The first difficulty in discussing "animal intelligence" is figuring out what we mean by that term. In its most trivial sense, all creatures have "intelligence" of some sort, but in arguments about the nature of animal cognition, intelligence means some sort of abstract reasoning ability like thought or communication medium, like language. But I'll let the experts explain it. If you would like to read about animal intelligence, dog intelligence, or dog training, here are some books I recommend:
If a Lion Could Talk: Animal Intelligence and the Evolution of Consciousness, by Stephen Budiansky.
A personal favorite, even though I disagree with his specific reasoning in some places. Budiansky's position is halfway between the behaviorist/species-centric "Thinking is for humans. No animals allowed!" and the New Age "Worms have aesthetics; just ask your dog!" camps. This in itself gives him credibility, as far as I'm concerned. His book presents a case for animal cognition being a fact, but how animals think being impossible for us to imagine.
Budiansky blasts the New Age crowd for assuming implicitly that "thinking" means "mental activity like ours." He makes the point that this is just a subtler kind of species-centric view than the one the behaviorist asserts explicitly. A very useful book.
The Animal Mind, by James L. Gould, Carol Grant Gould.
Less technical than Budiansky, the Goulds' book is for the general reader. Their examples are weighted against the "No thinking!" folks.
Animal Minds: Beyond Cognition to Consciousness, by Donald R. Griffin.
Griffin is in the pro-thinking camp. This is a gross oversimplification, by the way, partially driven by my refusal to even listen any more to the Cartesian yahoos grunting about being the crown of creation. Nonetheless, Prof. Donald R. Griffin is credited with "inventing" the science of cognitive ethology, which is the study of reasoning behavior in animals. Animal Minds explores forms of communication, making a case for non-verbal communication among even insects.
Wild Minds: What Animals Really Think, by Marc D. Hauser.
Hauser's book is thoughtful and intelligent, and meant for general audiences. Like Budiansky, he takes a middle-road position, though his debunking of the "Animals are just like us" folks might make it seem otherwise to them. Focusing on the brain and its functions as tools, he describes the tool-using abilities of a variety of animals.
Inside the Animal Mind: A Groundbreaking Exploration of Animal Intelligence, by George Page.
The companion volume for a PBS series on animal intelligence, Page's book takes a balanced, readable look at the kinds of reasoning animals are capable of.
When Elephants Weep: The Emotional Lives of Animals, by Susan McCarthy, Jeffrey Moussaieff Masson.
Jeffrey Masson is the guru/spokesmodel of the "worms think" folks, primarily on the evocative weight of his essays on animal emotions. But the fact is, he is made to order as a Cartesian whipping boy, because his arguments rest on carefully presented anecdotes, evidence we want to believe, true or not. There is no denying that his books are touching and engaging; but the truth isn something we discover, not something we invent to suit our fancy.
As an example of what I mean, consider that as a dog person, I am taken with Dogs Never Lie About Love: Reflections on the Emotional World of Dogs, but I haven't a moment's interest in his newer book, The Nine Emotional Lives of Cats: A Journey into the Feline Heart. And his children's title, Dogs Have the Strangest Friends, doesn't interest me. In addition to his own books, Masson lends his name to books of even less sound science, like The Compassion of Animals: True Stories of Animal Courage and Kindness, a title that gives me the willies.
Masson's books offer the inside-out species-centric view decried by writers with more balanced views. "Animals are just like us!" Masson and his fellows seem to be saying, "They have ideas, and morals, and everything!" Animals are not just like us. Even we are not "just like us." Different human cultures process and share information differently, as a few minutes with any text on ethnomathematics will show you.
The Hidden Life of Dogs, by Elizabeth Marshall Thomas.
Thomas offers a more balanced view than Masson, though no less passionate. Readable, amusing, and based on personal observations, her book will teach you a bit about how your dog thinks.
Folklorist Roger Welsch (Old Tractors Never Die, Catfish at the Pump, Touching the Fire) has written a collection of essays about dogs not to be missed. Welsch is a Nebraska native with a wonderful Midwestern sense of humor, and his anecdotes are full of wit and wisdom — human and canine. A Life with Dogs is written in homey, conversational style, with titles like "The Other Dog's Whatever" (on doggie envy) and "Passing On" (you know). Welsch loves dogs, and the essays are full of that affection.
The Intelligence of Dogs: A Guide to the Thoughts, Emotions, and Inner Lives of Our Canine Companions, by Stanley Coren.
Stanley Coren's IQ test for dogs, which Crom disdained taking, is a lot of fun, as are his observations about canine intelligence. I've picked up his book on "speaking dog" a few times, but it's a bit too rudimentary for us. He starts with the basics, like "What does that tail angle mean?" (a lot) and "Do dogs grin when they're happy?" (sometimes). Coren's books are a great introduction to how dogs think.
I continue to search for a copy of my favorite training book, which I read when Crom was a year old, nearly sixteen years ago. I've been trying to find it, on and off, for more than five years.
An excellent new training book is available at Amazon. Victoria Stillwell's It's Me or the Dog is clever and helpful.
The key to Stilwell's success is simple: Think about things from the dog's point of view. Exactly.
Stilwell is the host of a popular dog training TV show in Britain.
I think it was Natural Dog Training, by Kevin Behan. The description sounds right. If that's it, then it's back in print. Behan takes the approach that the best way to train a dog is the way his pack seniors would. When I read the book, I especially loved the explanation of why dogs "bite", and his suggestion for the ultimate punishment ("Roll the dog on his back and make him stay there"). Both work with Crom and Link, two dogs as different as Laurel and Hardy.
Another book to look for is John Ross' Dog Talk. Ross, like the other recommended authors, emphasizes that the starting point of dog training is understanding the dog. This seemingly obvious truth is a fairly recent discovery. It has taken humans some time to comprehend the sharp observation of Ludwig Wittgenstein: "If a lion could talk, we would not understand him." The idea that there might be other ways of thinking is a late comer to Western culture. Once you learn to "think like a dog," it's a lot easier to "talk" to your canine friend.
Finally, there is Jon Katz, an excellent trainer with a controversial new book I recommend with reservations. In The New Work of Dogs, Katz argues that in contemporary America, humans develop relationships with dogs as a way of coping with the poverty of human relationships. It places an extraordinary and unfair burden on the dog, he says, and because it happens in a culture that regards animals as objects when it is not sentimentalizing them, it leads to a peculiar form of cruelty — the abandonment of one's "best friend" when a promising human comes along. An interesting and provocative book.