influences.
The story of Wolffian ethics will continue with a text on the capacity of grasping ethical truths.