Putting words in the mouths of respected figures is as old a practice as man. The reasons vary; sometimes the idea is to knock the venerated figure off his pedestal, while other times the idea is to invoke what he purportedly "said" as an argument to authority in support of one premise or another. Sometimes, this is relatively harmless; it really shouldn't much matter whether George Washington admitted to his father that he chopped down that cherry tree with his little hatchet, because what he did or didn't do as a boy is of little consequence. However, I didn't enjoy learning that the story I had been told about him was a myth, as it deepened my suspicions that I was being lied to about a lot of other things. (If you think about it, making up a story about the father of the country and promulgating that as a national moral lesson for children might not be wise.)

OTOH, it might have been good for me to learn that at a relatively early age that one of the core national narratives was a lie. It is healthy to be skeptical -- especially when the skepticism involves an argument to authority.

Like it or not, the dishonest cherry tree narrative shaped my character, and helped form such lifelong cynicism that even today, the "cherry tree" goes off whenever I am subjected to a quote from a respected authority figure which just sounds too, um, "good to be true." A recent example was the Einstein bee quote:

"If the bees should die, humankind would have but four more years to live."

"I would rather believe two Yankee professors would lie, than that stones have fallen from the heavens."

Clayton Cramer has been debunking dubious quotes attributed to the founders, and he notes that this one dates from 1902:

Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master. -- George Washington

For his research, Cramer has been relying on the Thomas Jefferson papers and the George Washington papers. These are great resources, and I thought I would try my luck with the quote about the lying Yankee professors. While I could find not a single example of Jefferson ever using the word "Yankee," it was used three times in letters to Jefferson -- all of which were written by William Short. A fellow Virginian, Short was so close to Jefferson that he was called his "adoptive son," and served as a diplomat in a number of posts. I think it is significant that Short used the term to distinguish Americans from foreigners and not to distinguish Northerners from Southerners, which the meteor quote seems to imply. During the early history of the country, the term was used by the British to describe all Americans, and it does not appear to have been widely used to deprecate Northerners until the Civil War.

So it seems very unlikely that Jefferson would use that term in a demeaning manner to characterize either American professors in general, or professors from the North in particular. All the more so if we consider a letter to Jefferson from Professor J. Wheatcroft dated September 29, 1803, and detailing a "Report on Meteors Over Normandy":

An account of a Meteor which passed over Normandy, and let fall Shower of Stones in the environs of Laigle

So it seems quite likely that Jefferson knew about meteors and had read Wheatcroft's detailed scientific account, and there is nothing to indicate that he would have considered him a Yankee liar. Moreover, because the report he forwarded originated with French scientists, it seems more likely that a skeptical Jefferson might want to believe that French (as opposed to "Yankee") scientists were lying.

This is not to say that Jefferson was not above scientific skepticism. He approached science itself with skepticism, and in a letter to Caspar Wistar (professor of anatomy, midwifery, and surgery, and later chair of anatomy at the University of Pennsylvania) he expressed misgivings about the practice of medicine going too far, with doctors experimenting on patients to prove the "bewitching delusions of their theories."

While he didn't say anything about marijuana or hemp, Jefferson did note that opium cures "watchfulness" (archaic for insomnia). From his letter to Caspar Wistar, June 21, 1807:

....We know, from what we see & feel, that the animal body in it's organs and functions is subject to derangement, inducing pain, & tending to it's destruction. In this disordered state, we observe nature providing for the re-establishment of order, by exciting some salutary evacuation of the morbific matter, or by some other operation which escapes our imperfect senses and researches. She brings on a crisis, by stools, vomiting, sweat, urine, expectoration, bleeding, &c., which, for the most part, ends in the restoration of healthy action. Experience has taught us, also, that there are certain substances, by which, applied to the living body, internally or externally, we can at will produce these same evacuations, and thus do, in a short time, what nature would do but slowly, and do effectually, what perhaps she would not have strength to accomplish. Where, then, we have seen a disease, characterized by specific signs or phenomena, and relieved by a certain natural evacuation or process, whenever that disease recurs under the same appearances, we may reasonably count on producing a solution of it, by the use of such substances as we have found produce the same evacuations or movement. Thus, fulness of the stomach we can relieve by emetics; diseases of the bowels, by purgatives; inflammatory cases, by bleeding; intermittents, by the Peruvian bark; syphilis, by mercury; watchfulness, by opium; &c. So far, I bow to the utility of medicine. It goes to the well-defined forms of disease, & happily, to those the most frequent.

