The ordinary dualism of matter and mind. Sense-impressions and perception. Power of prediction of their course. Inferential knowledge of other percipients. Intersubjective communication. Formation of common knowledge. Defects of language and other forms of symbolism. Natural Science as a purposive continuation of common knowledge of percepts. The classificatory stage. Element of arbitrariness in it. Formation of concepts as symbols for percepts. Rules or Laws. Laws of Nature. Their mode of construction. Natural Science and the element of fact. Natural laws as characterized by Mach and Boltzmann. The construction of scientific laws. Discernment of order in percepts. Abstraction of individual differences Classification. Development of scientific principles and theories. Judgment of value of a scientific theory. Degrees of abstraction in scientific theories. Different species of concepts. Danger of overweighing theories with concepts. Irreducible concepts. Degree of abstraction does not cause generic differences between theories. Case of Geometry. View of scientific theories as conceptual schemes. Science as public knowledge. Limitations of scope of a scientific theory. Sciences which deal with the remote past. Approximativeness of actual measurements. Quantitative theories. Limited range of descriptive power of a theory. Statements as regards the whole Universe inadmissible. Possibility of all-embracing conceptual scheme need not be assumed. The notion of efficient causation unnecessary to Science. Approximately isolated systems. Conditions of success of a conceptual scheme. Tests of applicability of a scheme. Truth and falsehood of a scientific theory. Diversity of modes of application of a theory. Characteristics of Pure Mathematics.

Influence of philosophical views on scientific thought. Relation of Natural Science with systems of Metaphysical Philosophy. Neutral attitude of Natural Science as regards Philosophical and Psychological matters. Material objects. The notion of substance. Locke's description of it. Primary and secondary qualities of matter. Berkeley's idealistic position. Natural Science incapable of deciding questions of reality. Views of Poincaré and Whitehead. Views of Lodge on the Einstein theory. The dualism of the psychical and the physical. Assumptions of realistic Philosophers. Natural Science independent of ontological hypotheses. Indispensability of Philosophical Thought. Services of Philosophy to Natural Science. Poincaré's view of the relation of facts to Science. The psychical domain. The relations of the psychical with the physical. Psycho-physical parallelism. Theories of interaction. Limitation of Natural Science in respect to a complete Philosophy of Nature. Psychology. Difference between Psychology and Natural Science as regards subject-matter and methods. Partial similarity of Psychology and the Politico-social sciences with Natural Science.

The notion of causation. Efficient causation. Hume on efficient causation. The notion of efficient causation discarded by Natural Science as not to be discovered in phenomena. Cause as totality of conditions. Helmholtz's formulation. Continuity of processes. Logical necessity exists in thought not in phenomena. Explanation in the strict sense is not the function of Natural Science. The asymmetric relation of causation. Deterministic schemes of the most general type. Teleological conceptions. The notion of efficiency is not necessarily illusory. Biological Science and efficiency. Purposiveness. Natural Science in relation to prediction. The precise meaning of a deterministic scheme. Extensive magnitudes. Characterization of the state of a conceptual system. Representation of the states of a system by a set of functions. Does anything perceptual correspond to an ideal deterministic scheme? Limitations on representation by deterministic schemes. Difficulty of attaching a meaning to deterministic psychical schemes. That the whole world of physical phenomena is capable of representation by a unified deterministic scheme is unproved.

Arithmetic as a department of Natural Science. Arithmetical knowledge of the individual and the race. Pervasiveness of the concepts of Arithmetic. Arithmetic as a language. The concepts of unity and of number. The notion of order. Cardinal and ordinal numbers. Scheme of arithmetical operations. Fractions. Exactness of process of counting. The importance of notation in Arithmetic. The arithmetic of the Egyptians Babylonians and Greeks. Indian invention of negative numbers. The inadequacy of rational numbers for the complete representation of magnitudes. The modern theory of real number. Adequacy of real numbers for the representation of magnitudes. Necessity of the employment of irrational numbers. Extension of the conception of number to imaginary numbers. The infinite and the infinitesimal. The conception of a limit. The necessity of contemplation of the infinite. Cantor's theory of the numerically infinite.

