This is the 3077th most frequent Dutch word.
daartegen
"Daartegen" means "against that" or "on the other hand" in English.
In this sentence, 'daartegen' is used to refer to the idea mentioned earlier, indicating opposition.
Hij vond het idee goed, maar daartegen protesteerde zij.
He found the idea good, but she protested against it.
Here, 'daartegen' refers to the arguments, showing that no one opposed or argued against them.
De argumenten waren overtuigend, daartegen had niemand iets in te brengen.
The arguments were convincing; no one could counter them.
The use of 'daartegen' contrasts the enthusiasm expressed by the speaker with the reservation shown by the other person.