When to use "pour" when saying "in order to"?

Question

Example:

J'irai à Londres mercredi prochain avec mes parents acheter les nouveaux livres.

Now, I saw this in a book. I would have thought it would be

... avec mes parents pour acheter les nouveaux livres.

Why am I mistaken, and/or what is the rule?

Answer 1

Both sentences are correct.

• If you use pour then “pour acheter les nouveaux livres” is a complement which gives a reason. The verb “aller” is then understood as “to go”.

• If you don't, “acheter les nouveaux livres” is then the direct object of “irai”. It's separated from the verb by 3 other complements: one gives the place, a second one gives time and a third one says how. But you can remove all three to understand the sentence: “J'irai acheter les nouveaux livres”. Here, the expression “aller faire quelque chose“ is used in the future tense.