La inteligibilidad del mundo natural

The intelligibility of the natural world

Author: Mariano Artigas
Published at: article unpublished
Date of publication: lecture delivered in Bogotá, 1990.

The question of nature is a constant in the history of mankind. This is logical, since man is immersed in nature, surrounded by it, and even part of it. He needs to know nature in order to survive, to understand himself, to answer the basic questions he faces.

All cultures include, in one way or another, a vision of nature and its relations with man. Western philosophical thought, since Greek antiquity, began its speculative flights of fancy with the question of nature as its pivot. The systematic development of experimental science, from the 17th century onwards, introduced new and enormously effective methods of understanding and mastering nature. One of the fundamental features of today's civilisation is that it is a scientific and technological civilisation. The questions we ask ourselves today are to a large extent conditioned by our worldview, and ecological problems have further highlighted the centrality of our attitude to nature.

In these circumstances, the question of the intelligibility of nature turns out to be a fundamental one. It is not easy, however, to propose immediately obvious answers, and this is due to the issue and the complexity of the problems involved. The following reflections, rather than exhausting the answers, aim to clarify some basic aspects of the problem.

1. Three images of nature

A first reflection, which will serve to frame the others, leads us to consider the succession of worldviews throughout history. It is generally agreed that, broadly speaking, there have been three great worldviews.

The first, typical of antiquity, is the organicist worldview. Nature was considered in some way as a great living organism in which each part had a well-defined function within the whole. The cosmos was conceived as a hierarchically ordered whole, endowed with a unitary dynamism, like a living being. Although there was no shortage of thinkers who defended mechanistic and atomistic ideas, organicism was an image that prevailed for centuries. Aristotle is often presented as the leading exponent of this image, in which purpose occupied a central role. While the importance of the quantitative was not denied, the primacy was undoubtedly given to the qualitative, both from the point of view of nature and our knowledge view of it. And the cosmos was integrated into a metaphysical perspective in which divinity was the ultimate reason for order.

On the contrary, 17th century science emphasised the quantitative and the empirical in contrast to the Philosophy of the Aristotelians of the time. Mechanics, which was the first discipline to be constituted as a progressive system, was presented as the basic science of the physical world, and its growing success over the following centuries seemed to impose mechanicism as the true picture of nature. Everything was explained by laws governing the behaviour of portions of subject. The universe came to be regarded as a gigantic machine, and even man seemed to be understood by means of this model. Of course, the great pioneers of physics and many of their brilliant successors were people of deep religious convictions, but the inner logic of mechanicism favoured the spread of a materialism that claimed to be backed by the success of science.

The scientific revolutions that took place at the beginning of the 20th century revealed the inadequacies of mechanism in science, and provoked an avalanche of programs of study about the nature and scope of the scientific method. There is no unanimity in proposing what would be the appropriate picture of nature today. However, it can be considered as basically accepted that the contemporary worldview proposes a dynamic and processual picture of nature; that it stresses the constructive aspect of science, whose models are considered provisional and fallible; and that it seeks to synthesise the mechanistic and finalistic aspects through the notion of system.

Intelligibility and causality

Undoubtedly, the ancient organicist worldview has been superseded in many respects by later scientific advances. However, it included one that is essential for tackling the problem of the intelligibility of nature. I am referring to the typology of causality, that is, to the Aristotelian theory of the four causes.

The four causes of the Aristotelian Philosophy have, over the centuries, been of great interest in relation to the problem of intelligibility. Indeed, intelligibility refers to explanations, and in turn, explanations refer, to a large extent, to Aristotelian causes.

Material causality and formal causality place us before the problems that refer to the composition and conformation of natural beings. Efficient and final causality refer to the activity of these beings and the directionality of their activity. When we seek explanations of natural phenomena, we are asking ourselves about their causes.

