The rules we follow in the courtroom are designed to help judge and jury ferret out the truth, or something close to it, from a blizzard of often-conflicting evidence.  One of those rules tells us that “statements against interest” – that is, a statement that comes at some cost, disadvantage, or liability to the person testifying - should be accorded a higher degree of credibility. The theory is that the person has nothing to gain, and something to lose, so his main motivation is likely to be simply telling the truth or doing the right thing. On the other hand, when the person has something to gain from making a claim, he might well be telling the truth, but we should probably be skeptical.

Applied to politics, this rule would suggest that it might not be best to form our opinions about a candidate from statements made by his or her opponent or that opponent’s team. Those claims might well be true, but are hardly the most reliable source if we are seeking the truth.

Thoughtful citizens once turned to an independent press, which today largely has been replaced by media sources that act as cheerleader-in-chief in an echo chamber of common belief. Even truly independent and thoughtful sources like PBS Newshour are trapped by the requirement to present “both sides.” So where to turn? 

One approach is to find people making “statements against interest.” Partisans have an enormous interest to see their party take the White House (their interest is defined in terms of jobs, access, influence, power, and money, as well as the prospects for their political agenda). So when party members criticize their own candidate (following the primaries, once he or she is carrying the banner for their side), these are powerful examples of statements against interest and we should afford them a presumption of credibility.

I have been collecting “statements against interest” about Donald Trump made by prominent Republicans after he became their candidate. Here is a selection for your consideration:

50 Former GOP National Security Officials (including former GOP CIA directors, heads of the National Security Agency and Department of Homeland Security, US Trade Representative, etc.):  Trump “would be a dangerous President and would put at risk our country’s national security . . .Mr. Trump lacks the character, values, and experience to be President.  . . . He appears to lack basic knowledge about and belief in the U.S. Constitution, U.S. laws, and U.S. institutions, including religious tolerance, freedom of the press, and an independent judiciary.  In addition, Mr. Trump has demonstrated repeatedly that he has little understanding of America’s vital national interests, its complex diplomatic challenges, its indispensable alliances, and the democratic values on which U.S. foreign policy must be based. At the same time, he persistently compliments our adversaries and threatens our allies and friends . . . He is unable or unwilling to separate truth from falsehood . . . He lacks self-control and acts impetuously. He cannot tolerate personal criticism.  He has alarmed our closest allies with his erratic behavior.  We are convinced that in the Oval Office, he would be the most reckless President in American history.” (August 8, 2016)

Hank Paulson (Treasury Secretary under President Bush):  His “brand of populism [is] rooted in ignorance, prejudice, fear and isolationism . . . Trump is a phony and should not be president . . . . When Trump assures us he’ll do for the United States what he’s done for his businesses, that’s not a promise — it’s a threat . . . In essence, he takes imprudent risks and, when his businesses fail, disavows his debts.  Trump repeatedly, blatantly and knowingly makes up or gravely distorts facts to support his positions or create populist divisions.”  (June 24, 2016)

William D. Ruckelshaus and William K. Reilly (former GOP EPA Administrators): “Donald Trump has shown a profound ignorance of science and of the public health issues embodied in our environmental laws.  He hasn’t a clue about Republicans’ historic contributions to science-driven environmental policy . . .

That Trump would call climate change a hoax—the singular health and environmental threat to the world today—flies in the face of overwhelming international science.”  (August 9, 2016)

David Brooks (Republican columnist): Trump is “a morally untethered, spiritually vacuous man who appears haunted by multiple personality disorders.” (July 29, 2016)

George Will (long-time conservative columnist): Will left the GOP over the Trump nomination.  Before that, he said: “Were he to be nominated, conservatives would have two tasks. One would be to help him lose 50 states—condign punishment for his comprehensive disdain for conservative essentials, including the manners and grace that should lubricate the nation’s civic life.” (April 29, 2016)

Mitt Romney (GOP Presidential nominee 2012): Trump has “a character and temperament unfit for the leader of the free world.” (May 27, 2016)

Karl Rove (Senior Republican strategist): Trump is “a complete idiot” who is “graceless and divisive.”  (June 3, 2016)

Paul Wolfowitz (long-time senior GOP official in various roles, foreign policy advisor to President Bush): Trump “says he admires Putin, that Saddam Hussein was killing terrorists, that the Chinese were impressive because they were tough on Tiananmen Square.  That is pretty disturbing . . .  I certainly think it's important to speak up and say how unacceptable he is. I'm always more than willing to do that. . . .The only way you can be comfortable about Trump's foreign policy is to think he doesn't really mean anything he says. That's a pretty uncomfortable place to be in. Our security depends on having good relationships with our allies. Trump mainly shows contempt for them. And he seems to be unconcerned about the Russian aggression in Ukraine. By doing this he tells them that they can go ahead and do what they are doing. That is dangerous.”  (August 26, 2016)

Susan Collins (GOP Senator): She noted his “constant stream of cruel comments and his inability to admit error or apologize . . . .  But it was his attacks directed at people who could not respond on an equal footing . . .that revealed Mr. Trump as unworthy of being our president.” (August 9, 2016)

Lindsey Graham (GOP Senator): Trump’s attack on Judge Gonzalo Curiel “is the most un-American thing from a politician since Joe McCarthy.  If anybody was looking for an off-ramp, this is probably it. There’ll come a time when the love of country will trump hatred of Hillary.” (June 7, 2016)

Meg Whitman (CEO Hewlett Packard, former CEO of eBay, GOP candidate for Governor of California): It is time for Republicans “to put country first before party.”  Trump is “a dishonest demagogue,” who could lead the country “on a very dangerous journey . . . . Time and again history has shown that when demagogues have gotten power or come close to getting power, it usually does not end well.”  Trump has already “undermined the character of the nation.”  (August 2, 2016)

Sally Bradshaw (GOP operative and author of GOP post-2012 strategy): “I could not abide the hateful rhetoric of Donald Trump and his complete lack of principles.”  (August 1, 2016)

Marc Racicot (Republican National Committee chair, 2001 to 2003): “I cannot and will not support Donald Trump for president.” (August 3, 2016)

Gordon Humphrey (former GOP U.S. Senator from New Hampshire): Trump is “a sociopath, without a conscience or feelings of guilt, shame or remorse.”  (August 4, 2016)

Richard Hanna (GOP Congressman): “For me, it is not enough to simply denounce [Trump’s] comments: He is unfit to serve our party and cannot lead this country.” (August 2, 2016)

Glenn Beck (hard right conservative talk show host):  (The day after the nomination he predicted that because of Trump, the US would not “elect another Republican president ever again.”)  Previously, he had said:  “I don’t want my children to look at that man and say, ‘Yeah, he’s my President.’ I won’t have that. I will not endorse it, I will not tolerate it.”  (May 4, 2016)

George P. Shultz (Secretary of State under Ronald Reagan and Secretary of both Labor and the Treasury under Richard Nixon):  On the prospect of a Trump presidency: “God help us.”  (August 15, 2016)

(Please note that I have given the dates of these statements. Trump was recognized by the RNC as the presumptive nominee on May 3. Statements prior to May 3 made by Trump’s primary opponents or their supporters cannot fairly be considered “statements against interest.” My own collection was supplemented by examples collected by David Graham for The Atlantic’s website.)