what is the difference between negative and positive externalities
Externality Voluntary exchange is by definition mutually beneficial to both business parties involved, because the parties would not agree to undertake it if either thought it detrimental to their interests. However, a transaction can cause effects on third parties without their knowledge or consent. From the perspective of those affected, these effects may be negative (pollution from a nearby factory), or positive (honey bees kept for honey that also pollinate neighboring crops). Neoclassical welfare economics asserts that, under plausible conditions, the existence of externalities will result in outcomes that are not socially optimal. Those who suffer from external costs do so involuntarily, whereas those who enjoy external benefits do so at no cost.
Positive liberty Although Isaiah Berlin's essay "Two Concepts of Liberty" (1958) is typically acknowledged as the first to explicitly draw the distinction between positive and negative liberty, Frankfurt School psychoanalyst and Marxist humanistic philosopher Erich Fromm drew a similar distinction between negative and positive freedom in The Fear of Freedom (1941), predating Berlin's essay by more than a decade.