The individual intuitions of time and space. Public time and its measurement. Abstract or absolute time. Time in abstract Dynamics. Newton's conception of absolute time. Individual spatial perception. Private space and geometrical space. Physical space as a construction. Conceptual space and Geometry. The development of Geometry. Euclidean Geometry. The theory of parallels. The Geometry of Bolyai and Lobachewsky. Descartes' introduction of analytical Geometry. Projective Geometry. Non-Euclidean Geometries. The theories of Riemann and Helmholtz. Riemann and the curvature of space. The application of Geometry to physical space. Criteria of applicability. Kant's view of space.

Two divergent views of the constitution of matter. The parentage of atomic theories. The cosmology of Democritus. The physics of Epicurus. The atomism of de Cusa and the cosmology of Giordano Bruno. Descartes' mechanistic view of the world. Disintegration of the Aristotelian conceptions. Gassendi's views. The materialism of Hobbes. Boyle's theories. The rise of the notion of action at a distance in connection with Newton's theory of gravitation. The gravitational theory of Le Sage. Newton's law as a genuine scientific scheme. Dalton's conceptions of chemical action and of atoms. Avogadro's molecular theory. Realistic and other views of atomic theories. Question as to the elasticity of atoms. The views of Secchi. Boscowitch's theory of atoms without extension. Kelvin's theory of vortex atoms. The kinetic theory of gases. General survey of the ideas which have inspired atomists. Change in atomism due to conception of forces acting at a distance.

The nature of a dynamical scheme. Classical Mechanics. Galileo's investigation of the law of a falling body. The contribution of Huygens to Dynamical Science. The Dynamics of Newton; his Regulae Philosophandi. Newton's conceptions of absolute space and of motion. The frame of reference in abstract Dynamics. The relativity of motion. The choice of frames of reference. The principle of inertia. Connection of relativity of motion with inertia. Circular motion regarded as a natural motion. Conservation of velocity in a straight line. A priori proofs of the principle of inertia by Kant and Maxwell. Notion of the body Alpha. The principle of inertia is not an a priori principle but in the conceptual scheme appears as a definition. The general conception of force. Contact-action is insufficiently explained. Action at a distance. Newton's measure of force. The laws of motion. Central forces. The extension of Newtonian Dynamics. Newtonian axes or inertial frames. The question of absolute rotation. Absolute directions cannot be determined in physical space.

The general notion of conservation. Difficulty as regards the precise meaning of the conservation of matter. The conservation of weight. The conservation of mass. The establishment of the principle of conservation of mass as the result of a gradual evolution. The medieval views. The views of Descartes as to conservation of matter. The views of Newton Huygens Boyle and Diderot. Chemistry and the conservation of matter. Lavoisier's investigations. The modern origin of the principle of the Conservation of Energy. The notion of work. The principle as conceived by Descartes Leibniz and Huygens. Conception of heat as a substance. The transformation of motion into heat. Experiments of Rumford and Davy. Views of Séguin and Sadi Carnot. Joule's experimental researches. Mayer and Colding on the conservation of energy. Extension of the scope of the principle by Helmholtz. Kinetic and potential energy. The reduction of potential energy to kinetic energy. Perpetual motion. The various forms of energy. Poincaré on the difficulty of defining uniquely the energy of a system. The principles of Energetics. Limitations of scope of the principle.

