As difficult as it is to imagine a novel and useful set of facts, or some new way of doing things, the difficulty is much greater when what may prove useful is how nature does something. For unlike facts, or a made thing whose function we can easily test, we cannot directly observe nature at work. We see results and have to imagine what happened.

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THEORY

Let’s be as clear as possible about what theory really is. We have the real world, filled with facts about things, and things themselves. How did it get that way? That is theory. Where do stars come from, the great whales who swim the seas, humans, and the diseases that afflict them? It is all imagined, and yet solid enough we live our lives as if what we believe were true.

Why do we believe our theories? Simply because they predict things. When I say things, I mostly mean facts about things that we can readily perceive. The way we envision the formation and life of a star lets us predict things about the stars we can see, and those predictions are more often right than wrong. Likewise for all the living things in the world. For them we have the great theory of evolution. Medicine concerns disease in humans, and it is the same. Because our theories predict things about disease, we believe them. As a result, physicians use facts, tests, treatments, and theory.

THEORY AS AN OBJECTIVE – The Case of Medicine

 Imagining the Objective

The objective of a scientific research is always imagined, because we don’t have it. Here, what we are after is a cause, of some component of a disease or of the disease itself. How much better for treatment to aim at cause than consequences. As for facts and invention, we begin with imagination, but one perhaps more difficult because we are after nature’s hidden and mysterious ways.

Though we cannot know how the mind imagines, surely required is mastery of what is there, and of those causes already accepted. The result, shown in a green box, will be of the form  ‘this causes that’. Red is imagined, white can be observed. This imagining is the desired objective. But it is useless, mere conjecture, until it demonstrates predictive power.

Imagining the Test

What are the necessary consequences if the imagined cause were true? Necessary means a logical requirement, inevitable and undeniable. Useful consequences must also be directly observable as things or facts about things.

I am not sure we know how scientists come to the right test. Surely, one can imagine a test and then examine it for logical connection. Can necessary consequences be deduced by logic alone? I do not know. Certainly, without a combination of logical thinking, imagination, and, of course, mastery, prospects seem glum. The choice of the test is not an easy thing.

What Kind of Test?

Up to now we have empiricism. So a test would involve the search for some set of facts about things predicted by the theory. But there is another path, to make a deliberate change and predict its consequence. The name is experiment, meaning a contrived experience. We are not measuring things in the real world as it is, but in a world changed by us, in a deliberate manner, according to theory – to an imagined idea about how nature does things.

 Empiricism vs. Experiment

Both are measurements of things. The difference is whether of the world as it is or as we make it. I have said empiricism without hypothesis has a limited value – apart from mere expansion of knowledge. Experiment without theory is itself absurd, as the change we make takes its meaning from theory.

THEORY AND KNOWLEDGE

 The Logic

In the white box, an ‘all statement’ – about causality in nature – is proposed in a logic named the Modus Tollens, or denial of the consequent leading to denial of the antecedent. The consequent, a logical necessity, is singular – a single observable set of facts in the world as it is or as altered by an experiment.

If true, then the ‘all statement’ is not falsified at this point. But another test may falsify it at any time. Popper refined and elaborated this reasoning in ‘The Logic of Scientific Discovery’. His writings have marked him as a doleful sceptic that humans can ever come to some universal and ultimate truth about nature.

The Empirical Project

Another way to look at the logic is to ask if any number of singular statements can give rise to an ‘all statement’ without a need to imagine – give rise via logical necessity. He argues that is impossible. I have no reason to remake his arguments here. But he means by this that imagination is not decorative, but necessary for real progress.

The Process of Transformation

Even so, there is magic glimmering within the white box, for the Modus Tollens can transmute imagination into measurement. And measurements, when they confirm the vision give us, if not hope for any ultimate and final knowledge at least surety that what we believe has value enough we can use it for medical care. Rely on it for now, keep testing.

The Emotion of Testing

We do not test to confirm, but to deny. The former is downright dangerous. All of our desires should aim at denial, so that confirmation gives us belief well earned. We cannot afford to love our dreams, at least in science, for they surely will betray us if we let them. Thus, Popper, with verve and energy, warns us to construct as powerful a denial as possible – savage, distrustful, and resolute.

THEORY AND INVENTION

Invention. We imagine that things in nature can be used to make a new thing, of our own design. A thing fashioned to perform some actions we desire. Mastery, surely. Imagination, too. The test is secure. We make it and it does or does not do what we need it to do. The Modus Tollens can be set to one side. Also to one side all insecurity about the result. Our aim was not to know nature but to use it for our own purposes, and in this we succeed or fail.

But otherwise need we assume invention and theory differ at heart? I think not. One seeks how nature causes something. The other seeks to cause something using what nature provides – for everything comes from the world. I say ‘cause’ something rather than ‘do’ something, but they mean the same. An instrument to ‘cause’ some action or transformation – ‘do’ some work on the world. In medicine a test or treatment.

THEORY IN MEDICINE

 I will return to this but for the moment consider that disease manifests itself as facts in the real world of a human body. Like all such facts, one would like to know their causes. It is this desire, to treat and test for causes, that we use theory in medicine. The underlying idea, that prevention and cure require we know causes is not without truth.