Simple question which has a complex answer. In most countries you may bring in as much cash as you like BUT over a certain limit you have to declare it and account for it's source. Don't declare it and you run the risk of it all being confiscated.
It's not wise to declare large sums of money in Argentina: you are likely to have it taken off you at gunpoint outside the airport or on your way to your destination.
So how much can you bring in without the obligation to declare it? That depends on the limits imposed by the departure country, the arrival country and any countries you transit through. You may arrive in Argentina with up to USD10,000 without declaring it. However if you depart from or transit through Brazil, their limit is 10,000 Reales which is less than USD2000. USA sets a limit of USD10,000 but that is per group travelling together so if you are with another 3 people that's only USD2,500 each.
So, check the limits for your departure and transit countries but in any case, remember that the threshold in Argentina is USD10,000