IP and the incentive argument

It is often claimed by pro-IP advocates that IP gives incentive for people to invent. What ist he usual counter argument?

It also gives people an incentive to invent new things that can be patented; what isn’t necessarily the same as useful inventions.

Also: competition involves innovation too.

Also: why is it so necessary that we need ‘more’ innovation per se?

I’m sure there are others.

i’ve come to the conclusion that the IP problem is impossible to solve from an economic point of view. Seems an approach based on morality/rights etc is more fruitful.

Supressed interests rates give incentive for people to buy houses. Look how well that one turned out!

What is the difference between those two points of view?

People would have the incentive anyways, plus they wouldn’t have to worry about breaching patent laws and wasting likely billions of dollars on lawyers.

Boldrin and Levine.

Simply ask them to prove this blind assertion.