Which doesn't mean I can't agree with him and cite him! For example, I wholeheartedly agree with the view he expressed to Dr. Wistar along the lines of skepticism affording a break from politics -- the latter being a "dry & dreary waste":

The natural course of the human mind is certainly from credulity to scepticism; and this is perhaps the most favorable apology I can make for venturing so far out of my depth, & to one too, to whom the strong as well as the weak points of this science are so familiar. But having stumbled on the subject in my way, I wished to give a confession of my faith to a friend; & the rather, as I had perhaps, at times, to him as well as others, expressed my scepticism in medicine, without defining it's extent or foundation. At any rate, it has permitted me, for a moment, to abstract myself from the dry & dreary waste of politics, into which I have been impressed by the times on which I happened, and to indulge in the rich fields of nature, where alone I should have served as a volunteer, if left to my natural inclinations & partialities.

Considering some of Jefferson's religious views, I can also understand the temptation in some quarters to edit the man out of the founding to the maximum extent possible. While it is beyond dispute that the man held religious views which don't fit a certain narrative of the founders which is being promulgated, I don't think the antipathy towards Jefferson is based so much on the views themselves as it is the fact that the founders had widely divergent religious views, and that this lack of consensus on matters of religion reflects a founding view of the First Amendment as keeping government and religion separate. Jefferson's advocacy of separation of church and state and his view of the First Amendment may well result from his involvement in religious arguments which were intractable in his time, and which still are, if this New York Times report about a textbook censorship board is true:

Even the course on world history did not escape the board's scalpel.

Cynthia Dunbar, a lawyer from Richmond who is a strict constitutionalist and thinks the nation was founded on Christian beliefs, managed to cut Thomas Jefferson from a list of figures whose writings inspired revolutions in the late 18th century and 19th century, replacing him with St. Thomas Aquinas, John Calvin and William Blackstone. (Jefferson is not well liked among conservatives on the board because he coined the term "separation between church and state.")
"The Enlightenment was not the only philosophy on which these revolutions were based," Ms. Dunbar said.

"I have long lamented with you the depreciation of law science. The opinion seems to be that Blackstone is to us what the Alcoran is to the Mahometans, that everything which is necessary is in him, and what is not in him is not necessary. I still lend my counsel and books to such young students as will fix themselves in the neighborhood. Coke's institutes and reports are their first, and Blackstone their last book, after an intermediate course of two or three years. It is nothing more than an elegant digest of what they will then have acquired from the real fountains of the law. Now men are born scholars, lawyers, doctors; in our day this was confined to poets.

In a letter from William Short to Thomas Jefferson dated July 2, 1822, Short makes it clear how he feels about the growing Presbyterian threat despite the positive growth of Unitarianism:

How does it happen that the Presbyterians are acquiring such influence in Virginia at the very time that they are losing it altogether in their former favorite region? At Boston the revolution in this respect seems to be complete. There is scarcely a man or woman there of information or fashion, who is not professedly unitarian. Even Cambridge has been taken complete possession of by this new school, who affirm however that they are oldest of the Christian sects, & that the idea of the trinity was an interpretation only after some centuries. The principal of Harvard University & all the Professors are unitarian. And from this source teachers of the doctrine are dispersed throughout the United States. You know without doubt, that the Chaplain, chosen last year by the house of representatives, is one of them. And such an instinctive terror of this new doctrine now exists amongst the other Christian sects, that they have all buried the hatchet hitherto raised against each other, & have become a band of brothers to combat this new enemy, the most dangerous probably they have ever had.

