Subjunctive with Pienso vs No Pienso

Question

I have been taught that "No pienso que pueda hacerlo" is correct, but that "Pienso que puede hacerlo is correct."

It seems to me that both of these expressions indicate a bit of uncertainty and should therefore be in the subjunctive, but that is apparently not the case.

Is this just one of those "you just have to memorize it" situations?

Or maybe one of those "use the one that conveys the amount of uncertainty you want to express" situations? - AnnRon, Jul 19, 2015

If you fill out your profile with your gender and level of proficiency in English and Spanish, people will take you more seriously and be better able to figure out the best way to help you. Also, they'll probably give your post a vote. - AnnRon, Jul 19, 2015

Here's that vote! I promised. Thanks for filling out your profile. - AnnRon, Jul 19, 2015

Welcome to SpanishDict. - rac1, Jul 19, 2015

Answer 1

When you say pienso que- you are asserting what you think, just as when you say creo que you are saying what you believe. Even with supongo que it is saying what you suppose to be true. It is not just about absolute truth but asserting what you think is true.

You have to get to something like es posible que to cast enough doubt to need the subjunctive. But here you are not stating that you think it, just that it is a possibility.

Very helpful! Thank you so much!! - 008de875, Jul 19, 2015

De nada. :) - bosquederoble, Jul 19, 2015

Answer 2

To add to what bosque already said:

"I think that I can go to the party" conveys some certainty that I can go.

"I don't think that I can go to the party" conveys uncertainty and doubt about being able to go.

This is also true with:

creo que + indicative; no creo que + subjunctive

estar seguro de que + indicative; no estar segur de que + subjunctive

Check these links out for a better explanation and a bunch of examples!

No creer que...

No estar seguro de que...

Why english speakers say "Yo pienso"?. Native Spanish speakers 99% of times, say "Yo creo".. - txustaboy, Jul 20, 2015

Thank you for this comment. ¡Creo es excelente! - 008de875, Jul 20, 2015