20th World Congress of Philosophy Logo

Philosophy of Science

First Revelation: When Theoretical Becomes Visible

Hernán Miguel
Universidad de Buenos Aires, Argentina

bluered.gif (1041 bytes)

ABSTRACT: En las teorías científicas se postulan entidades teóricas que de alguna manera se relacionan con lo observable. Sin embargo con el avance científico y tecnológico, los científicos a menudo sostienen poder observar, co ayuda de algún artefacto, las entidades que tiempo atrás habían sido postuladas por la teoría. Esta transición de algunas entidades del reino de lo teórico al de lo observable con carga teórica presenta características interesantes para un análisis sobre la articulación de las teorías. En este trabajo se presenta una descripción de tal transición en la que se pone en evidencia que además de la aceptación de la teoría involucrada en garantizar el funcionamiento y construcción del artefacto, la carga teórica asociada a la observación con instrumentos, también se debe aceptar un postulado de reducción que establece una relación entre entidades pertenecientes a distintas teorías. También se sugiere una dificultad intuitiva en sostener una postura antirealista de entidades teóricas frente a la posibilidad de que tales entidades puedan revelarse como ‘visibles’ con la ayuda de algún desarrollo tecnológico aceptado por la comunidad científica.

bluered.gif (1041 bytes)

I. If I can't see it I can't believe it

The problem concerning the distinction between theoretical (1) and observable entities can be put in the following terms: entities that can be detected by means of our senses in an intersubjective way should be stated as observables, while entities whose existence seems to be suggested by some theory, but that were not detected even through indirect methods until that moment, should be considered as theoreticals.

Of course, as these theoretical entities are embedded in a theory which also refers to observable entities, we can learn something about them because of their connection with those predictions of the theory (2) which can be directly tested.

We can now extend the notion of an observable entity much further than the limits our senses impose to us, making it possible to consider as observable even those entities that can be detected with the aid of some device or any other reliable method. These entities are thus observables, although they are now theory loaded.

Both ends of this distinction between observable and theoretical entities seem to be clear. But, the harder the detection of an entity is, the closer to each other the intuitions of "theory-loaded" and "detectable by means of predictions" become.

In other words, theoretical entities proposed by a theory are in connection with observable ones. From these connections we can get some relations between observable entities, these relations are the basic stuff used to test theories. Namely, we are testing those features which are ascribed to theoretical entities by means of their consequences in the realm of the facts: that is, by means of the of the theory's predictions.

Unfortunately, this is also true for theory-loaded entities. Every feature of a theory-loaded observable entity has to be taken into account when deducing predictions. However, these predictions are not obtained only from the theory plus some isolated auxiliary statements, but from a theoretical background which, along with the principles of the theory itself, states a basis to derive those predictions.

As we have already said, theoretical entities, despite their status, are linked to observable ones so that their features could be relevant to lay down empirical results where theoretical entities are involved (at least in their explanatory role). This is the reason why the interest arises in order to discuss whether something referred by the theory through its theoretical terms exists indeed in nature, or these terms are only useful tools (conceptual tools) in order to derive our predictions.

The first option expresses a realist (R) approach, while the second one expresses an antirealist (AR) point of view.

In the second approach we can distinguish two ways of denying the existence of theoretical entities:

  • (IAR) instrumentalist: theoretical terms do not denote any object in the world, but they denote useful concepts for making calculations (predictions).
  • (PAR) positivist: theoretical terms are the way we briefly refer to complex empirical phenomena.

There is, of course, a correlation between these approaches and the way theoretical statements are to be considered:

  • (R) general statements containing theoretical terms are considered to express natural laws.
  • (IAR) these theoretical statements are thought of as rules to be followed in the process of generating predictions.
  • (PAR) the theoretical statements containing also observable entities, are an abridged way to express complex empirical laws, whence these statements play the role of correspondence rules rather than being a bridge between observable and theoretical entities, as it can be understood within a realist framework.

2. When theoretical 'things' become visible...

Our analysis should explain a very interesting fact: technological developments allow us to "observe" things which had been proposed by some theory before these developments were achieved. (3) X-rays, electrons, neutrons, etc. are detectable nowadays with the aid of certain devices whose way of functioning is described and supported by some other theory currently accepted by the scientific community.

