 Thomasius’ Application of the Doctrine of Reason contributes to the project initiated in the Introduction by outlining the means of avoiding error. Avoiding error involves the eradication of prejudices, which are among the causes of the corruption of reason and which are grouped into two main groups, namely, prejudices of authority and of precipitancy or hastiness. That, in turn, is accomplished through what he identifies as dogmatic doubt, not the Cartesian doubt that deems everything false so as to find a first indubitable principle, which is a pointless enterprise, according to Thomasius. Dogmatic doubt is the doubt about particular things, beliefs, and opinions, and this he found healthy and conducive to preventing error.