On Wednesday, Jonathan Cohn asked if Paul Ryan's address was "The Most Dishonest Convention Speech ... Ever?"  Now that Mitt Romney had his turn, I decided to answer the question.
After reviewing presidential and vice-presidential nominee acceptance speeches throughout the era of the modern Republican Party, back to 1980, I present to you: the Top 13 Republican Convention Speech Lies.
To make this list, the candidate had to deliver a stone-cold, unequivocal, shameless brazen lie. Being misleading but technically true, or using disingenuous qualifiers wasn't good enough.
For example, Vice-President Dick Cheney does not make the cut for saying in 2004  "we dealt with a gathering threat and removed the regime of Saddam Hussein" shortly after saying "the president made clear that the terrorists would be dealt with". Sure, he's suggesting a false connection between 9/11 and Iraq, but he didn't explicitly state the lie ... at least, not on the convention stage.
With that in mind, here we go.
13. Bush 2000: The Gore Invented The Internet Lie
George W. Bush wrapped the lie in a joke, but it's still a lie.
After riffing about all the inventions in history Gore would call a "risky scheme," -- a way to deflect criticism of his own conservative proposals -- Bush said, "if he'd been there when the Internet was invented ... well, I understand he actually was there for that." 
It's about as good as a birth certificate joke. And just as much of a lie.
12. Bush 1992: The Clinton Will Raise Your Taxes Lie
George H. W. Bush also sought to wrap his lie in a joke.
Bill Clinton campaigned on raising taxes for the "wealthy"  and cutting taxes for the "middle class." He did not precisely define the income levels for those terms. But there was nothing in his platform that justified Bush saying, "He says he wants to tax the rich. But folks, he defines rich as anyone who has a job." 
As it happened, Clinton largely followed through on his promise , raising taxes only on household income over $140,000 a year, and on individual income over $115,000 (note that these values are in 1993 dollars). While deficit concerns persuaded him not to push for a broad middle-class tax cut, he did expand the Earned Income Tax Credit.
11. McCain 2008: The Original ObamaCare Lie
Sen. John McCain started the health care lies early , saying: "His plan will force small businesses to cut jobs, reduce wages, and force families into a government-run health care system where a bureaucrat stands between you and your doctor."
Of course, Obama's proposal then, as his law now, included exemptions for small businesses  from complying with coverage mandates, as well as special tax credit. And there never was a plan to force anyone into a "government-run" system  or have bureaucrats meddle with medical decisions.
10. Palin 2008: Bridge To Nowhere? Who Me?
You might not remember this, but there once was a woman named Sarah Palin who was nominated for vice-president.
And there was once as a public works projects that was pilloried as the "Bridge to Nowhere" because of how few people it serve in a remote part of Alaska.
In her acceptance speech, Palin claimed to be above grubbing for such pork , saying, "I told the Congress, 'Thanks, but no thanks,' on that bridge to nowhere."
Except that she had campaigned for governor supporting the project in 2006 , then accepted federal funds that were available to used on that bridge. She chose to divert the funds to other transportatation projects, she did not send the money back saying "no thanks."
9. Bush 2000: The Not Ready For Duty Lie
This is a rare case of a lie that the campaign felt obliged to retract.
Three weeks later, Cheney conceded  in a series of interviews that the statement was based on outdated data and any such readiness problem was brief and had been corrected.
Though he still sought to maintain, "the military is in decline" under the Clinton administration.
8. Romney 2012: The Apology Tour Lie
Romney said: "I will begin my presidency with a jobs tour. President Obama began with an apology tour.  America, he said, had dictated to other nations. No Mr. President, America has freed other nations from dictators."
This is perhaps the dumbest lie, but a lie nonetheless. Obama has never gone to another country and apologized on behalf of America, ever. 
Furthermore, Obama played a direct role in dislodging dictators in Egypt  and Libya , without misguided unilateral military action, without suffering the international backlash we did following Bush's invasion of Iraq.
