Calling something old or obsolete does not tell what's wrong with it. What specific evidence do you have that Ricardo was wrong, or that conditions have changed to invalidate his theory?
Contrariwise, there are many studies that show that the best single predictor of economic health for a nation in the last two hundred years is how open it is to trade with the rest of the world. That would seem to completely validate Ricardo.
Newton discovered the Theory of Gravity in the same general time period. We now plot rocket courses with it. Ricardo's theory of comparitive advantage, while not quite so clean and elegant, it is ultimately based in simple mathematics. (See
http://william-king.www.drexel.edu/top/prin/txt/trade/itrade1.html for details.)
Now, you may claim that a simple model does not account for complex conditions, but you must show where it breaks down. For Newtonian physics, the famous three-body problem was never exactly solved for gravitation attraction and motion, though one can use the theory to get estimates that agreed closely with reality. So even when the complexity ramped up, the theory worked.
Then relativity came along, and showed that Newtonian physics failed in some extreme circumstances (particularly high velocity). The theory was refined by Einstein for those extreme conditions. This did not affect the theory for routine cases.
So - where do you think Ricardo's theory is breaking down? What evidence do you have? Note that anecdotes don't count - you have to provide evidence about overall or aggregate effects, since that's what Ricardo's theory talks about.
And how do you explain that the US unemployment rate has dropped since NAFTA was implemented? How do you explain how protectionist regimes like Japan have such terrible economic problems? (They have protected their internal industries for decades, and run a huge trade surplus. If Ricardo were wrong, then they would be doing great, right? But they're not - a fifteen year recession so far. Why?)
I know you anti-free-trade guys want in your hearts desperately for the facts and the economic theory to support you. Unfortunately for you, they don't. (Fortunately for the rest of us, because open trade is the source of much of our wealth as a society.)
Calling something old or obsolete does not tell what's wrong with it. What specific evidence do you have that Ricardo was wrong, or that conditions have changed to invalidate his theory? The present economic trends are a case in point. Notice that the economists who attempt to make job predictions are consistently wrong. This at least suggests a flaw in the theories they apply.
Then relativity came along, and showed that Newtonian physics failed in some extreme circumstances (particularly high velocity). The theory was refined by Einstein for those extreme conditions. This did not affect the theory for routine cases.
As you so aptly point out, Newtonian physics breaks down in extreme conditions. The economies are far larger today than was the case in 1823. The speed and efficiency of the transfer of capital and information has also changed. My premise is that as the economies represented by Ricardo's underlying assumptions have changed from those he was familiar with, the theories he promulgated may have become inaccurate.