This perspective seemed to go into crisis when modern science focused on the formulation of relationships between phenomena and their expression in laws. The philosophical approach gave way to a more phenomenal perspective. It could be thought that experimental science has nothing to do with the investigation of causes and would fit instead into phenomenist and positivist schemes. In particular, formal and final causes seemed doomed to disappear; they were even blamed for the scientific sterility of antiquity. In modern science there seemed to be room, at most, only for material and efficient causes, which, moreover, were translated into quantitative concepts such as mass and force.

However, progress in biology, where teleonomy plays an essential role, has contributed to rethinking the problems of finality. It has been noted that the discrediting of finality was due, on the one hand, to the exaltation of a mechanistic image which proved, in the end, incapable of explaining many phenomena, and, on the other hand, to the unscientific desire to combat a metaphysical and transcendent perspective. Even the advocates of materialistic ideas have had to admit that there are ends in nature. And it is possible to argue that this is not only true in the realm of the living. Indeed, quite a few laws of physics, such as the principles of maxima and minima, the laws of conservation, and the principles of symmetry, can be regarded as expressions of natural tendencies, which is tantamount to admitting finality.

This is closely related to formal causality. This too was anathematized in the name of a mechanistic Philosophy that reduced nature to the quantitative characteristics of subject, and science to the study of those characteristics. However, subsequent progress has led to the assertion that, if one essential feature of subject can be singled out, it is its tendency to produce patterns. From the minute level of particle physics, to the enormous conglomerates of astrophysics, to the complexity of living things, what we discover are Structures that integrate to produce new Structures, from agreement with laws that are becoming better and better known. The whole of science appears as an attempt to learn more about different levels of organisation which, in turn, are closely related to each other.

Undoubtedly, the application of the Aristotelian causal outline must be adapted to new knowledge. But it seems possible to affirm that nature will be intelligible to the extent that the explanatory categories represented by the four causes can be applied to it.

3. Scientific truth

But can we really apply the categories of causality to our study of nature? The picture offered by contemporary epistemology is disconcerting in this respect. Indeed, instrumentalist and relativist interpretations are widespread in contemporary epistemology, according to which one could not even talk about truth in science.

It is obvious that the problem of the intelligibility of nature is nowadays closely linked to the problem of scientific truth. To what extent we can say that nature is intelligible depends, to a large extent, on whether it can be argued that science provides true knowledge about nature. Otherwise, it would be difficult to argue that we can understand nature by means of explanatory categories. It is therefore necessary to look more closely at the problem of scientific truth.

According to instrumentalism, science provides only instruments or tools that are useful for the prediction of phenomena. According to relativism, different theories are framed within conceptual frameworks that depend on changing sociological factors and cannot be demonstrated. Both perspectives agree that experimental science only provides useful models that have little or nothing to do with truth. On the other hand, even realists tend to regard truth as a regulative ideal which, in the internship, would be unattainable, because any scientific theory must be subject to possible revisions.

I will argue that these interpretations extrapolate partial aspects of science, giving a picture of science that does not match reality.

Instrumentalism emphasises the predictive aspect of science, which is undoubtedly of great importance. Experimental science can be characterised as an activity in which we seek knowledge about nature that can be subjected to experimental control. Therefore, scientific statements, in order to be acceptable, must meet the minimum requirement of experimental control, i.e., it must be possible to use them to obtain predictions about natural phenomena. Moreover, predictive power is one of the basic criteria for the acceptability of theories, to the extent that a single novel prediction, provided it is sufficiently important and precise, is usually sufficient for a theory to be considered as seriously established.

However, this does not favour an instrumentalist interpretation. Rather, we can think that, if there are controllable predictions, it is a sign that we have reached an authentic knowledge about nature. The empirical adequacy of theories refers to a coincidence between scientific constructs and reality, and this coincidence only makes sense within a realist perspective.

The rationale of instrumentalism partly overlaps with that of relativism by stressing that experimental results can be explained by different hypotheses and that, therefore, the adequacy of theories with empirical data is not a sufficient test of the truth of our constructs. This is partly true. But there are criteria that add to the predictive power and sometimes allow us to state with sufficient certainty that our explanations are adequate.

