Harriet Harman wants to make it illegal to buy sex. Call me an autistic economist, but I'm with Rachel and Not Saussure on this - not only should buying sex not be illegal, but prostitution should be much less restricted than it currently is.

The first rule of economics is that trade benefits both parties - that's why people do it. So, why is the trade in sex different? I don't find the arguments persuasive.

1. "Prostitutes are forced into the business by their poverty, drug addiction or by gangsters who control the trade in illegal immigrants."

There's much truth in this. But this is not an argument for criminalizing prostitution. It's an argument for giving women more options. The solutions instead are: a citizen's basic income; cheaper drugs - through legalizing that trade too; help for addicts; or freer immigration.

In the absence of sensible policies to help desperate women, prostitution is their least bad option. Why deprive them of the chance to make the most of it?

2. "Prostitution exploits women."

It does, insofar as it takes advantage of desperate people. But so do many other capitalist acts between consenting adults. Ordinary employers exploit people's need to earn a living. The difference between my renting my brain to my employer and a prostitute renting her body is only a matter of degree.

3. "The only thing that separates having sex with a prostitute from rape is a cash transaction."

Yes, this clown really said this. But this is just absurd. The only thing that separates shopping from theft is a cash transaction.

4. "Prostitution embodies a view of women which is intrinsically brutalising, dehumanising and predatory. That is why the violence to which it gives rise is routine. That is why it is so appalling that anyone should be arguing that it should be regularised and thus condoned." (Mel P)

It's probably true that the men who visit prostitutes are disproportionately likely to regard them as mere objects, and thus disproportionately likely to assault them. But criminalizing prostitution exacerbates this problem in three ways. It deters more law-abiding, moral, men from visting prostitutes, thus exposing the latter to more dangerous men. It stigmatizes prostitutes, thus helping to legitimize violence towards them in the perverted eyes of their attackers. And it deters prostitutes from reporting their attackers to the police.

5. "Prostitution devalues the true and special meaning of sex."

I don't get this. Lots of things are very special and valuable: music, art and intellectual endeavour. But we see no problem in paying musicians, artists and intellectuals.

So, I suspect hostility to prostitution owes more to mere taste - what Alvin Roth calls repugnance (pdf) - than to a rational assessment of the costs and benefits of the business.