Tristram Hunt, a Labour education spokesman and historian, has attacked Education Secretary Michael Gove over his use of evidence.
It follows a Freedom of Information request showing Mr Gove's claim about children's lack of historical knowledge had been based on a UKTV Gold survey.
Mr Gove had been setting out the need to raise standards in history.
A Department for Education spokeswoman said: "There is plenty of other evidence to support this argument."
Mr Hunt, taking up last week's attack by the education secretary on the use of Mr Men characters in teaching history, accused Mr Gove of being "Mr Sloppy".
The dispute follows a newspaper article written earlier this year by Mr Gove in which he attacked opponents of his reforms and highlighted how much standards had been "dumbed down".
"Survey after survey has revealed disturbing historical ignorance, with one teenager in five believing Winston Churchill was a fictional character while 58% think Sherlock Holmes was real," wrote Mr Gove.
But the source of this claim was pursued in a Freedom of Information request which showed it was taken from a UKTV Gold survey from 2008.
Pressed for further evidence, the Department for Education pointed to surveys commissioned by Premier Inn, Lord Ashcroft, Professor Robert Tombs for think-tank Politeia, the Sea Cadets and London Mums Magazine.
Mr Hunt challenged the education secretary about the credibility of his claims.
"Before he rushes to judgement about young people, Michael Gove should make sure he has researched the evidence thoroughly."
Mary Bousted, general secretary of the ATL teachers' union, described the use of such surveys in shaping the education system as "ludicrous".
"It seems he will say anything to justify his ill-informed opinions. If he fails to properly evaluate his sources before he uses them he must expect to be ridiculed."
Proposed changes to the history curriculum have divided opinion and historians.
Supporters have argued in favour of ensuring that pupils learn a core body of knowledge in events, facts, dates and ideas.
There have been calls for a clearer sense of chronology to improve children's understanding of the sequence of historical eras and events.
Opponents have claimed the changes are over-prescriptive and promote a culturally narrow "kings and queens" view of history.
But there has also been hostility over how the message has been delivered.
Mr Gove's speech about the "infantilisation" of history has prompted an angry response from the Historical Association, which accused the education secretary of an "ill-researched attack".
But the Department for Education defended claims that "many children don't have a good grasp of historical facts".
As well as the range of surveys, a spokeswoman said: "There is plenty of other evidence to support this argument. A 2011 report by Ofsted found that many primary school pupils ended up with 'an episodic knowledge of history and their sense of time was unclear'."
"We are taking action to ensure all our children are given the first class education they deserve. Our approach to the history curriculum has been supported by some of the country's most eminent historians, including Prof David Abulafia, Prof Niall Ferguson, Dr David Starkey, Antony Beevor and Dr Amanda Foreman."