Subjunctive with Doubt and Denial

When the speaker expresses doubt, disbelief, denial, or uncertainty about something, the subjunctive is triggered. This is the "D" in the WEIRDO acronym. The reasoning is straightforward: if you doubt that something is true, you are not presenting it as a fact, so the indicative (the mood of facts) is inappropriate.

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The Core Principle

Certainty → Indicative	Doubt → Subjunctive
Creo que tiene razón.	No creo que tenga razón.
Es cierto que llueve.	No es cierto que llueva.
Sé que habla español.	Dudo que hable español.

Key rule: When the main clause expresses certainty or belief, use the indicative. When it expresses doubt, denial, or disbelief, use the subjunctive.

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Verbs and Expressions of Doubt

DUDAR QUE (to doubt that)

Dudar always triggers the subjunctive (when followed by que):

• Dudo que sea verdad. — I doubt it's true.
• Dudo que venga mañana. — I doubt he'll come tomorrow.
• Dudo que sepan la respuesta. — I doubt they know the answer.
• Dudamos que funcione. — We doubt it works.
• ¿Dudas que pueda hacerlo? — Do you doubt I can do it?

NO CREER QUE (to not believe that)

The negative of creer triggers the subjunctive:

• No creo que tenga razón. — I don't think he's right.
• No creo que sea posible. — I don't think it's possible.
• No creo que haya bastante tiempo. — I don't think there's enough time.
• No creen que estemos preparados. — They don't think we're ready.

NO PENSAR QUE (to not think that)

Same pattern as no creer que:

• No pienso que sea buena idea. — I don't think it's a good idea.
• No pensamos que vayan a ganar. — We don't think they're going to win.
• No piensa que merezca el premio. — He doesn't think she deserves the prize.

NEGAR QUE (to deny that)

• Niega que sea culpable. — He denies being guilty.
• Niego que haya dicho eso. — I deny having said that.
• Niegan que exista el problema. — They deny the problem exists.

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The Creer/No Creer Switch

This is one of the most important patterns in Spanish. The verb creer (to believe/think) switches between indicative and subjunctive depending on whether it is affirmative or negative:

Affirmative (certainty) → Indicative	Negative (doubt) → Subjunctive
Creo que es difícil.	No creo que sea difícil.
Creo que tiene razón.	No creo que tenga razón.
Creo que van a venir.	No creo que vayan a venir.
Creo que sabe la verdad.	No creo que sepa la verdad.

What about questions?

Questions with creer can go either way, depending on what the speaker expects:

• ¿Crees que es difícil? — Do you think it's difficult? (neutral question, leaning toward expecting "yes")
• ¿Crees que sea difícil? — Do you think it's difficult? (implying doubt, leaning toward "probably not")

Tip: In everyday speech, both are used in questions. The subjunctive version carries a subtle tone of skepticism.

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Expressions of Uncertainty

These impersonal expressions trigger the subjunctive because they express possibility rather than certainty:

Expression	Meaning	Example
Es posible que	It's possible that	Es posible que llueva.
Es probable que	It's probable that	Es probable que vengan tarde.
Puede que	It may be that	Puede que tenga razón.
Es imposible que	It's impossible that	Es imposible que sepa eso.
Es improbable que	It's improbable that	Es improbable que ganen.
No es seguro que	It's not certain that	No es seguro que vayamos.
Tal vez / Quizá(s)	Maybe / Perhaps	Tal vez venga mañana.

Note on tal vez / quizá(s): These words can take either indicative or subjunctive. The subjunctive emphasises more doubt; the indicative suggests the speaker thinks it is more likely. Quizás viene (he's probably coming) vs Quizás venga (he might come).

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Expressions of Certainty (Indicative!)