So he really doesn't need a lecture on the subject from an opponent with no foreign policy experience at all.
7. Reagan 1984: The Social Security Tax Lie
In the summer of 1984, Reagan's re-election campaign got a little shaky after Democratic nominee Walter Mondale said at his convention: "Mr. Reagan will raise taxes, and so will I. He won't tell you. I just did." 
As I wrote in my book "Wait! Don't Move To Canada!,"  this gambit caught the Reagan team off guard: "[The campaign] couldn't get its story straight whether it was promising no tax hikes in the second term no matter what, or leaving the door open a crack for a change in course." Mondale cut Reagan's lead by 6 points in one poll and took the lead in another.
Some who spoke so loudly in San Francisco of fairness were among those who brought about the biggest single, individual tax increase in our history in 1977, calling for a series of increases in the Social Security payroll tax and in the amount of pay subject to that tax. The bill they passed called for two additional increases between now and 1990, increases that bear down hardest on those at the lower income levels.
The Census Bureau confirms that, because of the tax laws we inherited, the number of households at or below the poverty level paying Federal income tax more than doubled between 1980 and 1982. Well, they received some relief in 1983, when our across-the-board tax cut was fully in place. And they'll get more help when indexing goes into effect this January.
But his description of the "amount of pay subject" to the 1977 tax referred to an increase of the payroll tax cap , subjecting more wealthy income to Social Security taxes and making the overall system more progressive.
Now that by itself would not meet our strict lying standards. Misleading perhaps, not outright prevarication.
But then Reagan went on to say "they received some relief in 1983, when our across-the-board tax cut was fully in place." That is false. As Paul Krugman pointed out back in 2004, Reagan's income tax cuts for "many middle- and low-income families" were negated by Reagan's own Social Security payroll tax increase.  And his was regressive, not progressive.
... the Social Security Reform Act of 1983 [included] an increase in the payroll tax that pays for Social Security and Medicare hospital insurance. For many middle- and low-income families, this tax increase more than undid any gains from Mr. Reagan's income tax cuts. In 1980, according to Congressional Budget Office estimates, middle-income families with children paid 8.2 percent of their income in income taxes, and 9.5 percent in payroll taxes. By 1988 the income tax share was down to 6.6 percent -- but the payroll tax share was up to 11.8 percent, and the combined burden was up, not down.
6. Ryan 2012: The GM Plant Lie
Obama has been hammering Romney for opposing his successful efforts to save the America auto industry. So Ryan tried to whitewash that by blaming Obama for a GM plant that announced its termination before he took office.
Ryan said:  "Right there at that plant, candidate Obama said: 'I believe that if our government is there to support you … this plant will be here for another hundred years.' That’s what he said in 2008. Well, as it turned out, that plant didn’t last another year. It is locked up and empty to this day ... the recovery that was promised is nowhere in sight."
Well yes, the government wasn't there to support the auto industry ... in 2008, before Obama became President , when the announcement was made to close the plant.
Further, those comments were made before there was any talk of a "recovery" because they were made in February 2008, before the financial crisis, before the Great Recession that pushed the American auto industry to the brink of extinction.
5. Bush 2004: The Weapons Inspectors Lie
Grappling with the unpopularity of the Iraq war, President Bush sought to deflect that charge that he had gotten American stuck in a foolhardy war of choice, saying "After more than a decade of diplomacy, we gave Saddam Hussein another chance, a final chance, to meet his responsibilities to the civilized world. He again refused." 
But Saddam did not refuse to let international inspectors in. After inspectors were struggling to find anything, Bush forced the inspectors out before they could formally conclude that Saddam was not stockpiling weapons of mass destruction.
