Posts Tagged ‘ philosophy ’

2. Hidden premises

Often, premises are implicit or hidden in an argument. This means they are not mentioned but are assumed – either knowingly or unknowingly – by the speaker or writer. Reconsider example 5 from the previous post:

5. Life on Earth is in deadly peril. If we had not burnt so much fossil fuel in the late 20th century, there would not have been so much carbon dioxide in the atmosphere. If there were less carbon dioxide in the atmosphere, the greenhouse effect would not be running out of control.

In fact, this argument only works if we assume the truth of another premise, namely, that ‘When the greenhouse effect runs out of control, life on earth is in deadly peril’. Often, hidden or implicit premises like these are not mentioned simply because they are obvious.
Here’s another argument with an implicit premise:

6. H2O is abundant on Earth. 70% of the world’s surface area is water.

The implicit premise is that H2O and water are the same thing, but why mention something in an argument which no one finds controversial? It would be tiresome to have to mention everything presupposed by an argument’s conclusion when most of it is not in dispute. That being said, however, it is essential that the philosophy student realises that hidden premises are particularly important precisely because in complex arguments on controversial issues, there are often implicit premises that may not be recognised by one or more parties. What is more, it is these that often turn out to be the very premises which are responsible for the controversy. Here is a good example:

7. Murder is always wrong. Even though the state sanctions capital punishment, clearly capital punishment is wrong.

The claim in this argument cannot be established unless one agrees to the hidden premise that ‘capital punishment is murder’. Whether one agrees with the argument’s claim that ‘capital punishment is wrong’ will turn precisely on this hidden – and controversial – premise rather than on the two uncontroversial stated ones.

If you think carefully about any argument, you will almost always find a hidden premise. This is because speakers and writers usually have a common background with their audience, so that some information is unnecessary to mention. However, you should always think about hidden premises and weigh up whether they are significant or not. The argument in 7. has many implicit premises including, for example, ‘the State has the power to punish people’. However, this is not significant because it is irrelevant to establishing the claim – it makes no difference to the argument one way or the other.

REVIEW
• All philosophically-interesting arguments contain hidden premises
• Hidden premises need to be recognized and assessed as to their significance

Try Exercise 2 to test your understanding of this post, or continue reading

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