The author (Austrailan economist William Coleman) lists four justifications for property, and shows that one of them (allocational efficiency) applies to IP er, see below, and two others (justice and incentives) partly. Unfortunately, he does not examine the extent to which his other justification, far from applying to IP, actually tells strongly against it:
3. The economisation of violence: In the absence of a code of property, resources are wasted in force and violence to take possession, and defend possession.
In the modern world, enormously more force, violence and wasted resources (in the form of the policing powers under such legal frameworks as the US DMCA) are needed to maintain copyright than would be used if there were no copyright. This is what has made IP the hot issue that it now is.
To clarify: with physical property, if there is no clear legal ownership, rivals are very likely to fight over it. With legal property ownership, the violence and waste(in the form of crime and policing) is much reduced. With, say, recorded music or computer software, in the absence of legal protection, they will be freely copied; but the attempt to provide legal protection produces a huge wasteful activity of hidden, criminal copying and intrusive, destructive policing in an attempt to prevent it. Thus the "economisation of violence" argument is not merely nullified but entirely reversed.
Correction: in fact, Coleman doesn't say that the allocational efficiency argument supports IP - he starts talking about it and wanders off the point. In fact, like the economisation of violence argument, allocational efficiency tells strongly against intellectual property: the most efficient allocation is for anyone who wants a copy of something to be allowed to make one. Only the justice and (most significantly) incentive arguments have any force in favour of IP.