http://changingminds.org/disciplines/argument/fallacies/false_analogy.htmDescription
X has property Y. Z is like X. Z therefore has property Y.
Use analogical comparisons to connect the item in question to another item that has desired characteristics. You can then claim that the first item has the desired property.
Example
People are like dogs. They respond best to clear discipline.
This soap is like a dream. It lifts you up to a spiritual plane.
A school is not so different from a business. It needs a clear competitive strategy that will lead to profitable growth.
Discussion
Analogy is saying 'A is like B' and is a powerful way of explaining one thing in terms of another. Where it falls down is when A is assumed to be like B in all respects and any attribute or characteristic of B can be unequivocally attributed to A.
In the false metaphor variant, the comparison is metaphoric. As analogies say 'A is like B', metaphors say 'A is B'.
Analogy: She is like a dog
Metaphor: She is a dog
The effect is still the same: the attributes of the analogy or metaphor are brought back to the original subject. The major difference is that in a metaphor, the equation is more explicit and direct.
The typical fallacy in this is that the comparison is not a good one and creates significant falsehood.
Classification
Analogy, Inductive, Falsehood
Also known as
False Metaphor
See also
Analogy, Metaphor