Chapter 7
Is Ought Fallacy
Many people fall for the ‘is-ought’ fallacy in all sorts of arguments. Therefore take care when arguing about animal rights because you may be making an error.
An 'is' is a description of a fact, for instance humans evolved from animals. An 'ought' is a value judgement, that something ought (or should) be done, for instance you ought to be nice to animals. The is-ought fallacy says that facts have no bearing on value judgements. Facts are facts whereas value judgements are value judgements, and it is a fallacy to argue from the one to the other.
We cannot incontestably state what we should do based on facts alone.
Thus, it is a fallacy to conclude that because humans evolved from animals so people should be considerate to animals.
Philosophers give credit to the Scottish philosopher David Hume (1711 - 1776) for bringing this fallacy to light, often encapsulated in the saying: "you cannot derive
ought from
is".
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David Hume. He could not derive ought from is. |
Here are three examples of trying to derive an ‘ought’ from an ‘is’.
- 'Among all animals, humans excel at reasoning (fact); therefore humans ought to have special treatment (value judgement).' Simply by being good at reasoning does not mean humans should have preference over other animals.
- 'People have always eaten animals (fact); therefore, vegetarianism is wrong and you should eat meat (value judgement).' That our ancestors ate animals does not mean we cannot exercise a moral choice on whether or not we should eat animals.
- 'According to the theory of natural selection well adapted species survive and species not well adapted go extinct (fact); therefore we should not try to conserve species because only the best species will then survive (value judgement).' Although species go extinct it does not mean we should ignore their plight, especially if we are responsible for driving them to extinction in the first place.
'Is' statements are claims about what there is (for instance people kill 40 billion chickens every year). 'Ought' statements are claims about what people should do (for example people should stop killing chickens). The consideration of facts can guide our behaviour about what action we should take, but no fact can inevitably determine what we should do.
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