Statements invoking "the people" are generally no more than political demagoguery from those who claim to represent this magical and rousing entity.
I don't know to what extent Poles helped the Nazis carry out the Holocaust, but it is impossible that it involved 100% of the Poles. It is also inconceivable that it was 0%. Moreover, since I don't speak Polish, I haven't read the law that was just adopted in that country. Despite these caveats, I think there are still a couple of lessons to be safely drawn from the current controversy.
According to an interesting story in the Wall Street Journal of February 2, Polish president Andrzej Duda approved a libel law, which includes jail penalties, against "accusing the Polish people of assisting in the Holocaust." It would be important to know which exact expression the Polish President and others used. The Wall Street Journal reporter also writes "the Polish population" and "Polish society," not in quotation marks. Translation is a complex matter but the concept of "the people" has been around for a few centuries--not to mention more ambiguous concepts in antiquity, such as the Roman senatus populusque romanus ("the senate and the people of Rome"). But it wouldn't be surprising if Duda invoked "the people" as modern politicians, especially the populist ones, love to do.
The first lesson is that the expression "the people" is meaningless or fraudulent. It is fraudulent if it is meant to convey the idea that it regroups 100% of the Poles. A fundamental discovery of economics in the 20th century was that there is no way to aggregate the preferences of all individuals into a single set of non-contradictory preferences (as if "the people" were a super-individual comprised of all flesh-and-blood homunculi). More precisely, such an aggregation is impossible if we don't arbitrarily constrain individual preferences and ignore diversity among individuals. "The people" thus means a proportion of the population smaller than 100% - and, in practice, usually much smaller than 100%. "The people" refers to a portion of all the people, a portion typically made of those who impose their preferences or views on the others. This is the essence of Kenneth Arrow's Impossibility Theorem. I discussed it along with some related theories in my Econlib article "The Vacuity of the Political We."
Since "the people" is only part of the people, it is not surprising that some Poles--more than 0%--would have helped the occupying Nazis in their persecution and slaughtering of the Jews. The extent of this assistance, we are told, is a controversial issue among scholars. Unless one defines what one means by "the people"--which part of a society one is talking about--it makes no sense to say that the Polish people assisted or did not assist in the Holocaust. Statements invoking "the people" are generally no more than political demagoguery from those who claim to represent this magical and rousing entity.
Only once this understood, we may ask sensible questions, such as which parts of Polish society--which subsets of individuals--cooperated or did not cooperate in carrying out the Holocaust.
A second lesson, of course, relates to the importance of free speech. Duda's claim that nobody should be "accusing the Polish people of assisting in the Holocaust" is incompatible with free speech. "We have a right to our historical truth," he also declared, as if nobody is at liberty to challenge the truth he believes in. (The "our" of course does not change anything, as it refers to a vacuous political "we".)
We can never be sure that the opinion we are endeavoring to stifle is a false opinion ... Those who desire to suppress it, of course deny its truth; but they are not infallible. They have no authority to decide the question for all mankind, and exclude every other person from the means of judging. To refuse a hearing to an opinion, because they are sure that it is false, is to assume that their certainty is the same thing as absolute certainty. All silencing of discussion is an assumption of infallibility.
Mill saw that there is more to the topic than this philosophical argument. There is an economic argument: we cannot presume something to be true if it has not survived the test of competition. Mill explained:
There is the greatest difference between presuming an opinion to be true, because, with every opportunity for contesting it, it has not been refuted, and assuming its truth for the purpose of not permitting its refutation. Complete liberty of contradicting and disproving our opinion, is the very condition which justifies us in assuming its truth for purposes of action; and on no other terms can a being with human faculties have any rational assurance of being right.
Imagine what would happen after decades of repressing the hypothesis that many Poles assisted the Nazis, or (to take another example) that the Holocaust did not happen. There would be no reason to believe what would by then be conventional wisdom.
Another economic argument for free speech is that Leviathan will certainly use a partial prohibition to increase its power and further the interests of the courtiers and cronies whose support he needs. Leviathan acts this way because such are the incentives of many individuals in the ruling gang.
Besides the meaning (or lack thereof) of "the people" and besides the arguments for free speech, a third lesson relates to nationalism. "It is not about Jews," a Warsaw think-tanker is reported to have said, "it's about sovereignty." When announcing his approval of the new law, the Polish president was "standing before five Polish flags," notes the Wall Street Journal. The picture in the newspaper actually shows six flags, but the symbolism of flag proliferation, not their exact number, is what matters. The symbolism lies in the glorification of nationalism, which brings grist to the mill of state power. Rulers and rulers-to-be love nationalism and flags for a simple reason: they are means to increased power.