grammaticality - Tense agreement in conditional statements: "I could do whatever I want" vs. "I could do whatever I wanted"

Consider the following sentences:

1. 
   
   
   
   • If I had my own place, I could do whatever I want.
   
   
   • If I had my own place, I could do whatever I wanted.
   
   
   
   


2. 
   
   
   
   • She said I could do whatever I want.
   
   
   • She said I could do whatever I wanted.
   
   
   
   

Which ones are correct and why? Is the answer different in a conditional, or does that not matter?

Answer

Any of these may be correct; which is correct will depend on what you mean.

Had in the conditional sentences and could in all the sentences are inherently ambiguous. They are ‘past’ in form, but the form is employed in the first instance to express some degree of uncertainty or contingency. Consequently it cannot be known without further context whether they are also being used to express tense—temporal location in the past. Let’s supply a context, to see the difference:

• I wish I had my own place. I want to throw a party next week. If I had my own place, I could do whatever I want—I could throw a party. I think I am going to get my own place and throw a party next week.
      OR
  ... If I had my own place I could do whatever I wanted ...

In this case, where all the action is located in the present, either is acceptable in any register. You would be more likely to employ the non-past form in formal discourse, to maintain strictly logical time reference; but in colloquial use you would be more likely use the past form, because all those past forms press for conformity.

In the following case, however, you must use the past form, because the “wanting” is located, with all the other action, in the past:

• I wished I had my own place. I wanted to throw a party the next week. If I had my own place, I could whatever I wanted—I could throw a party. So I got my own place and I threw a party the next week.

The same is true of your second example:

• I want to throw a party next week, so I talked to my landlady today. She said I could do whatever I want. So I’m going to throw a party.
      OR
  ... She said I could do whatever I wanted ...
      BUT


• I wanted to throw a party the next week, so I talked to my landlady. She said I could do whatever I wanted. So I threw the party.

It might be noted, however, that in the non-past example you would be even more likely to say “She said I can do whatever I want”, because that permission is non-past as well, and there's no contingency that interferes. You might even say “She says I can do whatever I want”.