The Non Sequitur Fallacy

1).  All humans are mortal.
2).  Socrates is a human.
3).  Therefore dragons exist.


I hope that most people, upon even just a cursory examination of the above syllogism, could easily spot the major problem with it.  The existence of dragons does not in any way follow from humans being mortal and Socrates being a human!  The logically-valid conclusion, meaning the conclusion that actually follows from the premises (just because a conclusion follows from premises doesn't mean the premises are true, though), is that Socrates is mortal, not that dragons exist.

The syllogism is plagued by the non sequitur fallacy, with non sequitur meaning "it does not follow".  Whenever someone affirms a conclusion that has nothing to do with the preceding points--like "if Donald Trump is narcissistic then he must be an extraterrestrial"--they have succumbed to this fallacy.  Non sequiturs like this are not always spotted so quickly by people, though, as many people use non sequiturs without ever realizing they are doing so.  Many fallacies, although they go by different names, are just different specific versions of the non sequitur fallacy.

For instance, the fallacy of appeal to popularity calls out the fact that it does not follow from people agreeing on something, however large their number, that the subject of their agreement is true.  The fallacy of composition points out that it does not follow from one object or person being a certain way that other objects or people will be the same (one car being red doesn't mean another car is red; one person having a fierce personality doesn't mean another person will have the same personality).  Appeal to tradition is invalid because it does not follow from something being traditional, say, a law or a social expectation, that it is therefore true, good, obligatory.

When many other fallacies are recognized as articulate types of non sequiturs, it becomes apparent that the non sequitur is a very popular fallacy indeed--one can kind some variant of it in the words and worldview of a great number of people.  Thus, it is imperative that people understand what a non sequitur is, so that they can readily identify it when it appears.  In fact, realizing that many fallacies are different applications of the non sequitur fallacy can make it easier to notice a broader range of fallacies.

While some non sequiturs, like the existence of dragons being proven by Socrates being mortal or Donald Trump being an alien because he is narcissistic, will probably be called out by a large number of people, many of them are far more commonly accepted.  An example of this is the belief that the past has existed for more than a single moment--it doesn't follow from having memories of times before that that the recalled events actually happened.  Another example is the belief that something is morally right or wrong because one has a certain feeling about it--it doesn't follow from having a feeling that an act or attitude is right or wrong.

Non sequiturs like the ones in these two examples are tolerated, accepted, and even defended by people who would correctly reject non sequiturs in other contexts.  This is due to a lack of intelligence and consistency.  Rationalists must be prepared to point out how even popular non sequiturs are still deeply fallacious, regardless of their defended status in society at large.  Truth is not altered or extinguished by the delusions and ignorance of the masses.