So and therefore: results, decisions and conclusions

The idea

Use reason, so + result clause: the result comes second. Therefore can begin a new sentence or follow a semicolon between complete clauses. It is common in formal explanations. Because introduces the reason instead.

Examples

• The batteries were flat, so the torch did not work.
• There were no seats left, so we stood near the door.
• The north entrance is closed. Therefore, visitors must use the side gate.
• The fabric shrank; therefore, the cover no longer fits.
• All three keys are here. Therefore, no key from this set is missing.
• The lift was broken, so we carried the boxes upstairs.

Watch out

Do not automatically pair because with so: choose Because X, Y or X, so Y. In standard edited writing, a comma alone cannot join two complete clauses with therefore. A result word signals a connection; it does not prove that the reasoning is sound.

Try it yourself

1. Choose the correct option. The batteries were flat, ___ the torch did not work. (so / therefore)

   Show answer or example answer

   so

   So joins the reason to its result. For therefore, the given comma would need to become a full stop or semicolon.

2. Choose the correct option. The north entrance is closed. ___, visitors must use the side gate. (Therefore / Because)

   Show answer or example answer

   Therefore

   Therefore, introduces the consequence of the closure in a new sentence. Because would introduce a reason clause instead.

3. Choose the correct option. Because the lift was broken, ___ carried the boxes upstairs. (we / so we)

   Show answer or example answer

   we

   Choose we: Because already links the reason to the main clause. Do not add so before that main clause.

Use it today

Describe one practical problem and the action it caused using so. Rewrite it with therefore and suitable punctuation. Underline the reason and circle the resulting action in both versions.