Which belief do Polonius instructions to Reynaldo demonstrates

The character of Reynaldo shows up in Act II, Scene 1. In that scene, Polonius asks Reynaldo to go to Paris. While he is there, his job is going to be to spy on Laertes, the son of Polonius. Polonius wants Reynaldo to spy on Laertes because he is not sure Laertes will behave himself in Paris.