In Germany the Weimar Republic was weak from the start

Many people believe it was, yes. The main reason for this was because of the constitution; it stated that the members of the Reichstag could be elected by proportional representation. This meant that the number of seats each party had was directly proportional to thenumber of votes they recieved. So 50% of votes = 50% of seats, 1% of votes = 1% of seats. This was a big weakness because it gave smaller, extremist parties such as the Nazi's a lot more power.