The fact that we trust in such a theory constitutes the theoretical load of the observation.

This commitment with the theory which "rules" the functioning of the detector allows us to observe a brand-new world full of things and processes.

- ¿What kind of things and processes are you talking about? -shall an instrumentalist say.

- ¿What kind of instrumentalist should be this one? -one might ask.

The problem is rather serious:

For the instrumentalist, the tensiometer's needle doesn't indicate the value of the patient's blood pressure, it is only a useful number in order to calculate whether the patient must take or not a certain medicine of which, similarly, it would be nonsense to say that it is composed by molecules of a certain drug, and so on...

Instrumentalists talk as if certain things existed but they do not really believe it. Besides, with the technological developments their way of talking in their calculations resembles more and more the talk of a realist. Furthermore, according to their view, the existent world, made of observable things, is separated from the inexistent one, made of theoretical concepts used as calculation tools, by a boundary line emerged from the shape, design and limitation of our senses.

Then, the ontology of an instrumentalist dog has more sounds than that of an instrumentalist scientist.

On the other hand, the theory load associated with an observation consists in the acceptance of a theory. And what does this mean to an instrumentalist if not the acceptance of a calculation rule? Then, some objects seem to exist if and only if the instrumentalist thinks that certain theory is a correct calculation rule.

3. To Reduce, to Reveal, to Observe.

3.1 True Epistemology in Science Fiction.

Suppose that once upon a time in the history of science (no matter what this means to us) a theory was proposed to describe the movements of the "swallow-crabs". Swallow-crabs are a kind of migratory crab, half a crab and half a swallow. To explain how swallow-crabs keep the heading during their undersea navigation, it is proposed that every swallow-crab has two navi-needles. This navi-needles determine the direction in which swallow-crabs will move. Both navi-needles head North during April and May, and head South during September and October. The rest of the year, the navi-needles point in opposite senses so that in such a case there is no privileged direction for the swallow-crab to move.

This theory has at least two more predictions other than the latter explanation. If a swallow-crab is located in the middle of its migratory way during January, it will stay there and will not complete its way home until April. We can also deduce that if a swallow-crab is restrained to move in an East-West path (a pipe, for instance) during April, it will not begin to move any direction.

Let us continue with our story and say that this theory successfully explained during the next two hundred years the behavior of migrating flocks (or should I say shoals) every year.

A certain day, a scientist proposes that navi-needles are neural discharges along the swallow-crab's dorsal nerves. One effect of this discharges is to activate the legs in the right direction (already known).

Later, a device was designed to detect nervous pulses and its direction of propagation. It was called "the navi-needlescope". After that, with the addition of a scale to measure the pulses and their direction, we get the navi-needlemeter.

Its designer was awarded with the Nobel prize for Biology that year.

Actually it was possible to confirm that swallow-crabs experiment pairs of neural discharges on dorsal nerves during April and May; each discharge of the pair at each side of its back. The direction of propagation of these pulses is North. During September and October, instead, the direction is South. And the rest of the year, both pulses propagate randomly heading North, South, East and West. Finally, this pulses activate the muscular system of swallow-crabs so that they move in the direction resulting from the addition of both pulses.

Neural pulses are electric polarization pulses and owing to a wide development of the theory of electricity in those years it could be possible to built up the above mentioned detector.

Now, in order to "observe" the navi-needles we must put a detector over the swallow-crab and the device will immediately display the intensity and direction of the navi-needles.

The scientific community has accepted the theory of electricity that describes and supports the functioning of these detectors. Therefore we can trust them and finally accept that we are observing the navi-needles.

Two independent conditions have to be fulfilled in order to consider that navi-needles can actually be detected and observed by means of these detectors, and then to consider them as observable, although theory loaded:

1st) The development of the theory of electricity to such an extent that there is a consensus for its acceptance as a support of the analysis of neural pulses.

2nd) To set up a new statement relating the navi-needles with neural pulses. I will call this statement "reduction postulate".

