Il periodo ipotetico
An 'if-sentence' has two halves: the se-clause (the condition) and the main clause (the result). Italian has three standard patterns depending on how realistic the condition is. Type 1 β reale: se + indicativo (presente / futuro) β presente / futuro / imperativo (likely or factual). Type 2 β possibile: se + congiuntivo imperfetto β condizionale presente (hypothetical). Type 3 β irreale: se + congiuntivo trapassato β condizionale passato (counterfactual past). The big new pieces here are the congiuntivo imperfetto and trapassato, both of which only show up after se and a few other triggers.
Type 1 β reale: se + indicativo β indicativo / futuro
When the se-condition is realistic or factual, both halves stay in the indicative. Se piove, resto a casa = if it rains, I stay home. Se hai tempo, vieni con noi = if you have time, come with us. Se studierai, passerai l'esame = if you (will) study, you'll pass the exam. The future after se is allowed in Italian (unlike English, which uses present after 'if'). This pattern is for things that ARE happening or LIKELY to happen β no doubt about feasibility.
Type 2 β possibile: se + congiuntivo imperfetto β condizionale presente
For hypotheticals β possible but not real right now. English: 'if I HAD time, I WOULD come.' Italian: se avessi tempo, verrei. The se-clause uses the congiuntivo imperfetto, the main clause uses the condizionale presente (lesson 21). Forming the imperfetto congiuntivo: take the imperfetto indicativo stem and swap to -assi/-essi/-issi endings. parlare β parlassi, parlassi, parlasse, parlassimo, parlaste, parlassero. avere β avessi, avessi, avesse, avessimo, aveste, avessero. Irregular essere: fossi, fossi, fosse, fossimo, foste, fossero. fare: facessi, facesse.... dare: dessi, desse.... stare: stessi, stesse....
Type 3 β irreale: se + congiuntivo trapassato β condizionale passato
For things that DIDN'T happen β pure regret or counterfactual past. English: 'if I HAD STUDIED, I WOULD HAVE PASSED.' Italian: se avessi studiato, avrei passato l'esame. se-clause: congiuntivo trapassato = avessi/fossi (imperfetto cong. of avere/essere) + past participle. Main clause: condizionale passato = avrei/sarei (condizionale of avere/essere) + past participle (full coverage in lesson 29). Se fossi venuto, avresti visto Marco = if you had come, you would have seen Marco. Italian distinguishes type 2 and type 3 cleanly; English often blurs them.
Mix-and-match patterns
The three types are templates, not rigid. Italians often MIX type 2 and type 3 when the condition is past but the result is present: se avessi studiato di piΓΉ, ora saprei la risposta = if I had studied more, I would know the answer NOW (cong. trapassato + condizionale presente). And in casual speech, you'll hear the indicative imperfetto in BOTH halves of a type-3 sentence: se lo sapevo, venivo = if I'd known, I'd have come. Grammatically loose, but extremely common spoken Italian.
Quick reference
Type 1 (real): Se ho tempo, vengo. = If I have time, I'm coming. Type 2 (possible): Se avessi tempo, verrei. = If I had time, I would come. Type 3 (impossible past): Se avessi avuto tempo, sarei venuto. = If I had had time, I would have come. The English translations preserve the distinction: 'have/come' β 'had/would come' β 'had had/would have come'.
