could you tell me how I can prove to this person at my school that the philosophy theory of why we are alive is false

Your question is not clear.

If by ?why we are alive is false? you mean that we have another destination to that the hereafter, there there are numerous ways of proving this. Allah Ta?ala says in the Qur?aan, ?Were you not a drop of liquid and He created you in the most strongest forms. Similarly, we will all die and after dying we will be resurrected and give account for our deeds before Almighty Allah.?

and Allah Ta'ala Knows Best

Mufti Ebrahim Desai