Purposes and results: in order to, so as to, etc

This lesson explains how English expresses purpose (why someone does something) and result (what happens because of an action). You will learn common connectors and structures used in formal and informal contexts, and how to choose between them.

• Purpose connectors: to, in order to, so as to, so that — they answer 'why'.
• Result structure: so + adjective/adverb + that — it shows the consequence of an action.
• Some forms require an infinitive, others a full clause with a subject and verb.

Remember the difference: purpose explains why; result shows what happens because of an action.

• Use 'to', 'in order to', or 'so as to' + infinitive to express purpose without a subject change.
• Use 'so that' + clause when the purpose requires its own subject or modal (can, could, will, would).
• Use 'so + adjective/adverb + that' to express a result or consequence.

If you need a subject or modal verb in the purpose clause, choose 'so that'.

Watch out for these universal errors when expressing purpose and result.

• Confusing purpose connectors with result structures (e.g., using 'so that' when you mean consequence).
• Using 'so' alone when a clause with 'that' is needed for the result: say 'so that' or 'so + adjective + that'.
• Omitting the subject or modal in clauses where it's required (e.g., incorrect: 'I left early so I could catch the train' is fine, but not when you need 'so that he could').
• Using infinitive forms when the full clause is necessary to show a different subject ('I asked him to leave' vs 'I asked that he leave' in formal contexts).

If two different subjects are involved, prefer 'so that + subject + verb' or 'in order that' in formal writing.