In an attempt to widen my horizons I have been listening to the Philosophy Now podcast out of the UK. A recent episode concerned philosophy of science (ep 29) and the host asked an interesting question: “Why do we have to have experiments when sometimes we can get away with observations?”.

The point he was trying to make was that when we think about science in an abstract way we also have the idea that experiments are at the core of the scientific method. This clashed somewhat with the person the host was talking with at the time who was emphasising observation as the way we confirm hypotheses in science.

The implication here is that we have two things, observations on the one hand and experiments on the other.

This appears to be a fairly common view, I have seen arguments accusing cosmology (specifically the big bang theory) of not being science because you can’t perform an experiment to create a new universe. Similar arguments have been made for evolution.

I don’t know how widely held this view is in the general population (as opposed to those who are set against certain findings of science) but the question of the podcast host implies that it’s wide enough.

The problem with this view however is that there really aren’t two things here that are different in kind. Rather, one is a sub-set of the other; experiments are a special kind of observation.

The whole point of an experiment is to interrogate nature in a specific kind of way. While we can passively observe an event and gain valuable information (say, watching the development of an embryo) we can also create an experiment that constrains the conditions in a particular way in order for us to draw more conclusive conclusions about the situation of interest (perhaps we knock out a gene and watch that embryo follow a different developmental path).

By using experiments we aren’t doing anything fundamentally different, we are still observing what nature has to tell us about the world we inhabit, but we are trying to set up conditions that are meant to clarify what nature is saying. In this view experiments are nature’s interpreter.*

Experiments also allow us to get access to things that we might not normally be able to see. For example high energy physics requires elaborate experiments in order to allow us to in some way visualise particles that are mind bogglingly small. We aren’t creating the physics we observe we are simply delving into realms that would normally be hidden from us.

This was brought home to me a few years back when the attempts to listen for extraterrestrial signals by SETI were referred to as experiments. In this case we aren’t setting up the conditions by which we control whether an ET sends us a signal, we are determining the conditions by which we would receive such a signal. At it’s heart this activity is an observation, no different in it’s intent from viewing a microbe under a microscope.

So it is that the ability to do or not do a experiment does not determine science from non-science (termed the demarcation problem and certainly not definitively settled). Experiments may have come to be thought of as the defining feature of science but they are really just a special case of something we all do every day – observe the world around us.


*If that’s too narrow for you, how about experiments as nature’s speech therapist?

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