How to Use the Taxonomy

Beginning with Aristotle, the first logician to name fallacies, most logicians who have studied fallacies have classified them into types. Aristotle classified his list of fallacies into two types:

  1. Linguistic: Those that depend on language.
  2. Non-linguistic: Those that do not depend on language.

Subsequent logicians have usually extended Aristotle's classification by subdividing the second, non-linguistic, category into sub-categories―for instance, fallacies of relevance and fallacies of presumption. However, most such classifications have remained relatively "flat", with all fallacies on the same level. Unfortunately, a flat classification does not do justice to the complexity of the logical relations between different fallacies.

The Fallacy Files Taxonomy is a tree-like structure that classifies all of the fallacies in these files by the sub-fallacy relation. A sub-fallacy, which is a specific version of a more general fallacy, has whatever features the more general fallacy has, together with specific features which set it apart and make it worth naming in its own right. For example, instead of grouping together "fallacies of relevance", there is one most general such fallacy—namely, Red Herring—and all fallacies of relevance are sub-fallacies of it. Red Herring is itself a sub-fallacy of Informal Fallacy, which is a sub-fallacy of the most general logical fallacy of all: Logical Fallacy. Logical Fallacy is, thus, the top node of the Taxonomy, for every fallacy in the Taxonomy is a sub-fallacy of it. The sub-fallacy relationship is like a tree with a trunk―Logical Fallacy―which branches until it reaches leaves, that is, fallacies which have no sub-fallacies―for example, Appeal to Celebrity.

To use the Taxonomy to navigate to the entry for a particular fallacy, simply click on the node for that fallacy.

There are now two versions of the Taxonomy available for use:

The Taxonomy is more useful than the alphabetical index for studying the logical relationships between fallacies. To understand an individual fallacy, it may be helpful to move upward in the NT―that is, to the left in the OT―in order to understand the more general fallacy of which it is a sub-fallacy. Also, moving downward in the NT―that is, to the right in the OT―can help in understanding a general fallacy through seeing more specific versions of it.

In addition, fallacies that are sub-fallacies of the same general fallacy are like siblings, since they share the same parent. So, it may help to compare and contrast a fallacy with its siblings. As with human siblings, the likeness between sibling fallacies is stronger in some cases than in others. For instance, the causal fallacies Post Hoc and Cum Hoc are more similar to each other than they are to their other siblings, the Regression and Texas Sharpshooter fallacies. In the OT, this strong sibling relationship is indicated by a thicker, similarly-colored line connecting the two fallacies. In the NT, unfortunately, this close sibling bond is not explicitly represented, but similar fallacies are placed next to each other on their common branch.

Another use for the Taxonomy is in finding a fallacy whose name you don't know, but you do know what general type of mistake you are looking for. Start with a general fallacy, and "drill down" into the Taxonomy―that is, moving down in the NT or to the right in the OT―until you find what you're looking for. Happy fallacy hunting!

Technical Appendix: Mathematically speaking, the sub-fallacy relation is a partial ordering of the set of fallacies. In terms of graph theory, the Taxonomy is a cyclic graph. As mentioned in the section above on the OT, it is not actually a tree in structure because some fallacies are leaves on more than one branch, though this characteristic cannot be shown in the NT for technical reasons. Specifically, at the level of HTML, the NT is simply a nested list. While it would be possible for the same fallacy to occur in different sub-lists, this would create duplicate nodes rather than show a single node on multiple branches. The NT is already tangled enough without this additional complication.

The OT is an image and uses an image map to create the links from the nodes to the individual fallacy entries. As you can imagine, this made it extremely difficult to update the OT with new fallacies since the entire image might need to be redrawn and much of the image map changed. As a result, the OT is missing at least one fallacy, namely, Overgeneralization. As new fallacies are discovered, the OT will fall farther behind.

As mentioned above, the NT is a nested HTML list and the tree diagram is drawn using a Cascading Style Sheet―that's right, no Javascript needed! This is the main reason for adopting the new version as it will be much easier to update than the old one. Unfortunately, some of the structure in the old version cannot be rendered in the new one, namely, the close sibling relations and the graph cycles.

Also, three fallacies have been temporarily omitted from the NT: Composition, Division, and Loaded Question. The latter never fit well in the OT, and the former two need a more general super-fallacy that currently lacks an entry. Hopefully, the latter omission will be corrected soon, though Loaded Question may belong elsewhere. The Taxonomy, as the rest of The Fallacy Files, is a work in progress.

Source: CSS3 Family Tree, The Code Player. The NT was adapted from this CSS code.

Acknowledgment: Thanks to Daniel Nussdorf for pointing out a mistake in the new taxonomy.