my colleague in full disclosure i worked with him on a project recently michael clem are clemmons, talked about trillion dollar bills on the sidewalk there to be picked up if only the united states would just open its door more widely to the world. whoa due you found find these arguments unpersuasive? >> guest: let me start from a broader perspective, okay? there is actually no data whatsoever that would allow anyone in this world to estimate what the impact on global gdp will be for example to open up the borders. all the previous historical experience about mass migration have been due to cataclysmic events, major wars, disasters so on. both histories, even those who find data that tell tests whats happened don't apply today's setting where we want to relax immigration restrictions and let anymore and cross the border whenever they want. so all these trillion dollar bills on the sidewalk are not public to all by economists and by work ought mathematical model. you set up a model and then grind out numbers for the model. any model involves many, many, many assumeses. and whenever an assu