Many people do not understand the concept of Alice's power to see the future.
"She can see into the future, although what she sees is based on decisions being made; thus, she must wait for a decision to be firmly rooted in the mind, or acted upon, before she can see the end result.
Alice Cullen See's the future
Her talent is limited to humans and vampires because she has been both; she cannot see the futures of werewolves or hybrid vampires."―Entry on Alice's gift[src]
Alice's power works by receiving visions of the future, sometimes at will. At first she couldn't control them, but she gained it during her growth as a vampire. She can use it to keep tab of an object's decisions by merely focusing on it. She has also described that some visions come to her when there is a connection between her and the source of the vision; whether it be a threat to her family or simply someone she relates to.
She can focus on several objects at the same time, though only as much as her mind can comprehend. Several visions can come to her if the situation forces more objects together.
In Eclipse, Alice explains that since her visions are no illusion of the mind, but rooted into reality, therefore she can see Bella's future.
Alice's views are subjected. They are based on peoples decisions, which is why Alice see's Bella a
Alice and Jasper
s a vampire. Her vision changed when Edward decided to suck the venom out of her.
- ---- JASPER AND ALICE FOREVER ---
- By AliceCullenJasper.