Not sure how many people have pondered the concept or have had to articulate it to others, but I spent some time explaining to one of the new players in my group why certain magic (namely illusions and “mind affecting magic”) doesn’t work on creatures that don’t reach past a certain threshold of intelligence.
It boils down to sentience and cognition.
Here’s the question and a very brief primer -
If a creature is of a different mind, how can it understand the magic you use?
While animals and beasts are usually the targets of these discussions, there are many more creatures where magical effects get muddled. In Pathfinder and older systems of Dungeons and Dragons, certain creatures were given the classification of “mindless”, usually represented by an Intelligence of “-” in the stat block; creatures under this umbrella include oozes, undead, plants, “vermin” (another umbrella including giant insects and swarms) and constructs. Mind affecting magic, such as the many different schools of illusions and certain enchantments, doesn’t work on any of these creatures. Older systems made you dig for the fact that an illusion wouldn’t work on an “ogre spider”, but 5E will have exceptions to effects in spell descriptions.
So why doesn’t specific magic work on specific creatures? Depends on the context.
-In the case of animals and beasts, it goes without saying that there is an obvious disconnect between the cognition of humans and animals. As an example, we can understand how the mind of a dog works from a scientific standpoint and dogs certainly have some semblance of intelligence, but any approach to reasoning with an animal is based on what is understood about their behaviors, reactions, and ability to perceive. In general, humans don’t know or understand the full extent of a dog’s cognition. So if a wizard uses an illusion to produce a treat in their hand and produces it to a dog, the dog would be wondering why this person wants their palm licked; not only does the dog not understand what the wizard’s intent is, the dog’s senses would also allow them to discern the ACTUAL treats are somewhere else on the wizard’s person. All this to say that we might be able to fool the senses of an animal but not necessarily its mind, and not solely because we’re “smarter” than the animal. Humans can perceive 3 types of colors; a mantis shrimp can perceive 16. How the fuck can a human mind produce a pattern to fool something that can see colors that we don’t have names for?
-Plants, giant insects, and oozes operate on instinct and a basic desire to consume, reproduce, and survive. Harder to say in the case of oozes since they’re anomalies produced by magical energies and also fictional, but I digress. These creatures, while capable of problem solving and adaptation, don’t posses a cognition or a sentience that we can recognize or “negotiate” with. It is in this group that you also encounter the concept of hive minds or gestalt consciousness via “creatures” such as swarms. A collection of minds acting in flawless unison is a frightening concept to some, and while apostrophe or “alien” on its own, it could be believed that in order for such a thing to exist there must be no individuality in the minds that make up the greater one.
-Undead and constructs are typically creatures that are animated by magical forces of some sort, so their purpose is dictated by the force or person that gave them “life”. There are certainly some intelligent undead and instances of hive minds in this group, but at its basest form, an undead creature is animated by negative energy, another umbrella term to embody the distilled dark side of the many different sentient creatures that exist. This in turn makes the general portrayal of undead creatures one of impending doom, malevolent or unrepentant consciousness, and insatiable hunger (among other things). Constructs take form as something designed for a specific purpose. They are the closest thing to computers or “virtual intelligence” that a fantasy setting can conjure short of homebrews. With all that in mind for both constructs or undead, there is no mind for someone to fool as they were created through certain intent and won’t deviate from their “purpose”.
These are my own notes, of course, but maybe the best way to answer the initial question is this -
How well do you understand the mind of those you wish to fool, bewilder, or bewitch?
One caveat, as always - There are exceptions to every rule.