Yet the claim is still embraced by Republicans today. In fact, FactCheck.org dinged Mitt Romney in 2007 for repeating it: 
That the U.N.'s International Atomic Energy Agency was not permitted to make inspections might come as a bit of a surprise to Mohamed ElBaradei, head of the IAEA, who reported on March 17, 2003, that "late last night...I was advised by the United States government to pull out our inspectors from Baghdad." Inspectors had been in Iraq since November 2002. They remained until U.N. Secretary-General Kofi Annan ordered their evacuation on March 17, 2003, just three days before U.S. and British troops invaded Iraq.
4. Ryan 2012: The They Stole Your Medicare Lie
Ryan said, "the biggest, coldest power play of all in Obamacare came at the expense of the elderly.  You see, even with all the hidden taxes to pay for the health care takeover, even with new taxes on nearly a million small businesses, the planners in Washington still didn’t have enough money. They needed more. They needed hundreds of billions more. So, they just took it all away from Medicare. Seven hundred and sixteen billion dollars, funneled out of Medicare by President Obama. An obligation we have to our parents and grandparents is being sacrificed..."
He packed many of the health care lies from the right-wing fever swamp into one passage.
That a plan where people choose between private insurance plans somehow is a government takeover. That the law raises taxes on small business when it includes tax credits for small business.  And that shoring up Medicare's solvency by reducing wasteful spending to hospitals and insurance companies  -- reductions which Ryan kept in his own budget -- is somehow the same as cutting seniors' benefits. 
All to falsely turn a plan that strengthens Medicare's financing into one that "sacrificed" our "obligation" to our elders.
3. Cheney 2004: The Kerry Won't Kill Terrorists Lie
Cheney said, "He declared at the Democratic convention that he will forcefully defend America after we have been attacked.  My fellow Americans, we have already been attacked. Senator Kerry denounces American action when other countries don't approve, as if the whole object of our foreign policy were to please a few persistent critics ... George W. Bush will never seek a permission slip to defend the American people."
But Kerry explicitly said "I will never give any nation or any institution a veto over our national security."  And he did not say he would only defend America "after" an attack. He also said he would use force "against a threat that was real and imminent."
Meanwhile, unbeknownst to the public at the time, the Bush administration had already given Pakistan a veto  over any operation to pursue Osama Bin Laden, a policy that ended with President Obama.
2. Ryan 2012: The Obama Did Nothing On Debt Lie
Again, Ryan packed a lot of lies in a short paragraph.
First, the debt commission did not come back with an urgent report. They were three votes short of getting the supermajority support needed  for the report to be sent on to Congress for a vote.
Second, one of members of the commission that voted against the report was Paul Ryan. 
Third, Obama responded to the failure of the debt commission to produce a report by prodding Congress to pass "sequester" legislation forcing $1.2 trillion in automatic spending cuts  if Congress is unable to come up with legislation to produce a similar amount of deficit reduction via spending cuts and tax increases.
Fourth, one of the members of Congress that voted for that legislation was Paul Ryan.
1. Romney 2012: The Middle Class Taxes Lie
Romney said, "unlike President Obama, I will not raise taxes on the middle class." 
This is the big lie. The Full Orwell.
Obama has cut taxes for the middle class, period. Politifact did a comprehensive analysis of all the tax changes made by Obama and concluded:  "The changes to the tax code made under Obama and the analyses by the Tax Policy Center show that for the middle 60 percent of the income distribution, both the average tax paid and the average tax rate fell between 2008 and 2011."
And as it widely known now, despite Romney's furious attempt to deny it, his own stated plans for across-the-board income tax cuts, corporate tax cuts and estate tax repeal, combined with a pledge to offset the cost by ending unspecified tax deductions, is impossible to achieve without raising taxes on the middle class while cutting taxes for the wealthy. 
So, to answer Jonathan Cohn's initial question, with the most outright lies of any Republican nominee's acceptance speech since 1980, Paul Ryan in fact does deserve the honor of "Most Dishonest Convention Speech Ever."
But Romney's audacious attempt to project his own regressive tax plan on Obama, and reject the mathematical truth of Obama's own tax record, deserves the honor of the single biggest convention lie by a Republican nominee for president in modern times.