Verbos de opinión: pensar, creer, opinar

Thought verbs — pensar, creer, considerar, suponer, opinar, dudar, saber — are the verbs you use to say what's in your head: opinions, beliefs, guesses, knowledge, doubts. They share a tight piece of Spanish grammar that has no English equivalent: the mood of the subordinate clause flips when the thought verb is negated. Creo que viene (indicative — I believe she's coming) becomes No creo que venga (subjunctive — I don't believe she's coming). This page maps the whole class and the logic behind that flip.

The basic structure

Every thought verb in this class takes one of two structures:

1. Thought verb + que + subordinate clause — for full thoughts ("I think that he's coming").
2. Thought verb + en / de / sobre + object — for "thinking about" something.

The first structure is where the mood question lives.

The mood flip: assertion vs non-assertion

Affirmative thought verbs assert that the speaker holds a belief — they project the subordinate content as a candidate fact. The subordinate verb goes in the indicative, because the speaker is treating the content as real.

When you negate the thought verb, you are no longer asserting the content — you are pushing it out of the realm of accepted reality. The subordinate verb then goes in the subjunctive, marking the content as non-asserted, doubted, or denied.

The question form: indicative or subjunctive?

Questions with thought verbs sit in the grey zone. The choice between indicative and subjunctive depends on what the speaker is doing:

• ¿Crees que viene? — Genuine question, no opinion implied. Indicative.
• ¿Crees que venga? — Doubtful question; the speaker leans toward no. Subjunctive.

In peninsular Spanish, the indicative in questions is by far the dominant choice. The subjunctive question (¿crees que venga?) is more common in Latin America and signals that the speaker doubts the proposition.

Saber: outside the flip

Saber (to know) behaves differently from the other thought verbs because it asserts fact, not opinion. Even when negated, saber doesn't typically trigger the subjunctive in the way creer and pensar do — it tends to introduce an indirect question instead.

• Sé que viene. — I know she's coming. (indicative — a known fact)
• No sé si viene. — I don't know whether she's coming. (indicative — embedded yes/no question)
• No sé qué quiere. — I don't know what she wants. (indicative — embedded wh-question)

You can hear No sé que venga in informal speech meaning roughly "I don't reckon she's coming," but the standard form for "I don't know whether" is no sé si. Treat no sé si + indicative as the safe template.

Dudar: doubt always triggers subjunctive

Dudar is the mirror image of creer. Where creer asserts, dudar denies — and the subordinate verb is always in the subjunctive in the affirmative.

• Dudo que venga. — I doubt she's coming. (subjunctive)
• No dudo que viene. — I don't doubt she's coming. (indicative — the doubt is denied, so the content is reasserted)

This is the negation rule running in reverse: dudar is inherently non-assertive, so it triggers subjunctive in the affirmative; negating it cancels the doubt and restores the indicative.

The same logic applies to negar (to deny), which works exactly like dudar: Niega que sea cierto = he denies it's true (subjunctive); No niega que es cierto = he doesn't deny it's true (indicative).

Pensar en vs pensar de vs pensar que

Pensar takes three different prepositions depending on what kind of thinking is going on.

• pensar en + thing — to think about something (have it on your mind, mull it over).
• pensar de + thing — to have an opinion of (almost always in questions: ¿qué piensas de X?).
• pensar que + clause — to think that, to be of the opinion that.
• pensar + infinitive — to plan / intend to.

These are not interchangeable.

The pensar de / pensar en distinction is one of those small details that marks a learner from a fluent speaker. Pensar en is mental attention; pensar de is opinion. No pienso en ti = I don't think about you. No pienso nada de ti = I have no opinion about you. Two very different statements.

Creer en vs creer (que)

Creer also has a preposition distinction.

• creer en + person / thing — to believe in (have faith in someone, something, an idea).
• creer (que) + clause — to believe that, to think.

The reflexive creerse + clause has a slightly stronger feel of "buying it" or "swallowing it." No me creo que sea verdad = I don't buy that it's true.

Opinar, considerar, suponer: the rest of the family

These three round out the affirmative-asserting thought verbs. They all follow the same mood pattern as creer and pensar: indicative in the affirmative, subjunctive when negated.

• opinar — to be of the opinion (a slightly formal register, common in writing and discussion).
• considerar — to consider, regard as (often with an adjective or noun complement).
• suponer — to suppose, assume.

Polite hedges: a mí me parece que, en mi opinión

The most natural way to share an opinion in conversational Spanish often isn't creo or pienso — it's a hedged frame that softens the assertion:

• A mí me parece que + indicative — It seems to me that... (the workhorse polite opinion frame)
• En mi opinión
  • clause — In my opinion... (slightly more formal)
• Yo diría que + indicative — I'd say that... (very common conversational hedge)
• Para mí
  • clause — For me / to my mind...

These frames also follow the mood-flip rule: No me parece que sea buena idea = it doesn't seem to me to be a good idea (subjunctive).

Common Mistakes

Key Takeaways

• Spanish thought verbs — creer, pensar, suponer, considerar, opinar, dudar, saber, parecer — introduce a subordinate clause with que.
• The core rule: affirmative thought verb → indicative; negated thought verb → subjunctive. The flip marks the shift from asserting a belief to denying or doubting one.
• Dudar and negar are mirror images: they're inherently non-assertive, so they take subjunctive in the affirmative and indicative when negated.
• Saber sits outside the flip. No sé si
  • indicative is the standard "I don't know whether" frame.
• Pensar has three preposition patterns: pensar en (have on the mind), pensar de (have an opinion of), pensar que (think that), pensar + inf (plan to).
• Creer has two: creer en (believe in, have faith in), creer que (think that).
• Polite opinion frames — a mí me parece que, yo diría que, para mí, en mi opinión — also follow the mood-flip rule.
• The mood flip is one of the cleanest places where Spanish grammaticalises assertion vs non-assertion — a distinction English handles only through context and intonation.