I was asked the following question on Quora:

What kind of information do we need to discover everything about memory in the brain and its mechanism?

I took the opportunity to recapitulate an excellent point made by Paul Feyerabend in his book Against Method, which I am currently reading.

Here’s my answer:

We’ll need to collect information at the genetic, synaptic, cellular, network, and behavioral levels (and perhaps even environmental and social levels), and integrate them into a single picture of memory in action. In other words neuroscientists are already more or less on the right track. Sometimes we know exactly what we’d like to study experimentally, but we lack the technical ability to do so. (For example, our non-invasive techniques for measuring human neural activity are extremely coarse-grained and indirect.)

But I don’t think it is possible to know in advance what specific kinds of data will prove decisive in the creation of a comprehensive theory of memory. Every new experiment can potentially throw up new theoretical questions. We can’t anticipate the evolution of a scientific research program, because we lack the very thing we are searching for: a theory that tells us what is important and what isn’t. If we already had a perfect theory, it wouldn’t be research.

We typically think of experiments and theories as completely separate entities. So we imagine that science involves a linear process like this:

observation -> theory -> new observation -> new theory ->

…and so on. But this doesn’t really capture how science actually proceeds. Think of it this way. Before we have a good theory, our observations may be contaminated by the old partially-successful theories. A theory — even a half-baked one — comes with its own ontology of what exists and what doesn’t. Experimentalists have their own working models and rules-of-thumb that tell them what is worth recording/analyzing and what isn’t. Some of these models and rules may prove wrong, once a good theory comes along. But before that theory comes along, we can’t say much about them. Theory and experiment are intertwined –each can reinforce (or refute) the other.

Philosophers have pointed out for a while now that experiments are not just true pictures of the world — they are intrinsically theory-laden. Theory goes into both the design and the analysis of experiments. This doesn’t mean they are not to be trusted. It only means that in the periods where there is no obviously successful theory, you cannot say which experiments will prove to be the building blocks of a future theory, and which will eventually prove to be wrong or in need of a fresh interpretation.

To sum this up: if we find ourselves in an unlit room we’ve never entered before, we have no choice but to fumble around in the dark until we find a light switch. We can’t anticipate our trajectory through the room — but after we find the light switch, every stumbling step and bruised toe can be restrospectively explained.