So far, there is no inconsistency in the theory of measurement. However, Wigner then learns (by asking his friend again) that the feelings/ thoughts of his friend about the measurement outcome had been in the friend's mind long before Wigner had asked about them in the first place. Therefore, the correct wave function for the joint system of spin and friend just after the interaction must have been either formula_20or formula_24, and not their linear combination. Hence, there is a contradiction, specifically in the "consciousness causes collapse" interpretation.