An iris scan does not identify who you are talking to. A fingerprint scan does not either. These are unique to an individual, if they were the person who set them up, then it is, in 99% of cases, a unique element to a person that can be used to authenticate them.
That's a whole of a lot better than a password, which can be shared by multiple people.
That's a whole of a lot better than a password, which can be shared by multiple people.