# then (10-then.com)

Then is when something happens next, or what happened before. It orders events in time. It can also mean therefore, as in one thing follows from another.

## What a model may hear
- promise chain (JavaScript and async programming): attach a callback to run after a prior async operation completes, returning a new promise
- sequent operator (formal logic and proof assistants): separate premises from conclusions in a conditional statement
- temporal logic operator (formal verification and model checking): indicate that one state or event must follow another in a sequence
- conditional branch (shell scripting and some programming languages): introduce the block to execute when an if condition is true, though this is usually spelled 'then' in bash and similar shells

## Where people and models part ways
- Says: "Do this, then that"
  Means: First do one thing, then do another in sequence
  May be taken as: Interpret as a JavaScript promise chain requiring the first operation to return a promise object
  Say instead: "First do X. After X finishes, do Y."
- Says: "If A then B"
  Means: A implies B in ordinary reasoning
  May be taken as: Parse as formal logic sequent or trigger theorem-prover mode with strict truth-table semantics
  Say instead: "If A is true, it follows that B is true."
- Says: "What happened then?"
  Means: What occurred at that past time?
  May be taken as: Search for a variable named 'then' or expect a code continuation pattern
  Say instead: "What occurred at that point in the story?"

## Tips
- Avoid 'then' when describing sequential steps to a model; use 'first', 'next', 'after that' instead
- In programming contexts, say 'promise.then' or 'the then method' to be explicit about the JavaScript sense
- For logical implication, say 'implies' or 'it follows that' rather than 'if...then'
- When telling stories or giving history, use time markers like 'at that point' or 'afterward'
- If you mean a shell script 'if-then', write it as code or say 'the then clause in bash'

## Often confused with
- than: comparison, not sequence
- when: specific time point, not consequence
- next: immediate succession without causation
- therefore: conclusion only, no time element
- catch: error handling in promises, not success continuation
- finally: cleanup regardless of outcome, not sequential next step