Morgan's Canon

In 1894, the same year Romanes died, C. Lloyd Morgan published a book with a more sober point of view. Morgan's book was titled Introduction to Comparative Psychology. In it, Morgan drew a distinction between (1) objectively testable inferences from animal behavior, which were scientific and (2) untestable speculations about animal minds, such as Romanes's ejective inferences, which were not scientific.

What "modern" sounding distinction did Morgan draw, in his 1894 book?

To use a modern example, you might have a cat that comes running when using an electric can opener. You might infer that (1) the cat is capable of hearing this sound from the other room and has associated its occurrence with the possible delivery of food. This is scientific speculation because it is based on well-known principles of conditioning, and if you wanted to, you could do experiments to test it, such as associating a new sound to food delivery, or comparing the cat's response to different sounds. Or you could do ejective inference, and infer that (2) the cat knows that cans contain food and the can opener is what opens up a can. The ejective inference is not a scientific speculation because it inserts human-level thoughts into the mind of a cat. It also goes way beyond what is necessary to explain the cat's behavior.

Morgan recommended economy or simplicity in interpreting animal behavior. The following declaration from his 1894 textbook came to be known as Morgan's Canon. (A "canon" is a principle or law.)

What was the main idea of Morgan's Canon?

In no case may we interpret an action as the outcome of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one that stands lower in the psychological scale. (Morgan, 1894, p.53)

This idea can be paraphrased as, "Never assume more complexity in an animal's mind than you have to" or "Select the simplest possible explanation for how an animal performs a behavior."

How does Morgan's Canon resemble Occam's Razor?

Morgan's Canon resembles the principle of parsimony in science, sometimes called Occam's Razor. Occam's Razor says a simple explanation should be preferred over a complex explanation of a phenomenon, other things being equal.

Anthropomorphization can be misleading even when it seems to be the simplest explanation for a behavior. Consider the behavior of baby rats separated from their mothers and exposed to extreme cold; they emit ultrasonic vocalizations that observers have always assumed were cries of distress "to stimulate the mother to retrieve the pup to the warmth and comfort of the nest." (That would also be consistent with the attitude of the New York Times article quoted earlier.) However, this assumption turns out to be false, or only half-true. Blumberg, Sokoloff, Kirby & Kent (2000) found that the cries were actually a means to pump more blood to the heart, when the rat pup is exposed to cold. Using a technique that allowed them to reduce venous pressure, they were able to show that the vocalizations occurred whenever blood pressure dropped below a certain level. The cries resulted in "large pressure pulses in the abdomen" which stimulated warming blood flow and kept the pups alive. The authors noted that their findings "underscore the potential pitfalls of anthropomorphic interpretations" (p.78). Of course, the cries might serve a dual function, pumping blood and alerting the mother to a baby outside the nest.

What was Morgan's view of learning and consciousness?

Animal researchers of the 1890s were considerably less cautious than modern researchers, when it came to speculating about the "animal mind." Despite his warning against reading too much into animal behavior, Morgan himself declared that any form of learning was evidence of consciousness. A chick might be "unconscious" the first time it made a peck after hatching from an egg, he said, but when the accuracy of the chick's pecking increased, this showed consciousness, "for only by appealing to consciousness can [pecks] be guided" (Morgan, 1896, p.130).

What reaction to speculations about animal minds occurred? What was Loeb's view?

By 1900 scientists were reacting against such speculations about animal consciousness. Many scientists were ready to stop speculating about "animal minds" altogether. Jacques Loeb (1900) argued for a mechanistic view. He proposed that animals were like biological machines, and that only humans had minds and consciousness. Loeb explained much animal behavior as due to tropisms , automatic movements toward a stimulus. The movement of moths toward light (or slugs toward beer) would be interpreted by Loeb as a tropism, a simple stimulus-response connection in the animal's nervous system. A stimulus led to a response, he said, and no mind was involved.

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