Regarding the power and science of lies in politics

The power

There is significant political power in lying to the public. That is especially true for a public that is polarized with a significant number of people conditioned to accepting or excusing lies from the leaders they support and are loyal to. The old adage, "Meh, all politicians lie. It's no big deal", is not only a democracy killer, it's also a tyranny builder. Tyrants and kleptocrats in a lies-accepting society love lies. They use them ruthlessly, fact-checkers be damned. Not lying to a lies-conditioned public wastes political power.

From a moral philosophy point of view, the power of lies and deceit in a democracy is that the liars and deceivers take from deceived people their power to think, choose and act on the basis of facts and truths. In short, lying and deceit are inherently anti-democratic and pro-tyranny, and rather powerful. 

The science

A Raw Story article, 'That is not true': Trump hit with blunt fact check after spreading Supreme Court lie, exemplifies how a major source of power for Trump and MAGA elites works in practice. First a liar tells their lie, or an ignorant person tells a falsehood. Then fact checkers check and expose the lie/falsehood as false. In partisan politics, the net effect of fact checking on the public is modest at most. Many hard core Trump supporters will reject the fact-checkers as liars or idiots, or accept Trump's lie as just Trump speaking his mind being "honest", no big deal.

The Raw Story article reports that Trump falsely claimed the Supreme Court endorsed his policies. That was immediately contradicted by legal experts and factual records showing no such ruling(s) exists or says what he claims. It was an easily debunked lie, plain and simple.

Experiments where people were exposed to Trump's lies and then corrections show that both Democrats and Republicans generally reduce their belief in the specific falsehood after a fact check, including some Trump supporters. But his lie is likely to do more to reinforce and spread misperceptions than the fact check does to correct them among Trump’s core supporters. Research indicates that the fact check mainly limits damage among non-supporters and the less engaged. For strong Trump supporters, research shows they are more likely to accept Trump's false claims because they come from him. For some supporters, even when they know they are being lied to, Trump's lies are treated as as credible "facts". That is a manifestation of partisan moral flexibility. In general, Trump's lies increase false beliefs and reduce trust in institutions he targets such as courts, news media, Democrats, elections, etc. 

Among Trump skeptics, fact-checks tend to work as intended. That increases their confidence in democratic processes and slightly reduces support for anti-democratic actions and policies. Among committed Trump partisans, corrections generally have limited effect because of motivated reasoning. They ignore or dismiss the fact check, and in some cases double down on the original claim or shift to narratives about "biased media" or a "weaponized" judiciary.

At the aggregate level, a single lie plus a single fact check probably produces an entrenchment or slight radicalization of Trump's base, and (a) a modest corrective effect among non-supporters, and (b) a small net increase in polarization and institutional mistrust. Trump's lies generally help him more than it hurts. So why not lie?

The danger to democracy and the rule of law is cumulative. Repeated, uncorrected or partially corrected lies about the Supreme Court and other institutions gradually normalize the idea that legal reality is whatever a lying leader says it is. Over time anti-democracy lies meaningfully weakens overall public acceptance of rule-of-law limits and even support for democracy and the civil liberties the liar targets, e.g., abortion, voting rights, inconvenient free speech, etc.

Q: Given the gravity of Trump's and elite MAGA's threats to democracy, the rule of law, civil liberties and the public interest, is it morally justifiable for political opposition and elite Democrats to resort to constant lying just like Trump and MAGA elites?