Donald Trump’s defenders and even some of his tepid critics on the Right seem determined to keep their moral blinders firmly affixed so as to narrow the discussion about the horrible incidents such as the mass murder at Tree of Life synagogue in Pittsburgh. In declaring Trump has “no responsibility” for the horrific murder, they feign or are actually guilty of severe moral and historical cluelessness.

No one I know thinks Trump is legally responsible for the deaths of 11 people or that he instructed anyone to commit violent acts. Aside from his remarks during the campaign to the Republican Jewish Coalition, he has steered far from anti-Semitic language — although the administration bizarrely left out “Jews” from its first Holocaust Remembrance Day statement and Trump said the neo-Nazis in Charlottesville included some “fine” people. Nevertheless, those denying any Trump responsibility surely know that is not the point.

If no politician’s words, written or spoken, have any effect on anyone, how does one explain hundreds of years of successful propaganda?

Politicians, aside from engaging the military or civilian law enforcement, have few tools other than their microphone. And certainly, those trying to skate by with a cramped definition of “responsibility” know this. We elect presidents in large part because they have the bully pulpit and can rally a country, put an issue front and centre, change minds and set the contours for acceptable debate. Few would argue that race-baiting leaders in the Jim Crow South had “no responsibility” for racial violence against African-Americans.

When politicians demonise outsiders — or insinuate their own countrymen are really outsiders — remove social inhibitions against expressing bigotry and dehumanise enemies, and those who they claim assist them, the hatemongers can hardly be surprised if some fraction of the population takes them seriously.

At the same time, we know from history and even contemporary examples how essential it is to rebut and discredit leaders preaching bigotry. We condemn loathsome xenophobia from Steve King, Republican representative from Iowa, or the font of anti-Semitic and anti-Israel drivel from Jeremy Corbyn, leader of the Labour Party in Britain, because we fear their noxious ideas will take hold and influence others to act.

The last people arguing that words don’t matter should be self-described conservatives. This is one reason why I find the “But Gorsuch” excuse for tolerating Trump’s rhetoric morally unsound; of all the things he does, the vile statements he repeats at virtually every public appearance may have the most long-lasting effect on his followers. They have spent decades declaring that politicians’ words influence culture, family structure, crime and just about everything else. It is bizarre to argue that they have no influence on the most impressionable and least stable people among us.

Trump has eradicated red lines of civility, refused to condemn neo-Nazis and offered a steady diet of grotesque stereotypes of immigrants. He has demonised the media and raised fear of foreign terrorists embedded among refugees. His campaign and now his presidency fan the flames of white grievance; he has done more to mainstream nonfactual conspiracies than any president. To say he bears no moral or political responsibility when disturbed or fringe characters hear him, take him seriously, extrapolate from his remarks and engage in horrible acts is wilful blindness. He is not solely responsible. He is not mainly responsible. But the guy with the biggest megaphone on the planet is partly responsible when unbalanced people are inspired by his toxic rhetoric and that of followers whom he refuses to repudiate.

The uptick in racial violence, anti-Semitic acts and hateful rhetoric that have become omnipresent in the Trump years did not arise out of thin air. And for now, I’ll leave the absolute refusal to address any reasonable gun laws out of it; but in that, the National Rifle Association and its obedient minions are hardly blameless. We must all be more specific in identifying names of those who share responsibility for the toxic fumes that violent, unstable people inhale. So here goes.

Rupert Murdoch, the executives, on-air talent and shareholders of Fox need to self-reflect. Fox is home to anti-immigrant cranks such as Lou Dobbs and Laura Ingraham. It is where the caravan is attributed to Jewish billionaire George Soros, where Sean Hannity leads his audience to believe immigrants are especially prone to commit crimes and where Tucker Carlson has adopted the language of white nationalism, decrying diversity in America. Unless and until Fox cleans up its act — drop conspiracies made up out of whole cloth, end demonisation and hysteria about immigrants, and stop invoking Soros to explain every political threat, real or imagined — people of good will should not appear on Fox News, advertise on it or watch it.

Instagram and Twitter deserve blame as well. These companies must be much more aggressive in blocking and taking down anti-Semitic, racist and bullying messages and images. There should be zero tolerance for those who traffic in detestable material. Surely algorithms exist to detect the lion’s share of racist and anti-Semitic material — and if not, these hugely successful companies need to hire an army of people to review what’s out there on their platform. Once detected, the material must be removed in a timely fashion and those who post it banned — for life. I’m not calling for a law; I’m calling for those who share responsibility for the pollution of our politics to act responsibly, as if they actually care about the country that allowed them to make billions.

Moving on, House Speaker Paul Ryan and other Republicans should throw King out of the GOP caucus. He spews anti-immigrant venom and appears with Austrian neo-Nazis. Members can vote to expel him from the House, come to think of it, for conduct unbecoming a congressman. Iowa voters should have voted him out long ago. Their responsibility — voters and GOP leadership — is to remove toxic leaders from positions of power where they can influence others. The greatest moral failure of Ryan’s career will be his spinelessness in the face of insane conspiracies and hateful speech. “I haven’t seen” the tweet, he said. In silence, he gave cover to Trump for non-stop lying and detestable language.

Republican politicians including Trump and Majority Leader Kevin McCarthy, and right-wing publications and websites must cease using Soros, an anti-Semitic bogeyman, to rile up their base. For an excellent takedown of the Right’s Soros-obsession, read Kevin D. Williamson on the topic on nationalreview.com. The GOP and the President should denounce, not celebrate “nationalism” — as that term is now understood. Enough hyping the caravan, which is dwindling and hundreds of miles away, from the White House, on Fox, on right-wing websites and, yes, in the mainstream media. It’s not a threat to America, let alone an immediate threat. And while they have largely stopped doing it, cable TV should not be carrying Trump’s bile-filled campaign speeches live. They can report after the fact on his remarks, pointing out where they depart from reality.

In sum, we all have a tendency to talk about “hate” or “bigotry” as if such sentiments were inanimate objects. We have to root it out. We have to combat it. But there is no “it” — there are people who say, write and do hateful things. And they should be held accountable. Let’s end the lazy thinking and the moral denseness. Lots of people have behaved in ways that degrade our culture and give oxygen and inspiration to dangerous people. We should call them out — by name — and implore them to do better.

• Jennifer Rubin writes reported opinion from a centre-right perspective for The Washington Post