"ne pas penser": Subjunctive, indicative, or else?

From what I've learned, the subjunctive is used only if the subjects of the main and side clauses are different (apart from some exceptions such as sentences connected by “bien que”). But what if I want to say, e.g., “I don't think I can do it”? - “Je ne pense pas que je puisse le faire” would violate the above rule, but “ne pas penser” usually calls for the subjunctive. Would I just use the indicative here, “Je ne pense pas que je peux le faire”? Or is there another alternative?

Thanks for you help!

Hi, JannisK. 

When the subjects in both clauses are the same (** in meaning), the rule is to drop que and use the infinitve (since repeating the subject is redundant), which avoids the need for the subjunctive. So,

Je ne pense pas que je puisse le faire.      becomes

Je ne pense pas pouvoir le faire.

and Je ne pense pas que je peux le faire. is not acceptable.

However, I've seen this question discussed before and there seems to be some variation in the way a native speaker might apply the rule to .. ne crois pas que … and .. ne pense pas que …  Apparently most would undoubtedly stick to the rule, while another may think that Je ne pense pas que je puisse le faire is also acceptable. Why one would choose to say the latter is not clear to me.

** When the subjects in both clauses are the same, but not in meaning, the rule does not apply.

il ne pense pas qu'il puisse le faire  does not change if the two instances of il  do not refer to the same person.

Robert

Bonjour!

I just thought I'd add to the convo, in case you find it useful.

@JannisK, RobertC106 is correct, when both subjects are the same, then we switch (or rather we should switch) to an infinitive. That is because there are essentially two doubts introduced in both clauses on the same subject, so the second of which becomes redundant. 

It is true that some people do not follow the rule and simply use the subjunctive as it would appear with two different subjects. As to why they do this, some people are obviously simply making a mistake, however I think for some people they miss the element of doubt that the subjunctif conveys. “Je ne pense pas” obviously introduces doubt, but it is not as strong as the subjunctive. 

I hope this helps,

   -   Mitchell