One is explanatory power; for example, the double helix structure of DNA explains genetic phenomena in such a way that it must be accepted that this structure corresponds to reality. Other criteria are the accuracy of explanations and predictions, the range of independent evidence, and the mutual support of different theories when they overlap in common applications. When an explanation meets all these criteria, we can legitimately claim that it corresponds to reality. At final, while it is true that theories arise within a conceptual context that is not unambiguously determined by the empirical data , it is also true that we can prove, not infrequently, that we reach authentic knowledge.

Fallibilism insists on the insufficiency of logical proofs to definitively establish any theory. Fallibilism asserts that we cannot prove the truth of any theory and must therefore be content to detect errors and correct them; it concludes that the entire scientific knowledge is conjectural and revisable; and it rejects any claim to certainty, describing it as dogmatism that would paralyse progress.

Fallibilism is acceptable and even useful if it is interpreted as a partial methodology, that is, as a stimulus not to get bogged down in already known theories and to try to detect their limitations. But if it is considered as a philosophical interpretation, it easily becomes a source of confusion. Indeed, it would not even make sense to speak of error if we could never reach the truth. Moreover, admitting that the validity of any theory has limits does not mean that it must contain errors. And finally, fallibilism is not agreement with the certain fact that we get authentic explanations about reality.

In order to specify the notion of scientific truth, it is necessary to note that this truth is always contextual. Indeed, each theory is formulated within a specific point of view, defined by the use of concepts and instruments that do not exhaust all possible perspectives. For the same reason, scientific truth is partial. But, if it is well tested, it is an authentic truth. For a context to be well determined, the meanings and references of concepts must be well defined and, under these conditions, it is possible to formulate intersubjective proofs and to establish the correspondence between theoretical constructs and reality.

Of course, scientific statements are our constructs. They are not mere translations or representations of reality. They are formulated in a language that we construct in order to be able to dialogue with nature, which only speaks to us through facts. In order to engage in such a dialogue, concepts have to be constructed which, on the one hand, have to be defined theoretically by means of stipulations, and on the other hand, have to be related to the possible results of repeatable experiments. But the constructive aspect of science is not an obstacle to truth in science. On the contrary, it is what enables us to formulate intersubjective proofs that are rigorously related to the results of our experimental study of nature.

4. Science and realism

I will now go to fill in the above reflections by examining realism. I will argue that realism is a presupposition of science, and that scientific progress has a bearing on realism because it retro-justifies, specifies and enriches it.

Realism can be considered, on the epistemological level, as the affirmation that our knowledge reaches reality, and on the ontological level, as the affirmation that there is a natural order that has a consistency of its own. The above reflections on truth are situated at the epistemological level, and allow us to affirm that experimental science is a way to reach authentic knowledge about reality. I will now focus on ontological realism with the intention of showing that the natural order, as it manifests itself to us through the achievements of science, reflects the intelligibility of nature and is a privileged path for philosophical reflection about it.

The existence of a natural order is already assumed in the ordinary knowledge . Scientific truth also assumes that there is a natural order that provides the instructions to formulate laws and to control them by repeatable experiments. Therefore, the preceding reflections on scientific truth are also a test in favour of a realist ontology.

The idea of order includes two aspects: regularity and coherence. There are regularities at different levels, and coherence means that these levels are related and form a unitary whole. On the other hand, to say that order is natural means that it has a consistency of its own and therefore cannot be reduced to subjective characteristics such as the need to postulate regularities in order to formulate explanations.

Experimental science is based on the assumption that there is a natural order that extends to levels inaccessible to immediate inspection, and further assumes that we are capable of knowing that order. test In effect, the method of construction and control assumes that we can relate our explanatory theories to factual data , conduct experiments to test the theories, and correct them when they do not agree with the corresponding data . The effectiveness of this method sample that the existence of a natural order is not merely a regulative idea of research, but corresponds to the very structure of nature.