In Jefferson's reply to Short on October 19, 1822, he states that he considers Presbysterianism "the most intolerant and tyrannical of all our sects," and their clergy as "enemies." Still, he holds out hope that Unitarianism will come from the North!

Our enemies are in the vicinage of Wm & Mary to whom are added the Presbyterian clergy. This is rather the most numerous of our present sects, and the most ambitious, the most intolerant & tyrannical of all our sects, they wish to see no instruction of which they have not the exclusive direction. Their present aim is ascendancy by only their neat exclusive possession and establishment. They dread the light which this University is to shed on the public mind, and it's obstruction to their ambition. But there is a breese advancing from the North, which will put them down. Unitarianism has not yet reached us; but our citizens are ready to recieve reason from any quarter. The Unity of a supreme being is so much more inteligible than the triune arithmetic of the counterfeit Christians that it will kindle here like wild-fire. We want only eloquent preachers of the primitive doctrines to restore them to light, after the long night of darkness under which they have been hidden. Such would gather into their fold every man under the age of 40 female fanaticism might hold out a while longer.

In another letter to Short (dated April 13, 1820), Jefferson makes it clear what he thinks of Calvin:

The serious enemies are the priests of the different religious sects, to whose spells on the human mind it's improvement is ominous. Their pulpits are now resounding with denunciations against the appointment of Dr. Cooper whome they charge as a Monarchist in opposition to their tritheism. Hostile as these sects are in every other point, to one another, they unite in maintaining their mystical theology against those who believe there is one god only. The Presbyterian clergy are loudest. The most intolerant of all sects, the most tyrannical, and ambitious; ready at the word of the lawgiver, if such a word could be now obtained, to put the torch to the pile, and to rekindle in this virgin hemisphere, the flames in which their oracle Calvin consumed the poor Servetus, because he could not find in his Euclid the proposition which has demonstrated that three are one, and one is three, nor subscribe to that of Calvin that magistrates have a right to exterminate all heretics to Calvinistic creed. They pant to restablish by law that holy inquisition, which they can now only infuse into public opinion. We have most unwisely committed to the hierophant of our particular superstition, the direction of public opinion, that lord of the Universe. We have given them stated and privileged days to collect and catechise us, opportunities of delivering their oracles to the people in mass, and of moulding their minds as wax in the hollow of their hands. But, in despite of thier fulminations against endeavors to enlighten the general mind, to improve the reason of the people, and encourage them in the use of it, the liberality of this state will support this institution, and give fair play to the cultivation of reason. Can you ever find a more eligible occasion of visiting once more your native country, than that of accompanying Mr. Correa, and of seeing with him this beautiful and hopeful institution in ovo?

Thomas Jefferson and John Adams were bitter enemies, although both were Unitarians. In a long letter to Adams of August 22, 1813, Jefferson explains the need to keep secret his views of the Old versus the New Testament, and that his religious views derive from Joseph Priestley:

Very soon after my letter to Doctor Priestley, the subject being still in my mind I had leisure during an abstraction from business for a day or two, while on the road, to think a little more on it, and to sketch more fully than I had done to him, a syllabus of the matter which I thought should enter into the work. I wrote it to Doctor Rush, and there ended all my labor on the subject; himself and Doctor Priestley being the only two depositories of my secret. The fate of my letter to Priestley, after his death, was a warning to me on that of Doctor Rush; and at my request, his family were so kind as to quiet me by returning my original letter and syllabus. By this, you will be sensible how much interest I take in keeping myself clear of religious disputes before the public, and especially of seeing my syllabus disembowelled by the Aruspices of the modem Paganism. Yet I enclose it, to you with entire confidence, free to be perused by yourself and Mrs. Adams, but by no one else, and to be returned to me.

