Something like 90% of world commerce is on the oceans, and there are around 8 or 10 "choke points" that need to be kept open. (Suez and Panama canals, Straits of Hormuz, Straits of Malacca, Straits of Gibraltar, Bab el Mandeb, etc.) And we can't depend on, say, the Chinese to keep commerce flowing around Korea, the Philippines, Japan, etc. So it's not just a matter of how powerful the individual ships are, but how many ships we have.
For every big aircraft carrier, we need a LOT of other ships - subs, cruisers, destroyers, oilers, various cargo and troop carriers, minesweepers, and so forth and so on.
How many? Don't ask me, I can't put a number on it. But at about half the size of Reagan's "600 ship" navy, I can at least wonder if we've cut too much.
And Obama's deflection of Romney's comment - questioning the size of our navy with references to horse cavalry and infantry bayonets - falls into the category of ignoratio elenchi - an irrelevant conclusion, the fallacy of presenting an argument that may be valid, but which doesn't address the issue at hand. I was taken to task in grammar school for doing this in a school assignment, so it's a bit disheartening to see it coming from the leader of the Free World.
