Mathew Forstater is right.  
  
There certainly is a "Das J. S. Mill Problem".  
Mill is well-known as a supporter of liberalism in the traditional sense  
of the word in Europe and UK, at least in his ON LIBERTY, but in  
PRINCIPLES he was prepared to note that there are so many exceptions to  
the "laissez-failre" principle. This makes it extremely difficult to  
capture his true position in the policy-making matters.  
He is indeed a big figure in the transition period from  
economic liberalism to the welfare state.   
  
In this sense he was a Janus-faced economist. I say this of course  
without implicating that he was not a sincere personality.   
  
Cheers.  
  
Yukihiro Ikeda