Well, if you replace welfare with jobs, most would agree it's a positive more. Major conglomerates will not go for this, so it becomes a low cost financing for main-street and small to mid size manufactures. I doubt any currently available goods will be effected, price wise because it'd be less that 1/1000 of the products in any given space. It would encourage continued energy product, of all kinds, here in the USA.

"You have to argue that the gain of manufacturing jobs will be worth more than the loss of inexpensive manufactured goods. The market currently says that argument is false"

Huh? Wrong. Nothing currently being manufactured would be effected until thousands of new manufacturing plant are brought (back?) online here in the USA. Your you must prove your idealized statement is valid by your metrics; and it is not.

So let's say there is tariff on imported oil at 10$ per barrel. This means that US companies will buy oil locally, which means that all domestic oil producers can raise oil prices by 9$ and still be competitive on domestic market. But that means that cost of production will raise for US companies. Reduced margins (or lower profits) will force domestic companies to reduce work force.

As you can see tariffs on imported goods can have negative effect on domestic jobs.