Anti-realist perspectives fail to account for the method used by experimental science and its achievements. Realism is a necessary condition for the existence and progress of experimental science, and since experimental science exists and progresses, we must also admit what is its necessary condition of possibility.

The heuristic capacity of realism is another argument in its favour. Positivism, relativism and instrumentalism will have to justify their rules by arguments independent of realist ontology, and this does not always seem to be possible; indeed, we seek to prove the existence of real entities, properties and processes, and we would not do so if we thought they were only useful instruments. The history of science is illustrative in this respect.

We can claim, therefore, that scientific progress retro-justifies science's realist assumptions about the existence of a natural order. Moreover, it can be shown that it clarifies and enriches them. Indeed, scientific achievements provide us with a detailed knowledge of the Structures of nature. This knowledge has enabled us to abandon many misconceptions about natural entities and processes, and to obtain a representation of them that is increasingly adequate to reality.

Experimental science is not simply an accumulation of scattered partial knowledge. It also provides us with an increasingly unified representation of nature. One of the main goals of science is to obtain unified theories and, in fact, it is easy to see that scientific progress is a path towards unification. The more science progresses, the more nature appears to us as an orderly structured reality.

Indeed, scientific constructs allow the unification of different aspects of nature. Particular empirical laws express regularities that unify different phenomena. General laws or principles unify different kinds of phenomena. Theories unify one or several fields of phenomena under some general laws or principles. History sample that scientific progress means progress towards unification. The first empirical laws that make it possible to construct a new discipline are later related by general laws that explain them, and further progress consists in constructing theories that provide unitary explanations of many previously scattered phenomena.

As already noted, one of the most remarkable achievements of science is the finding of patterns, so that the existence of progressively integrating patterns is perhaps the fundamental property of the subject. This should not be surprising, since subject only exists as structured under configurations or patterns. It is important to underline that scientific progress, by discovering more and more natural Structures and explaining how they are related and intertwined, confirms that the existence of natural order is an ontological assumption of science. All this sample that the progress of science retro-justifies, clarifies and expands our ideas about the real order of nature.

5. The systemic perspective

One of the characteristics of the natural order, as represented by modern scientific progress, is its systemic character. The mechanistic and organicist representations have been replaced by a systemic perspective that reconciles the valid aspects of both in a new synthesis.

The idea of system, as it is used in our time, emphasises that the whole is not a mere additive sum of its parts. Mechanism was accompanied by an analytical perspective according to which the knowledge of nature was obtained by breaking it down into its component parts and adding up their properties. Systems theory insists that such a representation is insufficient. The characteristics of a system are not obtained by simply meeting from the characteristics of its components. There are specific properties at each level that do not occur at lower levels, and these properties are produced as result of interactions that have a selective character.

Illustrative examples can be found at all levels. At the atomic level, quantum laws have a strongly selective character, and show that nature is governed by very specific patterns. At the chemical level, molecules owe their character to the component atoms, but also to the different Structures in which these atoms combine, so that the same atoms can give rise to different molecules. At the biochemical level, the specific Structures play an equally central role.

All this sample that nature possesses a highly specific order, governed by tendencies that are inscribed in the entities at all levels. The homogenous image favoured by mechanicism proves to be inadequate to account for the natural order.

This represents, in a way, a recovery of the organicist image. But it is an organicism that has undergone a profound treatment. Indeed, the recovery of the structural and finalist characteristics is now reconciled with the validity of the mechanistic image. It is not claimed that the Structures and the ends have an existence independent of the components, but that they are the result of their interactions.

But this coincides, to a large extent, with the basic ideas of the Aristotelian perspective, according to which independent existence corresponds only to natural substances, composed of form and subject. The form of natural entities does not have, in the Aristotelian perspective, an entity independent of the subject. The Aristotelian Philosophy also underlined the existence of an immanent finality, insofar as the ends represent the natural tendencies that result from the forms. Hence, as we pointed out at the beginning, we can speak of a recovery of Aristotelian causes as explanatory categories of nature.

