A colleague recently relayed a story to me about an experience they had while interviewing for an assistant professor position in a well-respected psychology department at a Research I university. During one meeting with a successful, tenured professor who is known for being outspoken, the interviewer looked into my colleague's eyes and asked, "So, are you with the ‘babies are smart' camp or the ‘babies are stupid' camp?"
To those outside the field of developmental psychology, this may seem like a very odd question to ask someone. And yet, it's a perfectly accurate illustration of how the field of developmental psychology is polarized. On the one hand, you have researchers (like Leslie Cohen, Kelly Mix, Scott Johnson) who believe, true to Locke, that babies are born "blank slates". That is, they know nothing of how the world works - babies are stupid. On the other end of the continuum you have researchers (like Liz Spelke, Renee Baillargeon) who would claim that babies are born with rich, detailed knowledge of the world - babies are smart.
In all fairness, to my knowledge, there are no researchers who subscribe to the extreme nativist position, which would be that ALL knowledge is innate. Clearly, this can't be true. Instead, current nativists tend to appeal to a "core knowledge" view proposing that infants are born with principled knowledge in a few core domains and use this knowledge to make predictions about how entities in the world act and interact. And the domains they have knowledge of are precisely those that would promote survival - e.g., objects, people, number. The logic being that leaving something as important as a basic understanding of people or objects to learning (which may or may not occur) would be risky, so instead, evolution built the knowledge into the organism.
To string this line out along a different dimension, you could think of it in terms of learning and how much or how little an infant needs to learn in order to develop into a typical adult. On the "stupid" side of things, babies are seen as having to learn everything. That's right, everything. And, to help them achieve this, they have only a handful of "general purpose" processes at their disposal - associative learning, statistical learning, habituation - basic processes that help them detect when two events occur together in space or time, or recognize that the thing they see now is the same as or different from the thing they saw a moment ago. On the "smart" side, their core knowledge provides them with basic principles in a few domains that are critical for survival. The principles further function to guide infants' learning by directing their attention to relevant information out in the world. So, really, both sides believe that a lot of learning takes place, it's really more of issue of what the newborn state looks like - empty or populated with skeletal, foundational knowledge upon which acquired knowledge can be built.
So what? Who cares if developmental psychologists disagree about the initial state of the human mind? Well, if you're a parent, you should care. Beyond it being an age old, interesting, philosophical question, understanding the truth about whether babies are "smart" or "stupid" can put us on the right track so we can find out what knowledge young children take with them when they enter the classroom, which is critical if we expect to be able to design effective educational aids and early education curricula. Even in the home, it can help parents know what to expect from their kids at different ages. As parents, arming ourselves with as much information as possible about our children and the likely course of their development can help alleviate some of the stress that accompanies parenting. And less stress makes us better parents. Everyone can agree on that.