This postulate is a different kind of statement than the others. Earlier statements belong to the theory of navi-needles and swallow-crabs. But this new one is a kind of connection between two theories: that of swallow-crabs and that of neural pulses.

This statement represents a connecting law describing a factual relation between pulses and navi-needles. (Although a positivist would affirm that we only redefine certain terms.)

The theory of swallow-crabs, with its navi-needles, is reduced to that of neural pulses and together with the developed detector reveals the image of navi-needles.

As in a photo lab we face a revelation of the navi-needles in the detector. The boundary line between theoretical and observable entities has been shifted drawing aside the veil that yesterday hid the navi-needles and showing us the success in having conjectured them two hundreds years before.

3.2 Mendel's navi-needles

As the audience can imagine there are real stories with these features in the history of science. For example, let's take the reduction of Mendel's theory to that of molecular genetics.

Currently we observe the sequence of nucleotides in the DNA and detect the genes determining the characters of a plant.

The genes proposed by Mendel (4) are obviously theoretical when considered in the frame of his theory, but can be detected with the aid of the microscope developments and the commitment with the following additional statement: "The genes are nucleotide sequences".

Now, we can say that we observe the genes if we accept the two following items:

1) theory of tunneling microscope.

2) additional statement: "The genes are nucleotide sequences"

It is not a novelty that genes become theory-loaded observable entities.

But it should be noted that we usually speak of "theory-load" in relation to the acceptance of item (1) while we do not pay attention to the item (2).

I have named the item (2): "reduction postulate".

And it is my opinion that an entity that has been labeled as theoretical because it was postulated in a given theory with a certain explanatory role will change its status into a theory-loaded observable one under the following condition:

a technological development is achieved, based on an accepted theory and in addition it is used for the detection of an aspect related with the entity in question by means of a reduction postulate.

I accept that the entity will still be theoretical when it is classified within the frame of the original theory. But this new criterion may cast light on the way scientists refer to observation in a generalized manner. It also shows how scientific and technological developments are taken as a shift of the demarcatory line between the observable and the theoretical.

4. Conclusions

I want to point out that when an entity is classified in the frame of the theory in which it was originally proposed, it continues being anchored to the conjecture in the theoretical realm.

This internal feature which consists in keeping its theoretical condition inside its own theory does not contribute at all in analyzing the process by which scientists announce (and believe) that they have finally observed the entities whose existence was proposed before.

Instead, in order to obtain an explanation of this process we should look into the relation between these theoretical entities and the other theories.

I tried to show that it is necessary to state a reduction postulate in addition to the acceptance of what we usually call "theory load", for the entity (previously theoretical) to be considered observable by the scientific community.

Finally I suggest that this process, and the consequent acceptance of the existence of the entity in virtue of its observability, generates an intuitive bias respect to the way antirealists treat theoretical entities.

bluered.gif (1041 bytes)


(1) In the present work I will use "teoretical entity" to refer those unobservable entities appearing in scientific speaches and embedded in propositions of some theory. I will use this terminology yet one can rise the reasonable objection that some theoretical entities (proposed by the theory) can be observed: for instance, the east coast of India whose existence can be inferred from the round Earth's theory (in conjuction with other auxiliary statements) before Columbus trip's time.

(2) No prediction can be obtained from the theory alone. Although is a commonplace assestment that are necessary auxiliary statements to obtain them, there are a few more considerations to be pointed out. See Hempel, Carl. "Provisos: A Problem Concerning the Inferential Function of Scientific Theories." in The Limitations of Deductivism. Grünbaum, A and Salmon, W. (1988) Berkeley and Los Angeles. University of California Press.

(3) I am grateful to Samuel Cabanchik for his comments by the end of 1996 that made me pay attention to the process that takes place when an entity "crosses" the boundary of our clasification from theoretical to theory loaded observable.

(4) We are talking of the theory as it was rediscovered in 1900. It seems that Mendel had never proposed the existence of a pair of genes. See Mundo Científico Vol. 4, N 34, pp 275-287.

bluered.gif (1041 bytes)


Back to the Top

20th World Congress of Philosophy Logo

Paideia logo design by Janet L. Olson.
All Rights Reserved


Back to the WCP Homepage