The aim of a mechanical theory. The ether as employed in mechanical theories. The realistic conception of an ether. Conceptual schemes and representation to the sensuous imagination. Force not an independent concept in Newtonian Dynamics. The department of Statics employs force as an independent concept. The later developments of Dynamics. Inexorable constraints. The deduction of d'Alembert's principle. Lagrange's analytical Dynamics. Modifications of Lagrange's scheme. The development by Sir W. Hamilton. The Hamiltonian principle. The scope of the principle. Irreversible systems. Helmholtz's cyclical systems. The earlier theories of Heat as caloric. The theory of Heat as motion. Carnot's investigations. Thermodynamics as developed by Rankine Clausius and Kelvin. The conception of entropy. The principle of increase of entropy or dissipation of energy. Restriction by Kelvin to non-living agencies. Willard Gibbs. Free and bound energy. Doubts of the adequacy of theories which only contemplate continuous transformations of energy. Planck's theory.

Triviality of the earliest known facts. Characteristics of various theories. Discovery of polarity of magnets. The researches of William Gilbert. Descartes' theory of Magnetism. Discovery of conduction of electricity. Discovery of two species of electricity. The Leyden jar. Theory of electric fluid. Induction. The law of electric force. The researches of Cavendish and Michell. Coulomb's electrical and magnetic measurements. Poisson's mathematical theories. The discoveries of Galvani and Volta. Discovery of electrolysis. Theory of the voltaic pile. Discovery of Oersted that a current is a magnet. Ampére's experiments and theory. Theories of ponderomotive forces. Faraday's researches. Connection with optical phenomena. Electrical energy in a circuit. The researches of Maxwell. Theories of light. Theories of luminiferous ether. Electromagnetic theory of light.

Irreducibility of the chemical elements. Atomic weights of chemical elements. Prout's ideas. Newlands' law of Octaves. Mendeléeff's periodic law. Crookes' theory of the genesis of the elements. The electron theory of matter. The cathode rays. Discovery of radio-activity. The source of energy in radioactivity. Discovery of helium. Rays emitted by radio-active substances. Emanations. Transmutation theory of radio-activity. Models of the atom. Artificial excitation of disintegration. Radio-active minerals as geological clocks. The existence of isotopes. Matter as built up of electrons and nuclei.

Nature of cosmical theories. Description of the solar system. Bode's law. Discovery of asteroids. Discovery of Neptune. Kant's speculations. Laplace's Nebular Hypothesis. Solar radiation. The meteoric theory. Objections to the nebular theory. Tidal action between the earth and the moon. Generation of satellites. Binary systems. The generation of double stars. The generation of stars from nebulae. The Doppler effect and the motion of nebulae. Primitive nebulae. The classification of stars according to spectral type. Radio-active substances as sources of heat. The age of the earth. General remarks on cosmical theories.

General remarks on the theory. Question as to the position of the theory in relation to Philosophy. General character of the theory. Comparison with Newton's theory. The measurement of space and time. Interdependence of spatial and temporal measurements. Gravitational phenomena and light. The metric of abstract Geometry. The spatio-temporal metric in a gravitational field. The special theory of relativity. Motion relatively to the ether. Experiments of Michelson and Morlcy. Postulates of the special theory. Replacement of the Newtonian Dynamics. Change in the conceptions of measurement. The four-fold ordered manifold or the “world” of Minkowski. The general principle of relativity and the theory of gravitational fields. Indefiniteness of Newton's law. The principle of equivalence. Identity of gravitational and inertial mass. Einstein's metrical theory as developed from Riemann's geometrical theory. The world-line of a material particle. The motion of the Perihelion of Mercury's orbit. Deviation of rays of light in the sun's gravitational field. Displacement of spectral lines. General remarks on the origin of the theory.

The concept of a living organism. Scientific definition of living organism and criteria of distinction between animals and plants. Method and limitations of Biological Science. The character of the concepts employed. Restriction of Physiology to physico-chemical processes and categories. Psychical and Psychological categories in Biology. The methods of Psychology. Science and the individual. The relation between the psychical and physical aspects of an organism. Methodological dualism necessary in Biological Science. Vitalistic ideas. The notion of guidance. Metabolism and mechanical processes from the point of view of Energetics. Conservation of energy in the organism. Comparison with a steam-engine. Transformation of energy in the cells of the leaves of plants. The law of entropy and the living organism. Driesch's theory of entelechy. Loeb's theory of tropisms. Psycho-physics or Physiological Psychology. The theory of specific energies. The investigations of Fechner and others. Comparison with inorganic Science.

