In today's world of economic inequality and misinformation, misleading partial information, and outright lies spread around the internet, the truth - the "whole" truth - has become a scarce and valuable commodity.
Demagogues subvert the truth and US President Donald Trump and his followers assert their right to invent and disseminate "alternative facts".
In their quest for power, these demagogues have taken to attacking expertise, intellectual rigour and science.
They attack the respected institutions and processes that serve society by helping to distinguish between what is and is not true - climate science, the judiciary, academia and journalism.
It is important to remember the motives of the demagogues: they want power and profit and will attack whatever or whoever gets in their way.
In this context we are proud to be attending the Global Investigative Journalism Network conference at the University of the Witwatersrand this week, and proud, too, that we will launch African Muckraking: 50 years of African Investigative Journalism, the first collection of African investigative journalism from around the continent written by Africans.
Inspired by investigative reporter and professor Anton Harber, the book was edited by Anya Schiffrin and Ugandan media development expert George Lugalambi. It goes back 50 years to include African reporting on corruption, women's issues, human rights, oil, mining and other subjects.
The expression "muckraking" comes from a speech made by US president Theodore Roosevelt and refers to the 17th century Christian allegory A Pilgrim's Progress by John Bunyan.
The hope was that by exposing (raking) the muck (the slimy activities engaged in by businesses and governments), societal outrage would lead to change. US muckrakers did succeed in bringing about change, in the way that Upton Sinclair's exposure of the filthy practices of the US's meat-packing industry led to new food health and safety standards.
Investigative journalists have played a critical role in helping to keep governments and corporations accountable and in exposing wrongdoing - not just by government but also by big business. The book describes some important investigative work on pollution in Nigeria, blood diamonds in Angola, corruption and banking scandals in Cameroon and Uganda, and mistreatment of women in Liberia and Tunisia.
Many of the big moments in African history are chronicled in its pages: Chinua Achebe's comments on the Biafran war in Nigeria; Salim Amin's loving essay about his father, the legendary cameraman and photographer Mo Amin; as well as gems such as Rodney Sieh's introduction of his gadfly great uncle whose writings exposed corruption in Liberia.
One of the most powerful parts of the book is Sheila Kawamara's 1994 coverage of the Rwandan genocide that was published in the New Vision.
Kawamara's story is a reminder of the bravery exhibited by many of the journalists, particularly reporters who exposed corruption and police or military brutality.
Henry Nxumalo, who lived in apartheid South Africa and wrote for Drum magazine, got himself arrested so that he could write about prison conditions. Carlos Cardoso wrote about corruption in the Mozambican government, died under mysterious circumstances and is now rightly considered a national hero.
Rafael Marques has paid the high price of time in prison for writing about blood diamonds in Angola.
The list goes on.
These essays illustrate the dangers confronting those committed to investigative journalism. Getting the story is hard - many of the journalists in this volume took great risks; they believed that it was worth doing so.
They knew that the role of journalism is not just to promote government policies. Indeed, Africa can't have sustainable, democratic, equitable development without the kind of accountability that only investigative journalism provides.
This volume illustrates the best of this investigative journalism over the past century, but its real intent is to inspire and celebrate the continuation of this tradition.
Throughout Africa, investigative journalists put their lives on the line to get their stories out.
According to the Committee to Protect Journalists, 32 journalists have been killed so far this year and 1260 have been killed since 1992. CPJ executive director Joel Simon explains why this is so in his important book, The New Censorship: Inside the Global Battle for Media Freedom.
The situation on the continent varies. Journalists are being killed by extremists in Nigeria and jailed in Egypt, and the governments of Eritrea and Ethiopia are highly repressive. Journalists are feeling pressure from business and government in many countries, including South Africa, but many countries, including Ghana and Nigeria and Kenya, can boast of a wide range of titles as well as radio and online news.
Africa's media landscape is as diverse as the continent is. At the conference at Wits this week, we will listen intently as some of the world's best journalists share new techniques with their colleagues and compare notes on stories that still need to be told.
Because investigative journalism holds governments' feet to the fire, they often feel uncomfortable with it, and try to stifle it.
They should feel uncomfortable; investigative journalism that doesn't make people uncomfortable is not doing its job.
But for a democratic society to thrive, investigative journalism is essential. Without the media "raking the muck", Africa - indeed the whole world - will be worse off.
• Schiffrin runs the media and communications programme at Columbia University's School of International and Public Affairs. Stiglitz is University Professor at Columbia University and received the Nobel prize in 2001 for his work on the economics of information..