Property is theft!

If I were asked to answer the following question: What is slavery? and I should answer in one word, It is murder!, my meaning would be understood at once. No extended argument would be required . . . Why, then, to this other question: What is property? may I not likewise answer, It is robbery!, without the certainty of being misunderstood; the second proposition being no other than a transformation of the first?

The proprietor, the robber, the hero, the sovereign — for all these titles are synonymous — imposes his will as law, and suffers neither contradiction nor control; that is, he pretends to be the legislative and the executive power at once . . . [and so] property engenders despotism . . . That is so clearly the essence of property that, to be convinced of it, one need but remember what it is, and observe what happens around him. Property is the right to use and abuse . . . if goods are property, why should not the proprietors be kings, and despotic kings — kings in proportion to their facultes bonitaires? And if each proprietor is sovereign lord within the sphere of his property, absolute king throughout his own domain, how could a government of proprietors be any thing but chaos and confusion?

In writing this memoir against property, I bring against universal society an action petitoire [a legal claim to title]: I prove that those who do not possess to-day are proprietors by the same title as those who do possess; but, instead of inferring therefrom that property should be shared by all, I demand, in the name of general security, its entire abolition. If I fail to win my case, there is nothing left for us (the proletarian class and myself) but to cut our throats: we can ask nothing more from the justice of nations; for, as the code of procedure (art 26) tells us in its energetic style, the plaintiff who has been non-suited in an action petitoire, is debarred thereby from bringing an action possessoire. If, on the contrary, I gain the case, we must then commence an action possessoire, [a legal repossession] that we may be reinstated in the enjoyment of the wealth of which we are deprived by property. I hope that we shall not be forced to that extremity; but these two actions cannot be prosecuted at once, such a course being prohibited by the same code of procedure.

—Pierre-Joseph Proudhon, What is Property?

You can go through this issue here and here.