S yllogisms have a consistent structure. For example, All books printed by Gutenberg are valuable . These books were printed by Gutenberg . Therefore, these books are valuable . For example, All languages used by humans are expressive.
Human expression is important.
Therefore, all languages are important. For example, John will surely fail his calculus exam, because he hasn't studied. That example though illustrates some of the interesting differences between the syllogism and the enthymeme. Whereas the syllogism produces a valid conclusion from the truth of its premises, the enthymeme gives us only tentative conclusions based on probable premises. In the example above, for instance, it is probably true that John will fail, but it is not certain.