Full Idea
The older metaphysics became dogmatism because, given the nature of finite determinations, it had to assume that of two opposed assertions (of the kind that those propositions were) one must be true and the other false.
Gist of Idea
Older metaphysics became dogmatic, by assuming opposed assertions must be true and false
Source
Georg W.F.Hegel (Logic (Encyclopedia I) [1817], §32)
Book Reference
Hegel,Georg W.F.: 'The Hegel Reader', ed/tr. Houlgate,Stephen [Blackwell 1998], p.147
A Reaction
While dialethism in logic looks very dubious to me, I have every sympathy with Hegel when it comes to the reasonings of ordinary language. There it is much harder to know whether you are addressing truly opposed assertions.