6. The processual perspective

On the other hand, the synchronic picture about natural Structures is completed and explained by a diachronic picture that allows us to understand how natural patterns come into being and develop.

Certainly, our representations are incomplete. There are important gaps about morphogenesis or the production of new forms, and we do not have complete explanations about the connections between the different levels of nature. In this context, the problems of emergence and reduction are central.

Reductionism is presented as an attempt to explain higher levels by lower levels. Multiple attempts have been made to substantiate reduction between scientific theories. The difficulties of classical analyses, which treated reduction as a logical deduction of laws or theories, suggest that the problem of reduction should be replaced by that of relations between levels. Indeed, a reduction by logical derivation of some theories with respect to others rarely occurs, and there are even grounds for claiming that such a reduction is impossible. On the other hand, it seems possible to obtain, in some cases, a weak or instrumentalist reduction, but this would only amount to a partial and approximate coincidence of the results of different theories. In the real scientific research , what is in fact achieved is to establish partial connections between different levels.

Morphogenetic theories represent an attempt to explain how entities and processes at a certain level arise from entities and processes at lower levels. The possibility of formulating morphogenetic theories depends on the existence of a hierarchy of interrelated levels. But it is also conditioned by epistemological limits, since each level has its own manifestations and its study requires, consequently, the adoption of different perspectives that can hardly be reduced to a unity.

At the level of physics, we find different theories that, although they may be related in some way, continue to maintain their own value within the perspective that each of them assumes. Classical mechanics can be considered, in a way, as a limiting case of quantum and relativistic theories, but this does not prevent it from continuing to have its own scope of validity; it is not even easy to prove that it is a simple result of the other theories. It is doubtful that Chemistry can be reduced to physics, and even more doubtful that biology can be derived from Chemistry. At each level we find new features which, although they rely on the properties of the lower levels, are not reduced to them.

The difficulties are even greater if we do not limit ourselves to relating adjacent levels, but try to find valid explanations for more distant levels. This is the case for some morphogenetic theories such as non-linear thermodynamics, synergetics, catastrophe theory, and chaos theories.

Non-linear thermodynamics, or irreversible process thermodynamics, sample that biological processes are compatible with the second law of thermodynamics, and suggests that in open systems, far from equilibrium, biological Structures can be formed by the amplification of fluctuations leading to a new state in which dissipative Structures is maintained. This is of great interest from a morphogenetic point of view. However, here too, there is no mere logical reduction or elimination of the properties of the biological level.

Synergetics, or the science of cooperative actions, provides explanations for the emergence of new natural patterns from specific component situations. Catastrophe theory is a mathematical theory about the emergence of structural properties at very different levels. Chaos theories represent another attempt to explain, by new ways, how order emerges from natural patterns. In all these cases, there is often an attempt to relate very different natural and epistemological levels, which implies that it is difficult to rigorously establish the validity of the models proposed. The main interest of such morphogenetic theories lies in their heuristic value, as they suggest the existence of structural similarities at various levels and thus facilitate the research of the unitary characteristics of nature.

As already pointed out above, progress towards unification is one of the regulative principles of the scientific research , and is one of the main contributions of science to deepen our understanding of nature. What we have just said about morphogenetic theories sample that, however great the difficulties in achieving a unitary picture of nature may be, many valuable results have been achieved that give grounds to affirm again that scientific progress greatly enriches our ideas about the natural order.

7. The dynamism of nature

The systemic and processual characteristics of nature, described in the previous sections, lead us to affirm its dynamic character.

Already in the face of ordinary experience, nature manifests itself as a set of processes independent of our will, possessing a dynamism of its own. The old organicist worldview emphasised this aspect, even going so far as to assert the existence of a soul of the world. On the other hand, the modern mechanistic image emphasised the existence of laws, which, moreover, were conceived as deterministic relationships. Today's worldview, without losing the ground that scientific progress has gained, restores to nature the dynamism that is proper to it. And in this aspect too, we can take advantage of the virtualities contained in some classical explanatory categories.

