If I order and buy a bunch of articles from someone in a foreign country and pay him with Paypal, does he have to pay taxes?
Generally tax liability falls due in the country in which the person who carries out the work lives. If the person is taxed on their world wide income (as they are in the States) that's more complex, but broadly speaking they pay tax to their authorities. You don't need to worry about your responsibility.
You could pay him in cash check money order etc. How he gets the payment does not matter. If the law states they have to pay tax on earnings.... then they have to pay tax on earnings. Doesn't matter how they are paid......