Hi I am Tyler and i’m in Sal’s Pd 3.  Negative externalities impose a cost on the third parties in a transaction so therefore are negative to them. Positive externalities however, are beneficial to their third parties. Positive externalities benefit the third parties by creating something that is helpful. The government intervenes to regulate externalities because if they do not try and regulate them then the benefits of a policy would begin to outweigh its costs and if that were to happen then the externalities would be very unbalanced and it would not help anything. With that being said if only one party is helped out then only one party would benefit from it which would cause it to be bad.  The government mainly intervenes to keep the externalities at a necessary balance that will equally help both sides.