Compare a price discriminating monopoly to a perfectly competitive industry in terms of efficiency.?

Question

Compare a price discriminating monopoly to a perfectly competitive industry in terms of efficiency. Which of these two market structures is best for society?

Answer 1

Both produce at the efficient quantity and maximize total surplus.  Their last good is produced where price equals marginal cost.  

In terms of total surplus, one could argue that they are both equally beneficial to society.  However, in p-d monopoly, all the surplus is producer surplus; there is no consumer surplus.  So one could also argue that perfect competition is better, since it splits the surplus among consumers and producers.

If we're talking in the real world, however, perfect competition is far better.  Since we have not yet perfected mind reading technology, a monopolist would have to waste considerable time and money in interviewing or observing each customer to find out how much they're willing to pay.