Imo it means that two people who have opposing views collide and become contaminiated with one another if they communicate disagreement. Even if by means of communication one player decides to agree with the oppenents postulate anout something the original postulate he had then became contaminated or in other words it changed his original idea from one to another. For example, He loved bread but someone said there is arsenic in it and he doesn't like arsenic because its poison and thus his postuale changed and he doesnt eat bread because of the opponents view.