Division into the two departments of Morphology and Physiology. Their characteristics. The biological work of Aristotle. His teleological view. Galen's physiological knowledge. The period initiated by Harvey. The systematization by von Haller. The origination of mechanistic theories of Physiology by Descartes. Vitalism in the eighteenth century. The Systematics of Linnaeus. The rise of Histology. The discoveries of Malpighi. The biological studies of the eighteenth century. The conception of a scale of beings. The views of Bichat on animal and plant life. Cuvier's views of the harmony of structure and function. Cuvier's division of the animal kingdom into types. The single type of Saint-Hilaire. The Philosophy of Nature. The law of parallelism. The views of Richard Owen. Embryology in the hands of von Baer. His theory of germ-layers. Von Baer on recapitulation. The cell-theory of Schwann. Criticisms of the cell-theory.

Abiogenesis and its refutation. The origin of life on the earth. The meaning of the term heredity. Aim of theories of heredity. The concepts of theories of heredity. Germ-cells. The embryo. Preformationist theories. Epigenesis. Theories of Pangenesis. Criticism by Weismann of Darwin's theory of Pangenesis. Weismann's theory of inheritance. The value of Weismann's theory. Criticisms of it. The inheritance of acquired characters. Statistical theories of heredity. The investigations of Galton. Galton's law of ancestral inheritance. The investigations of Mendel and his successors.

Notions of evolution of Aristotle and other Greek thinkers. St Augustine and freedom of scientific thought. Evolutionary speculations after the Renaissance. The evolutionary views of Buffon. The views of Linnaeus Cuvier and other naturalists. The evolution theory of Lamarck. The period before Darwin. The inception of Darwin's theory of descent. The effect of the publication of Darwin's views. The arguments of Darwin. The theory of Natural Selection. The anti-teleological tendency of the theory of Natural Selection. The evidence for the theory. The effect of environment. Mental factors in evolution. The views of Neo-Darwinians and Neo-Lamarckians. The theory of histonal competition. Weismann's views on evolution. Germinal selection. Discontinuous variations. The theory of De Vries.

The position of Natural Science as regards general theories of existence and reality. Natural Science circumscribed in its aim and restricted by its method. The conceptual knowledge represented by Psychology and Logic. Natural Science Psychology and Sociology are concerned with classes not individuals. The individuality of human beings. The principle of order and the principle of individuality. Knowledge obtained by the statistical method. Knowledge obtained by direct intuition. Cognition must be supplemented by other elements of human experience. The main characteristics of Religion Philosophy Science and Art. The notion of values. Conservation of values connected with existential elements. The relations between Religion and Philosophy. Theistic forms of Religion. Theism. The relation between Science and Religion is indirect through Philosophy. Any acceptable view of reality must not be incompatible with the existence of autonomous Natural Science. Essential characteristics of Philosophical systems. The case of solipsism. The element in the complex of percepts that is independent of the individual mind. Effect of assumptions as to reality.

Lord Gifford's description of the aims of his Lectureships. The practical influence of Natural Science on theistic belief. Theistic Philosophy. Theories of reality and the origin of phenomena. The relations of God with the world. Pantheism. God as transcendental. Intermediate theistic conceptions. Idealism. The One and the Many. The ontological proof. The distinction between revealed and other knowledge. The three traditional proofs. The cosmological proof. The correlation of reality with rational schemes. Miracles. The teleological argument. The moral argument for theism. The existence of physical evil. Limitations of the discussion. The practical relations between Philosophical Theology and Natural Science. Conclusion.