You are right in supposing, in one of yours, that I had not read much of Priestley's Predestination, his no-soul system, or his controversy with Horsley. But I have read his Corruptions of Christianity, and Early Opinions of Jesus, over and over again; and I rest on them, and on Middleton's writings, especially his letters from Rome, and to Waterland, as the basis of my own faith. These writings have never been answered, nor can be answered by quoting historical proofs, as they have done. For these facts, therefore, I cling to their learning, so much superior to my own.

George Washington was an Episcopalian, but he took a very tolerant view of other denominations, including Presbyterianism, Judaism, and Catholicism. His letter welcoming the Jews is well know, but he also stated that Catholics could be good citizens:

On March 15, according to The Maryland Journal and Baltimore Advertiser, a committee of Roman Catholics waited upon the President with a congratulatory address, to which the President replied. Washington said, in part:

"I feel, that my conduct in war and in peace has met with more general approbation than could reasonably have been expected: and I find myself disposed to consider that fortunate circumstance, in a great degree, resulting from the able support and extraordinary candor of my fellow-citizens of all denominations....

"...As mankind become more liberal, they will be more apt to allow, that all those, who conduct themselves as worthy members of the community are equally entitled to the protection of civil government. I ever to see America among the foremost nations in examples of justice and liberality. And I presume, that your fellow-citizens will not forget the patriotic part, which you took in the accomplishment of their revolution and the establishment of their government; or the important assistance, which they received from a nation in which the roman catholic religion is professed...may the members of your Society in America, animated alone by the pure spirit of christianity, and still conducting themselves as the faithful subjects of our free government, enjoy every temporal and spiritual felicity."

Dear Sir: I am informed that a Ship with Palatines is gone up to Baltimore, among whom are a number of Trademen. I am a good deal in want of a House Joiner and Bricklayer, (who really understand their profession) and you would do me a favor by purchasing one of each, for me. I would not confine you to Palatines. If they are good workmen, they may be of Asia, Africa, or Europe. They may be Mahometans, Jews or Christian of an Sect, or they may be Athiests. I would however prefer middle aged, to young men. and those who have good countenances and good characters on ship board, to others who have neither of these to recommend them, altho, after all, the proof of the pudding must be in the eating. I do not limit you to a price, but will pay the purchase money on demand. This request will be in force 'till complied with, or countermanded, because you may not succeed at this moment, and have favourable ones here after to do it in. My best respects, in which Mrs. Washington joins, are presented to Mrs. Tilghman and Mrs. Carroll. and I am etc.

On this same day (August 17) Washington received and answered an address from the master, wardens, and brethren of King David's Lodge of Masons in Newport. Both address and answer are entered in the "Letter Book." In the answer Washington said: "Being persuaded, that a just application of the principles, on which the masonic faternity is founded, must be promotive of private virtue and public prosperity. I shall always be happy to advance the interests of the society, and be considered by them a deserving brother."

On this same day (August 17) Washington also received and answered addresses from the Hebrew congregation of Newport, and from the clergy of Newport. In replying to the former he said: "It is now no more that toleration is spoken of, as if it was by the indulgence of one class of people, that another enjoyed the exercise of their inherent natural rights. For happily the government of the United States, which gives to bigotry no sanction, to persecution no assistance, requires only that they who live under its protection should demean themselves as good citizens, in giving it on all occasions their effectual support....May the children of the Stock of Abraham, who dwell in this land, continue to merit and enjoy the good will of the other inhabitants, while every one shall sit in safety under his own vine and fig-tree, and there shall be none to make him afraid."

I might be wrong, but where it comes to the religious views of others, Washington strikes me as being more personally tolerant (and less bigoted, if you will) than Jefferson. Yet unlike Jefferson, he seems to have given very little indication of what his personal religious views were. I suppose if you're an anti-Calivinist, you could cite Jefferson in support while pro-Calvinists could cite Washington's statements as being supportive of the Calvinists' contributions to the country.

These differences shed more light on the meaning of the First Amendment than they do on the respective merits of their positions.

There is much authority to be found in disagreement.

(Whether citing arguments between authorities is an argument to authority is a more complicated question.)