24	Eric R. Claeys

water has few or no private human uses; it has many common uses, especially fishing and travelling. Similarly, although manure may be used most productively when owned and consumed exclusively, a highway is used most productively when many people are granted rights to travel on it. That difference supplies one of several reasons why Haslem’s manure-gathering did not entitle him to claim he had appropriated the highway.

3.4 The communicative function of productive labour

Separately, labour focuses the scope of property by virtue of having an equality component.66 As A. John Simmons explains:

[T]he right of self-government . . . is . . . a right only to such freedom as is compatible with the equal freedom of others. To try to control for one’s projects external goods that have already been incorporated into the legitimate plans of others, would be to deny to others that equal right. We may make property with our labour only in what is not already fairly taken as ‘part of the labour’ of another.67

Because ‘productive use’ is a normative interest held by political equals, productive labour theory stresses labour’s communicative function much more than contemporary property scholars appreciate. ‘Labor must show enough seriousness of purpose to “overbalance” the community of things’ that exists because ‘the World [was given] to Adam and his Posterity in common’.68 For ‘things of use’, the best way to show that purpose is ‘to use them’.69

This requirement highlights further problems with the tomato-juice hypothetical. Onlookers’ social perceptions of things are keyed to their pre-political normative expectations. That which they expect to contribute to human prosperity, they perceive in entities and combinations whose uses lend themselves to human prosperity. People perceive manure as capable of being owned privately, but they perceive highways as commonses open to all travellers. Similarly, they perceive fish as good candidates for appropriation and ocean water as a bad one. (Note how the ‘ocean’ is a singular entity while ‘fish’ come in separate entities—even though in English the plural for ‘fish’ is identical to the singular.) On one hand, people’s perceptions of ocean water accord with their expectations that the water be used as a common pathway; on the other hand, these perceptions accord with the fact that it would be extremely difficult, by labour or any other marker, to ‘put a distinction between’ a few water molecules and the ocean remaining in ‘common’.70 Radioactive carbon atoms do not adequately overcome these boundary-marking problems. Our intuitions suggest that the can owner abandons the juice by pouring it because it is impossible to keep the juice separate from a resource best left in common.

66	Locke 1689b, Second Treatise, s. 4, p. 269.	67	Simmons 1992, 275.
68	Locke 1689b, Second Treatise, s. 25, p. 286.	69	Simmons 1992, 272.
70	Locke 1689b, Second Treatise, s. 28, p. 288.