Expressing certainty and doubt in Spanish : complete course

What Does It Mean to Express Certainty and Doubt in Spanish?

When we speak, we do not always say things with 100% confidence. Sometimes we are sure about something. Other times, we are not so sure. Expressing certainty and doubt in Spanish means using specific words and structures to show how confident you are about what you say.

In Spanish, this is not just a matter of vocabulary. It also involves grammar, especially the use of the indicative and subjunctive moods. Do not worry if that sounds complex — we will take it step by step.

Simple Examples to Get Started

Look at these two sentences:

• Estoy seguro de que viene. — I am sure he is coming.
• No creo que venga. — I do not think he is coming.

Both sentences talk about the same situation, but the speaker’s level of confidence is very different. That difference changes the grammar too. This is what makes this topic so interesting and so useful.

The Key Elements of Expressing Certainty and Doubt in Spanish

There are several building blocks to understand this topic well. Let’s look at the most important ones.

1. Expressions of Certainty

When you are sure about something, you use expressions followed by the indicative mood. The indicative is the ‘normal’ form of the verb that you already know.

• Estoy seguro/a de que — I am sure that
• Es evidente que — It is obvious that
• Es cierto que — It is true that
• No hay duda de que — There is no doubt that

Examples in context:

• Es evidente que hablas bien el español. — It is obvious that you speak Spanish well.
• No hay duda de que este libro es útil. — There is no doubt that this book is useful.

2. Expressions of Doubt

When you are not sure, you often use the subjunctive mood. This is a key grammar point in Spanish.

• No creo que — I do not think that
• Es posible que — It is possible that
• Dudo que — I doubt that
• No estoy seguro/a de que — I am not sure that

Examples in context:

• Dudo que llegue a tiempo. — I doubt he will arrive on time.
• Es posible que llueva mañana. — It is possible that it will rain tomorrow.

3. A Useful Overview: Certainty vs. Doubt

Why Does This Matter? Expressing Nuance in Real Life

Being able to express certainty and doubt makes your Spanish sound much more natural. It helps you communicate like a real speaker, not just a textbook robot.

Imagine you are in a conversation and someone asks: ¿Crees que habrá tráfico? — Do you think there will be traffic? You need to give a nuanced answer. You could say:

• Sí, estoy seguro de que habrá tráfico. — Yes, I am sure there will be traffic.
• No sé, es posible que haya tráfico. — I do not know, it is possible there will be traffic.

This kind of language makes you sound more confident, more polite, and more human. It also helps you avoid misunderstandings in daily life, at work, or when travelling.

Comparison with French and English

If you speak French or English, here is a helpful comparison.

As you can see, Spanish and French behave in a very similar way. Both use the subjunctive after expressions of doubt. English does not change the verb form, which makes this a new concept for English speakers to learn.

A Complete Example

Here is a short dialogue that uses both certainty and doubt:

• Ana: ¿Crees que María viene a la fiesta? — Do you think María is coming to the party?
• Luis: Estoy seguro de que viene. Ella me lo dijo ayer. — I am sure she is coming. She told me yesterday.
• Ana: Pues yo dudo que tenga tiempo. Trabaja mucho últimamente. — Well, I doubt she has time. She has been working a lot lately.
• Luis: Es posible que llegue tarde, pero creo que viene. — It is possible she arrives late, but I think she is coming.

Notice how Luis uses the indicative (viene, creo que viene) because he is confident. Ana uses the subjunctive (tenga, llegue) because she is not so sure.

Key Points to Remember

• Use the indicative after expressions of certainty: Estoy seguro de que, Es cierto que, Es evidente que.
• Use the subjunctive after expressions of doubt: Dudo que, Es posible que, No creo que.
• The expression Creo que (I think that) usually takes the indicative because it suggests some level of belief.
• The negative form No creo que takes the subjunctive because it introduces doubt.
• French speakers will find this logic familiar. English speakers will need to pay extra attention to the verb form.

Sources

• Real Academia Española (RAE) — Nueva gramática de la lengua española, 2009.
• Gili Gaya, S. — Curso superior de sintaxis española, Biblograf, 1964.
• Instituto Cervantes — El subjuntivo, Centro Virtual Cervantes, available at: cervantes.es