This is the case of the Aristotelian notion of form. Mechanism discarded it, or at least gave it a quantitative meaning, identifying it with geometrical configurations. Today, we can better understand the potential of this concept, which refers to the modes of being of natural entities. When the philosophical tradition asserted that form gives being, it implied something that is not only legitimate, but must be recovered. Concretely, the notion of form reflects a basic intuition, namely that natural entities have an ontological consistency of their own, which is source of their dynamism.

Nature appears, today more than ever, as a source of dynamism. The Aristotelian idea that every substance possesses a nature which is its inner principle of activity is an important intuition. The more we are able to manipulate nature artificially, the more it becomes clear that our activity consists in directing the intrinsic dynamism of nature towards certain goals. Scientific progress increases the reasons for astonishment at the dynamism of nature at all levels.

The categories of the natural Philosophy are often interpreted in a static sense. It would be necessary to recover the dynamic sense they originally had. The concept of subject suggested, as its etymology itself indicates, that from which comes that which is produced by a process. The concept of nature is also related to the processes of birth. To understand nature as it really is, we need to formulate dynamic categories, or use traditional ones in such a way that they do not lead to static representations.

8. Physics and Philosophy

It is precisely the ontological consistency of nature, with its characteristic dynamism, that leads us to ask about its primary origin. The basic dilemma we are faced with is whether to accept a naturalism that considers nature as self-sufficient, or to recognise that we must admit the existence of dimensions that go beyond the level of nature and give reason for it.

In this context it is important to note that scientific progress by no means implies a naturalistic perspective. We have already pointed out that different scientific theories are constructed by adopting partial points of view. It should now be noted that experimental science as a whole presupposes the adoption of a point of view according to which only knowledge that can be related to experimental control is considered admissible. But this says nothing, either for or against, about the possibility of other perspectives.

When it is argued that experimental science supports naturalism, a scientistic approach is taken for granted, according to which experimental science would be the only valid way to know reality. But this approach is contradictory, since its very formulation falls outside the scientific realm and therefore, if the rule he himself establishes is applied to it, it should be discarded.

Scientism seems to find some support in the peculiar reliability of experimental science, which is presented as inter-subjective, empirically controllable, capable of leading to predictions, and progressive knowledge . However, a close examination of these characteristics sample shows that they are made possible by a voluntarily accepted limitation. Specifically, experimental science, by its very nature, can only refer to those aspects of reality that can be subjected to experimental control, i.e., to entities and processes that are in some way subject to given rules.

It might seem, then, that one should accept a Cartesian dualism of subject , in which nature is conceived in material, deterministic and quantitative terms, and spirit belongs to the realm of human subjectivity. Metaphysics would be limited to the study of typically human phenomena. In this perspective, there would be no place for a Philosophy of nature, since everything that could be said about nature would fall within the realm of experimental science.

However, the above reflections show that this interpretation is not satisfactory. Even a descriptive study of nature, if no arbitrary limits are imposed on it, leads to problems that can only be approached using philosophical categories. And if the ultimate questions are posed, the need for philosophical reasoning appears even more strongly.

In order to obtain a rigorous worldview it is necessary to integrate the knowledge that experimental science provides about nature. This implies an interpretative work in which philosophical categories will necessarily be used. The problem is to find the right categories.

9. Cosmological categories

Without claiming to exhaust topic, we will point out some characteristics that should be present for the philosophical study of nature to be rigorous and goal.

The first is the recognition of the limited scope of philosophical categories. One of the lessons of scientific progress is the need to specify the scope of our explanations. A rigorous Philosophy of nature will have to be aware of its limitations. It will not pretend to supplant the sciences on their own ground, and will use their categories without granting them a generality that goes beyond the real possibilities. Cosmological categories are only partially valid, for they will necessarily refer to partial perspectives on nature.

