However if you agree that:
- The state should be allowed to keep secrets
- The state can't always be trusted to choose what should be secret or not
- There is a need to hold the state to account, but somehow not make all secrets public by doing so
Then there needs to be some subset of citizenry who can gain access to those secrets without the blessing of the state.
In history this has been likely to occur when a person with access to the secrets feels strongly enough about something that they feel the secret should be made public. For good reasons or bad reasons (which not everyone will agree with either way).
A good journalist can fulfil that role IMHO. I realise that "good" there is another assumption...