Observations and Inferring
Observations are pieces of information that we get directly from our senses – sight, hearing, touch, smell and taste. People who are described as "observant" tend to make detailed and accurate observations.
A naughty dog that has made a mess. Right?
That might be what happened but you can't actually see the dog making the mess. This is what you think happened based on what you see.
To be precise, what you can see is a dog sitting on a brown tiled floor. The dog is surrounded by some broken plates, paper and rubbish. These are direct observations.
Until we have more evidence, we can't be sure that the dog was to blame for the mess. So A naughty dog that has made a mess is not an observation. It is an interpretation of what happened before the picture was taken.
Inferences are ideas that we come up with to explain our observations. Inferences are not necessarily true and there can be more than one possible inference for any observation.
The idea that the dog made the mess is an example of an inference. It is supported by what you can observe, but other inferences could also be made on the basis of the same evidence.
Remember, observations are things we can sense directly. To check that something is an observation, ask yourself if it makes sense to say, "I can see...", "I can hear...", "It tastes like...", etc.
For the picture on the left, you could say, "I can see cracks in the road." That is an observation.
On the other hand, it would not make sense to say "I can see an earthquake." We might think that an earthquake caused the cracks in the road, but that is an inference.
As we make new observations, our inferences might change to take this new evidence into account.
To explore this idea, imagine you're a palaeontologist. You've been digging for fossils and made an exciting discovery: a set of footprints preserved in a layer of rock!
Do you think you could figure out what an object is without looking at it?
One secret to being a good observer is to use your different senses. What does it feel like? What does it sound like? What does it smell like?
The aim of a scientific theory is to describe or predict natural events. Theories allow us to make inferences about what we observe. The observations are evidence that help to support the theory.
To test a theory, we need to make a testable prediction. We can then conduct an investigation to test whether the prediction is correct. The results might provide more support for the theory. If they do not, we need to change or reject the theory. So our scientific theories change over time as we gather new evidence.
Scientific theories are based on repeated investigations and observations. Through this process, we aim to find the best explanation for the evidence. Testable predictions are key to this process. Without them, our scientific theories may be inaccurate or false.
Let's look at an example.
In the 19th century there were scientists called phrenologists who spent a lot of time measuring people's heads. They had a theory that the size and shape of someone's skull was evidence of their personality and intelligence.
This theory was an inference based on two pieces of knowledge:
the brain is responsible for thought and behaviour, and
the brain is made up of different parts.
Since then, psychology and the science of the brain have made advances. This has allowed us to more accurately test how the brain functions.
Scientists have shown that personality and intelligence can be linked to certain parts of the brain. But they don't relate to the size and shape of the skull. Phrenology was abandoned because new evidence gave us a better explanation.