On Credibility of Sources – notes for a tutorial

1. Is there any source (written by a human) that we can trust absolutely?

Answer is no, or at least we can’t be sure. I say ‘by humans’ because for some people a god may have written a text which is absolutely true. Avoiding getting into that.

2. What’s the problem with not trusting any source?

We can be very clever and say ahhh I don’t trust anything I read or hear, but this is about as useful as trusting everything we read or hear. If we don’t trust anything at all to any extent we are reduced to what we can verify personally, which is very limiting.

The alternative is to apply a set of rules or general questions to try to work out how reliable or credible or trustworthy a source is, in a relative way, while recognising nothing is absolutely certain.

3. What reasons are there to trust a source?

Expertise, experience, qualifications. Desire to tell the truth, to give people information, to help people. Commitment to truth for its own sake – to saying something true. Or commitment to being seen as trusted.

 4. What reasons are there to not to trust a source?

Two main answers:  it might be wrong, the author (or publisher) might be lying.  Questions as to why someone might be wrong or lying – or not telling the whole truth, or spinning something – can be further investigated. One way to look at this is to consider what the author or publisher might have to gain by stating something is true when it is not, or when it is uncertain.  In general, the more there is an advantage for the author in stating the truth of something, the less reliable the source.  This is the case even if the source is entirely truthful and trustworthy: that there is a reason not to tell the truth compromises the source, whether the truth is being told or not.

Criteria for critiquing a source

None of the following questions give an absolute ‘tick’ or ‘cross’ to a source. Just because there might be a reason to trust or not trust a source doesn’t mean we can decide absolutely whether it is credible or not. If we ask all of the questions below in the context of a particular source we should come up with some reasons to trust that source, and some reasons not to.

In general, the more reasons there are to trust a source, without reasons against, the more reliable it is. The more reasons there are not to trust a source the less reliable it is.  Since we can’t be sure about the reliability of a source, we have to trust our set of criteria.  Even if a source happens to be very truthful, its reliability is reduced if it fails the test on some of the points below.


1. Who authored the document, and what institutions are its author/s or publishers associated with? Why did the author write the document? What authority does the author have on the subject (how much do they know?)  Why might the author be wrong? Why might the author not tell the whole truth? (Conversely, is there an advantage for the author in being honest?)

2. Who funded the writing or publication of the document? Why? Does the person or organisation that funded the publication of the document an interest in presenting wrong information, or not telling the whole truth? (conversely, is there an advantage for the publisher or source of funding in being honest?)

3. Is there a ‘bias’ (a lean, favouring of one side?) Is the tone of the writing measured, or passionate and opinionated? Are there elements of opinion – statements of value without reason? Are any conclusions balanced? Is more than one side of an argument considered – is it a ‘dialectic; or a ‘rhetorical’ argument?

3. Has an editorial or peer-review process been applied – has the information been checked?

4. How current is the document – when was it published, how recently updated?

5. Does the document list or link to its sources – hyperlinking, a bibliography, in-text referencing?

6. Is the spelling or grammar correct? Is the document well-written? Or beautifully written?


Consider the questions above with respect the following kinds of sources:

something a friend says

an academic journal article or scientific paper

a text book

a newspaper article or

TV news

an advertisement

a website from a non-government organisation

a tweet

a document from the government

A speech by a politician

a blog

A TV documentary

A novel (a fictional story)

A poem