A great online Critical Thinking quiz…

Critical thinking quizzes are usually rubbish. In fact in some countries even the material provided by exam boards are rubbish. And I’m saying this not without sympathy. One only needs to watch a single episode of Family Guy, The Revolution will be Televised or Brasseye to be reminded that though errors in reasoning can be hilarious, they are not always clearly a clear case of one error. Of course occasionally they are (“it’s not a drug it’s a drink” etc), but more often one could make a case that a number of mistakes have been made (eg. Peter Griffon’s incredible ‘Mark Harmon’ speech).

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Routledge’s companion website for Tracy Bowell and Gary Kemp’s Critical Thinking: A Concise Guide is not like this. It is clear. It is constructive and it is helpful. I haven’t yet managed to read my inspection copy, but if it is as clear as this site I will be adopting it right away. You can find it here: Critical Thinking: A Concise Guide.

Also remember I have my basic introduction called Errors In Reasoning here.The best bit is that I have added a blog of real life (and usually funny) errors that you can use to test yourself.

John Nolt on Moral Arguments

For those of you studying IB Philosophy, or taking Higher but interested in going beyond the simplicities of the course, John Nolt’s Environmental Ethics for the Long Term has an excellent section on philosophical arguments in ethics.

Section 2.2.1 has one of the best explanations of the “is/ought” fallacy I have ever read. Using the terms ‘prescriptive’ and ‘descriptive’ to refer to premises that respectively contain or do not contain a sentiment of something being right or wrong, he uses the phrase ‘prescriptive reasoning’ to refer to an argument where (at least) one premise and the conclusion include some sort of moral valuing.

Of course an argument can be valid and sound if it contains no moral sentiments (1), and one which has ‘moral’ or ‘ought’ premises might lead to a valid and ‘ought’ type conclusion (2).

Example 1:

all volvo cars have a steering wheel

my car is a volvo

therefore my car has a steering wheel

Example 2:

one should intervene when one person is abusing another against the latter’s will

‘abusing another against their will’ is what happens in sex-trafficking

therefore you should be acting against sex-trafficking

Of course one might object to the ‘truth’ of each of the premises here, but if one did agree with both then it would commit you to the conclusion. This is an example of what Nolt calls ‘prescriptive reasoning’. The problem is when someone tries to move from purely ‘descriptive’ premises to a prescriptive conclusion. This is the is/ought fallacy. The example used by Nolt is the use of Social Darwinism by the Nazis, simply because the ‘strong’ or ‘fittest’ survive it certainly does not follow that one should act in a way to make this happen.

Allowing this ‘prescriptive reasoning’ to stand is not the same as believing it to be sound. In fact it can be particularly difficult to spot problematic premises. Consider the following:

We ought to eliminate suffering.

The only feasible way to eliminate suffering is to eliminate all sentient beings.

Therefore we ought to eliminate all sentient beings.*

*Nolt, J Environmental Ethics for the Long Term (Abingdon: Routledge, 2015) 39.

The Revolution Will Be Televised

Great for testing your critical thinking skills:

So It’s a well known fact that if we got rid of the Queen, within a couple of years we’d be a communist state led by anarchists led by Ken Livingston.

Look at the French, they got rid of the Monarchy and they’re a bunch of Ar***oles. Do we want to be like the French?


We’ve got not not actual evidence that she is a witch, but then again we have no actual evidence that she is not a witch.

If you ask yourself why has The Sun witch-hunts against paedophiles, Muslims and Gypsies but never against actual witches? conspiracy theory?