quindi / dunque / perciò

In Italian, expressing consequence requires choosing the right connector based on the context and desired emphasis:

• Quindi: The most versatile choice. Unlike dunque and perciò, quindi can also indicate a chronological sequence (meaning 'then' or 'afterwards'). It is used in almost every situation, from casual speech to formal writing.
• Allora: A common informal synonym for quindi when expressing a logical consequence ('so').
• Dunque: Often used to summarize a logical argument or to resume a conversation. It sounds slightly more 'cultivated' than quindi. It can also be used as a filler at the start of a sentence (e.g., 'Dunque, vediamo...' - 'Well then, let's see...').
• Perciò: Literally 'for this [reason]'. It places a stronger emphasis on the motivation or the 'why' behind the result, belonging to the same everyday register as quindi.
• Pertanto: A strictly formal alternative to perciò and quindi, typically used in professional or academic writing.
• Sicché: Another synonym for quindi or cosicché, often used in spoken Italian (especially in Tuscany) or in literature to mean 'so that' or 'therefore'.

Idiomatic Usage:
In spoken Italian, the standalone questions E allora?! and E quindi?! are frequently used with a defiant or dismissive tone to mean 'So what?!' or 'What's your point?'. E quindi? can also be used neutrally to prompt someone to finish their story, meaning 'And then what happened?'.

Temporal vs. Logical Usage:
It is important to note that while all these connectors can show a logical result, only quindi can also be used to describe a sequence of events in time (e.g., 'Lavate le verdure, quindi tagliatele' - 'Wash the vegetables, then cut them'). However, for everyday chronological sequences, the standard word is poi ('then', 'next'), whereas quindi sounds slightly more formal or instructional. Additionally, while quindi means 'then' (next in a sequence), allora can mean 'then' in the sense of 'at that time' or 'back then' (e.g., 'Allora non c'erano i cellulari' - 'Back then there were no cell phones'). In these cases, dunque and perciò cannot be used.

Syntax and Punctuation:
These connectors usually appear at the start of the second clause, preceded by a comma, semicolon, or period. However, the position of quindi and dunque is flexible; they can sometimes follow the verb for emphasis (e.g., Non posso, dunque, venire). Crucially, quindi and dunque can also float between an auxiliary verb and a past participle (e.g., Pioveva, sono quindi rimasto a casa.). This is a major difference from English, where 'so' cannot be placed in the middle of a verb phrase (you cannot say 'I have so stayed home'). In contrast, perciò is rigid and almost always sits at the beginning of the conclusive clause. They are also frequently paired with 'e' (e quindi, e perciò), in which case the comma is usually dropped.