There are all kinds of empirical examples of where that relationship hasn't been proven to hold, including in the United States, where they're down to a situation where they have basically less than 5% unemployment, and their inflation rate is not a whole lot greater than ours.
On peut citer toutes sortes d'exemples empiriques contredisant cette relation de cause à effet, notamment celui des États-Unis où le taux de chômage est tombé à moins de 5 p. 100 sans que le taux d'inflation y soit nettement supérieur au nôtre.