Insisting on digging deeper the hole you are standing in constitutes evidence of psychological decline. U.S. policy toward Iran is an example so obvious that even hardline Israeli intelligence officials are getting nervous.
The possibility of American decline has traditionally been seen by Americans as virtually impossible by definition, at least in recent decades. Americans tend not to remember anything much further back than that, but I would guess that those who survived the Great Depression might occasionally have experienced some doubt about the "inevitability" of progress in America. Over the last decade, the disastrous mismanagement of the so-called "war on terror" and the U.S. financial system and the environment (remember the poisoned Gulf of Mexico??) have awakened more than a few of the "other 99%" to the realization that since we the people built the U.S., we the people can logically also wreck it: whether you find this good news or bad news, the fact is that the U.S. did not evolve through some inevitable natural phenomenon; we created it through a lot of hard work and more than a little moderate, open-minding thinking of the type that today seems in scarce supply. Therefore, we the people (and perhaps occasionally even a politician or two) ought to be evaluating our society every waking minute for signs of cracks in the facade of everlasting progress. You can't fix it if you don't know it's broke.
In a previous introductory effort to examine the possibility of American decline, I identified several signs of wear, of which one was Washington's "declining ability to design the appropriate tools for international conflict resolution." Assertions of this type are easy to justify with selected evidence but extremely difficult to measure accurately. Face validity for the assertion may be provided by the failure to deal effectively with the long, slow build-up of al Qua'ida, the war on terror, the endless cancer of the Palestinian-Israeli conflict that American bias has so needlessly intensified, and the clueless 30-year-long failure by Washington to devise an effective policy toward Iran. Compared to the defeat of Hitler (even if primary credit for that goes to the USSR), the democratization of Germany and Japan, and the peaceful resolution of the Cold War, U.S. foreign policy over the last 15 years or so does indeed appear second-rate. Nevertheless, the assertion that American foreign policy is declining in effectiveness and constitutes evidence of a broader decline deserves constant reevaluation until conclusively demonstrated to be false.
In that context, Washington's continuing insistence on pursuing a hard-line policy of threats, discrimination, and marginalization toward Iran that is demonstrably not working constitutes one of the most significant pieces of evidence. The gap between stated goals and the negative-sum methods Washington insists on employing to achieve those goals has now become so clear that even the toughest of the Israeli national security elite, most prominently recently retired Mossad chief Meir Dagan, are beginning to lay their reputations on the line to raise the red flag of warning against emotion-driven politicians who are treading too far down the slippery slope to disaster.
The point here is not that Dagan has suddenly become soft or liberal, but that he seems to feel that he must, to protect his country, make the public distinction between zero-sum policies (i.e., policies that either help Israel or Iran) and negative-sum policies (i.e., policies that harm both sides). Dagan, in the face of a torrent of insults from Israeli war-party politicians, has recently reiterated his warning that an Israeli attack on Iran would risk disaster for Israel. American politicians, like many in Israel, have great difficulty today distinguishing between steps that protect national security and steps that undermine it even though they demonstrate "toughness." The option of offering Iran a compromise exists but does not even appear to occur to Dagan, who--as the apparent leader in recent years of undeclared Israeli war on Iran (via terrorism)--has given no evidence of willingness to compromise with Iran but is staking his political future on avoiding self-defeating risk-taking. In other words, like other conservatives, he rejects a positive-sum outcome, but like responsible leaders of all hues also rejects irresponsible policies that are likely to turn out to be negative-sum (an outcome that can only be detected by those who make the effort to think about the long term).
To determine whether the U.S. is governing effectively or entering a period of decline, one of the key pieces of evidence will be the quality of its policy toward Iran.