Stating Opinions (The Indicative)
When stating an affirmative opinion in Portuguese, use the indicative mood. Verbs like achar que (to think that) express certainty from the speaker's perspective, so the following verb acts like a normal statement of fact.
| We think that the argument is false. | Achamos que o argumento é falso. |
Expressing Denial (The Subjunctive)
When you make the phrase negative, the certainty is removed. Expressing doubt or denial with phrases like não achar que (not to think that) triggers the subjunctive mood in the second clause.
Notice how the indicative verb é (is) changes to the subjunctive seja.
| I do not think that his argument is valid. | Não acho que o argumento dele seja válido. |
| I do not think that the error is obvious. | Não acho que o erro seja óbvio. |
Debating and Disagreeing
When discussing controversial topics, you will frequently use concordar (to agree) and discordar (to disagree). You can soften a disagreement by pairing it with não achar que, which forces the following verb into the subjunctive. Watch how ter (to have) becomes tenha and compreender (to understand) becomes compreenda.
| I agree with the professor, but I do not think that he has the solution. | Concordo com o professor, mas não acho que ele tenha a solução. |
| I disagree, and I do not think that the society understands the problem. | Discordo, e não acho que a sociedade compreenda o problema. |
Regular and Irregular Subjunctive Forms
Even opinion verbs like concordar take the subjunctive when following a phrase of denial. Observe how concordar becomes concordem (regular -AR verbs take -e endings in the present subjunctive), and the irregular verb querer (to want) becomes queira.
| I do not think that they agree with us. | Não acho que eles concordem connosco. |
| I do not think that the society wants another war. | Não acho que a sociedade queira outra guerra. |
