What exactly did Standard and Poor's say. The answer is as follows:
Obviously, the size of the debt had something to do with the downgrade, so it would probably be tendentious to call Sen. Paul a bald-faced liar.. But, just as obviously, it is the pessmism about the capacity of the national government of the United States to work effectively to meet whatever challenges are involved that more substantially explains the downgrade. Default is threatened not because the US economy is too weak to cover all of our debts (especially if taxes are raised relatively modestly for those of us in the top 1%), but because a group of Republican terrorists in the House, led, alas, by the junior senator from Texas, have determined that they would rather (threaten to) bring down the international economic order than to behave as responsibly as many Senate Republicans (excluding, of course, the junior senator from Texas) apparently wish to. It is not, contrary to their whining, the obdurate failure of President Obama to bargain. It is, rather, that he is not going to submit to political terrorism, and he is correct.
Incidentally, with regard to his vote while senator against raising the debt ceiling. I take it that all of us can recognize the difference between political posturing, which I presume he was doing, and genuine "decision making," when one realizes that more than posturing is at stake. Anyone who voted against raising the ceiling knew to a certainty that it was going to pass. It was a costless vote, in term of the stakes for the US. Quite frankly, it is comparable to the posturing of House Republicans back in 1998 to impeach Bill Clinton, since they knew to a near certainty that he would never be convicted by the Senate. If the House had truly been the decisionmaker, I wonder how many Republicans would have voted to replace Bill Clinton with Al Gore, who would therefore be allowed to run as the incumbent in 2000 (and be eligible for re-election as well in 2004, since he wouldn't be taking over until after the the first half of the second term). One of the realities of our political system--perhaps any political system--is that it generates all sorts of incentives for strategic voting designed to appeal to one's base, taking in the knowledge that the vote will in fact have no impact. (This may be especially true, for example, when presidents make credible threats to veto legislation: Why not let the President take the heat for saying no to something one's constituents want (but really shouldn't have?)
The rise of "war rooms" in campaigns have made such symbolic votes more-and-more important, especially in primaries, even if they often have little or nothing to do with actual governance. Perhaps Obama would have taken us into default if he were the 51st vote (since Dick Cheney would have broken a tie), but I respectfully doubt it. We know that almost none of the Republican senators (other than the egregious junior senator from Texas) really want to be the decisive vote to do so. Would Rand Paul really do it, or is he, too, posturing and presenting himself as more stupid than I suspect he is with regard to the potential consequences of default. After all, he is clearly going to run for President in 2016, and perhaps he will leave the Tea Party crazies (who I would like to think are a minority of the Tea Party itself) to the junior senator from Texas). But maybe not? But who will provide votes 41+ to prevent the vote: McCain, Graham, Alexander, Portman, Collins, Kirk, even Hatch, who was just re-elected and surely doesn't plan to run for re-election in 2018.