# Propensity to Truck, Barter, and Exchange

## Definition

An innate or fundamental disposition in human nature to negotiate, trade, and
exchange goods with others. Smith identifies this propensity as the ultimate
cause of the division of labour, arguing that it is unique to humans and
absent in all other animal species. He leaves open whether it is a primary
instinct or a consequence of the faculties of reason and speech, but treats
it as the foundational mechanism from which specialisation and economic
organisation emerge.

## Source Chapter

Book I, Chapter 2: "Of the Principle which gives Occasion to the Division
of Labour"

## Context

This is the central thesis of the chapter. Smith argues that the division of
labour "is not originally the effect of any human wisdom" but rather the
"necessary, though very slow and gradual, consequence" of this propensity.
The entire chapter serves to establish exchange as the causal origin of
specialisation.

## Economic Domain

General Theory

## Smith's Original Wording

"This division of labour, from which so many advantages are derived, is not
originally the effect of any human wisdom, which foresees and intends that
general opulence to which it gives occasion. It is the necessary, though very
slow and gradual, consequence of a certain propensity in human nature [...] the
propensity to truck, barter, and exchange one thing for another."

## Modern Interpretation

This concept prefigures the modern economic assumption of rational self-interest
as the basis of market behaviour. It also anticipates evolutionary and
institutional economics debates about whether exchange is a natural disposition
or a culturally constructed institution.