A second feature is the introduction of intermediate categories. Precisely because cosmological categories are only partially valid, we need some flexible conceptualisations, which can serve as a bridge between the various levels of nature. There is discontinuity between these levels, but there is also continuity. For example, while it is legitimate and even necessary to use dual concepts such as organic subject and inert subject , it should not be forgotten that these concepts are necessarily schematic. In reality, there is no such thing as a purely passive and inert subject , since subject, in any of its manifestations, is configured and has a dynamism which, precisely, is at the basis of the dynamism that occurs at higher levels.

A third characteristic, related to the two previous ones, is the awareness that these categories will have to include analogies and metaphors that are not always to be interpreted literally. Just as experimental science needs to construct idealised models, the natural Philosophy needs to resort to images that, while being faithful to the reality they express, allow us to interpret it in a way that is intelligible to us. The danger of anthropormorphism will always be present. The way to avoid it is not to try to eliminate any anthropomorphic connotation, but to be aware that anthropomorphism exists and that we need it to make reality intelligible. The use of models, analogies and metaphors is legitimate and, in fact, frequent in science itself; it is only necessary to demand that these figures be interpreted without losing sight of their function.

Fourthly, it is necessary to distinguish between descriptive and explanatory categories. The former are necessary to conceptualise reality, and among them are the concepts that serve to describe entities, properties and processes. The latter are necessary to formulate explanations of the described reality, and refer to principles and causes. The adequacy of explanatory categories will depend on the precision with which descriptive categories are formulated and the rigour of the corresponding logical tests.

10. Nature and transcendence

I will finally point out that the question of the intelligibility of nature, if taken to its ultimate consequences, leads to the problem of transcendence. This problem has been present since the beginnings of philosophical speculation, and continues to be posed in various ways at purpose of contemporary scientific developments. The discussions about the origin of the universe, the anthropic principle and finalism are sufficiently significant examples in this respect.

However, arguments about transcendence require an examination that goes beyond the possibilities of the Philosophy of nature, as they enter the realm of natural theology. Although nowadays it is common to refer to borderline questions between science and theology, it is not difficult to see that these are two different approaches and that there is therefore no real overlap between their problems; and something similar can be said about the relations between the Philosophy of nature and natural theology.

Of course, in the works on experimental science and on natural Philosophy one finds questions that are in some way related to the problems of natural theology. It is logical that those who encounter them should not leave them in the hands of other researchers. There is nothing to object to this, as long as, in dealing with these problems, the necessary logical rigour is used and unjustified extrapolations from one field to another are avoided.

The search for an integration between the different fields of explanation is always an important task, the interest of which is underlined in our time by the existence of a large specialization which makes it difficult to achieve unitary explanations. The Philosophy of nature can make an important contribution to this goal. Indeed, many obstacles to integration come from scientistic and naturalistic perspectives which, although objectively outdated and responding to positivist approaches that have been largely superseded by the very development of science and epistemology, are presented as if they were a consequence of scientific progress.

Epistemological analysis suffices to uncover the fallacies of such attempts. However, if a positive integration of different knowledge is to be achieved, it will be necessary to work at the level of the Philosophy of nature, which is the philosophical level at which scientific ideas must be evaluated in order to determine their full meaning.

I will conclude by pointing out that one of the most promising areas for achieving the integration of different kinds of knowledge is the study of the presuppositions of science. Precisely one of them is the intelligibility of nature. The scientist must assume that there is a natural order that is independent of his investigations, and the progress of science shows that this order not only exists, but that it is full of strength, vitality and unity.

A renewed Philosophy of nature is the indispensable bridge to descriptions and explanations which, taking into account the information provided by science and proceeding with all the necessary logical rigour, make it possible to achieve a genuine integration of the different fields of knowledge. A rigorous Philosophy of nature will present nature with all its own consistency, and at the same time refer to deeper explanations of this consistency, which can only be found in the field of natural theology.