How to Win Every Argument: The Use and Abuse of Logic (2006)

Illicit process 97

whether others should be banned from doing things you do not
approve of.

Jogging in public should be banned. There are studies which show it can

increase the risks to health, rather than decrease them.

(Even if it were true, would it be an argument for banning public

jogging? It sounds as though the major adverse effect is not on the

jogger's health, but the speaker's conscience.)

Illicit process

There is a rule about arguments which tells us that if a term in the
conclusion refers to the whole of its class, then the evidence
pointing to that conclusion must also have told us about the
whole class. We cannot reach a conclusion about 'all estate
agents', for example, unless we start with some knowledge
which applies to all of them. To know that some estate agents
are guilty of this or that practice will not justify us reaching
conclusions about all of them. Arguments which break this rule
are said to commit the fallacy of illicit process.

All tax-collectors are civil servants, and all tax-collectors are bullies, so all

civil servants are bullies.

(Too harsh. There may be some somewhere who are just a little

overbearing. The fallacy is that we refer to all civil servants in the

conclusion, but the premise only tells us that tax-collectors are some

of them.)

The argument which uses illicit process has to be fallacious

because it makes unsupported claims. Although the premises

talk only about some of a class, the conclusion introduces for the

first time the rest of that class. In other words, we try to reach