Counter Arguments

• An argument is essentially one sided• But it can be important to deal with opposing

views or anticipated counter arguments• We need to recognise when a counter

argument is being used as a premise and differentiate this from the actual conclusion

• While some may argue that we should cull poultry in Scotland because a swan has died of bird flu, this view is an overreaction. A single death is not yet an epidemic. Nor can bird flu be transmitted from human to human. A wholesale cull of birds would have consequences far worse than the virus itself. More measured precautions should be taken to prevent the spread of bird flu.

• University education should be available only to the academic elite. Some may argue that education is a right for all, but these are largely unintelligent, ignorant young people clamouring about their rights to everything. Education is vital to the economy, they cry, but a detailed knowledge of medieval German poetry is of no use to anyone.

Counter Examples

• Some times we find it difficult to assess the arguments because we get distracted by the content and our prior knowledge.

• This can prevent us from focusing on the validity of the argument’s structure.

• One way to avoid this is to find another argument with the same form as the one under consideration.

Intuitively convincing but invalid structure

• All birds have feathers• An eagle has feathers• Therefore, an eagle is a bird

Intuitively unconvincing but valid structure

• If it is raining then we’re in Scotland

• We aren’t in Scotland• Therefore, it isn’t raining

Same form different content

Original• All birds have feathers• An eagle has feathers• Therefore, an eagle is a bird

• If it is raining then we’re in Scotland

• We aren’t in Scotland• Therefore, it isn’t raining

Counter Example• All dogs have eyes• A human being has eyes• Therefore, a human being is a

dog

• If you are a dog then you are a mammal

• A lizard is not a mammal• Therefore, a lizard is not a dog

Test the validity of these with counter examples

• All politicians are liars• Mr Jones is a politician• So, Mr Jones is a liar

• All sea captains are sailors

• Bert is a sailor• So, Bert is a sea captain