In Descartes' Baby, Paul Bloom engagingly writes about research that shows babies are more sophisticated than we usually give them credit for. At a very early age, babies are aware of the constancy of objects, that appearances may be deceptive, and that other people may hold false beliefs. The problem is what Bloom makes of this.
Bloom thinks those experiments prove babies are Cartesian dualists because they distinguish objects from belief-holding humans. But dualism isn't simply the belief that there's a difference between people and objects. We were making that distinction before Descartes. Cartesian dualism conceives of the mental and the physical as so distinct and different that it doesn't seem the two could ever even interact. And that's not a distinction babies make. If "dualism" means that we distinguish conscious critters from inanimate things, then, yes, we're all dualists. But what have we learned except a new definition of "dualist"?
Baby dualism isn't even necessary dual. I can believe that you are different from a log because you are aware of and care about your world without thinking that you are made of two types of substance. I don't think Bloom has shown much more than that babies are aware that logs don't think and feel but people do.
This "insight" doesn't give Bloom much of a lever for understanding the Big Issues he deals with: Art, philosophy, religion, ethics... For example, he wonders how we can be moved by "anxious objects," i.e., art such as Warhol's Brillo boxes or conceptual art such as a dead horse hung from the ceiling. Most of the chapter goes through the predictable explanations of why we respond to art. At the end he acknowledges that he hasn't yet explained the appeal of "anxious" art. The big explanation: "...We enjoy displays of skill, of virtuosity, both physical and intellectual." But that's true of non-anxious art, and not true of all anxious art. Without acknowledging this, he moves on to say that we enjoy anxious art because we can see the human intention in it. But, again, that's true of all art, not just anxious art. His investigation does not come close to answering the question he raises. (Artworks are a good example of the impossibility of separating the physical and the intentional...evidence against dualism.)
Likewise, his explanation of why children tend to believe in Creationism (AKA Intelligent Design) - it is "a natural by-product of a mind evolved to think in terms of goals and intentions" - doesn't help. Animism also seems to be a "natural by-product." So what? How does this socio-biological explanation help? Likewise for his explanation of altruism, his discussion of essentialism - which waters the concept down the way the book waters down "dualism" - his consideration of the origin of religious beliefs, etc.
The book is exceptionally well written and engaging. The baby research is fascinating. But I think it fails as an attempt to make something big out of that research.