Learn Portuguese (Portugal): Se vivêssemos numa utopia, havia mais harmonia. - If we lived in a utopia, there would be more harmony.

The word se (if) sets up a hypothetical or imaginary situation—we don't actually live in a utopia. In Portuguese, "if" clauses that express an unlikely or unreal condition always require the Imperfect Subjunctive.

Why does vivêssemos have a circumflex accent when other forms like vivesse don't?

In the Imperfect Subjunctive, the nós (we) and vós (you all) forms always take a written accent to keep the stress on the correct syllable. For regular -er and -ir verbs like viver, it's a circumflex (ê or î). For -ar verbs, it's an acute accent (á).

The English translation says "there would be", but havia is the Imperfect past tense. Why aren't we using the Conditional tense?

Strictly speaking, the Conditional tense (haveria) is the grammatically correct choice for the result of an "if" clause. However, in spoken and everyday European Portuguese, it is extremely common to swap out the Conditional for the Imperfect Indicative (havia) because it is shorter and easier to say. Both are perfectly acceptable here to mean "there would be".

Could I use tinha instead of havia to mean "there would be"?