World of Wonders

When we see things that aren’t, we miss the wonderful things that are.

Twitter and the Convergence of Evidence in Iran

A friend recently wrote on his blog about his concern for the many tweeters he was following in Iran in the wake of that country’s contested election. A reply was posted in response that included this statement: “Who is to say that half the people you are following are even real people–and not a 30-year-old jackass getting kicks out of how many people are following him?” Here’s my reply to that post:

It’s true you can’t be sure that any individual tweet is authentic. And we should be sceptical; we should always exercise media literacy, whether we’re reading tweets, the Huffington Post, a hard-copy of the New York Times, or we’re listening to CBC radio, or watching BBC World News. In fact, it is entirely reasonable to believe that some percentage of tweets are fake.

But, if your conjecture is that a significant number are fake and that they are painting a misleading picture, then at a certain point, the onus is on you to offer both an explanation of why this is happening and proof that it is. Not only that, but we also have to consider this.

If our knowledge of what’s going on in Iran were limited to Twitter alone, we would be right to be very sceptical of every and all tweets and the overall picture they are painting. But Twitter isn’t our sole source of information. There are reports coming to us from other sources, such as traditional news agencies (albeit restricted), individuals in contact with their friends and families in Iran, etc. There is also our general knowledge of the political situation in that country.

The consistency of these news reports, personal accounts, historical knowledge, and tweets is what is referred to in science as a “convergence of evidence.” And when independent lines of evidence converge on a single conclusion, that is strong evidence for the conclusion.

For e.g. we know Darwin was right–not because of any single piece of data–but because of the overwhelming convergence of evidence from many different sources: geology, paleontology, genetics, zoology, etc.

And, despite attempts to deny the fact of the Holocaust by disproving discrete or isolated claims about it, we know it happened because of the overwhelming convergence of evidence from written documents, eyewitness accounts, photographs, the camps themselves and inferential evidence. (For more on this, read Michael Shermer and Alex Grobman’s excellent Denying History.)

Not only that, but the internal consistency of large numbers of tweets makes them all the more convincing.

So, while we may not be able to say that any single tweet is authentic, as a whole they contribute to our understanding of what is going on halfway around the world. It is a compelling, disturbing situation that we should all be following, with every means possible.


Filed under: media, politics, science literacy, , ,

About me

I am a Toronto-based writer, author and photographer who is inspired and fascinated by science. Science is our best way of understanding the natural world, but it is much more than that. Science is culture, and its pursuit ultimately leads to meaning, values and wonder.  My interests include evolution, Darwin, the Galapagos Islands, secular humanism, religion, skepticism, climate change, and science culture.  For many years, I wrote and produced astronomy programs for the McLaughlin Planetarium of the Royal Ontario Museum. I am author of many books for young readers (Sterling Publishing and Penguin Young Readers, N.Y.) and articles for children's magazines. I also write non-fiction related to the themes reflected in this blog. You can read some of my longer non-fiction and view my photographs at, and follow me at


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