Stephen’s Guide to the Logical Fallacies – by Stephen Downes. Very interesting site with the fallacies definitions, examples and a way to proof the fallacies.
In an analogy, two objects (or events), A and B are shown to be similar. Then it is argued that since A has property P, so also B must have property P. An analogy fails when the two objects, A and B, are different in a way which affects whether they both have property P.
Example: Employees are like nails. Just as nails must be hit in the head in order to make them work, so must employees.