COMMON SENSE. — The expression has two principal meanings in philosophy, one psychological and the other epistemological. In psychology, common sense is the internal sense that effects the unification and discrimination of external sensations and their objects. In epistemology, in its historically dominant acceptance (Reid and his school), it is the original and universal faculty of the human spirit to apprehend and formulate, prior to philosophical reflection, necessary or evident truths, whether of fact or of principle. From this historical epistemological meaning there have derived parallel current usages: common sense as the complex of fundamental principles or truths of reason; and common sense as the natural faculty, common to every normal person, of sound theoretical-practical judgment.
I. PSYCHOLOGY
The theory of common sense as a central faculty of sensibility received its definitive formulation only in medieval Scholasticism: it is understood there as the first of the internal senses, which, from both subjective and objective standpoints, effects the unity of the various sensations: “sensus communis est quaedam facultas ad quam terminantur immutationes omnium sensuum” (St Thomas, In II De an., lect. 13, n. 390; cf. Sum. Theol., 1ª, q. 78, a. 4 ad 1). Common sense thus functions, within the realm of sensibility, as the synthetic principle, in the unity of consciousness, of the manifold data of sensations and likewise of the sensory functions themselves: “a quo etiam perciperantur actiones sensuum, sicut cum aliquis videt se videre” (ibid., ad 2; cf. In III De an., lect. 3). In Aristotelian texts, however, the theory of common sense is not free from ambiguities. Based on a passage in De an., III, 1, 425 a 27: “of the (sensible) common we have a common sensation” (τὰ δὲ κοινῶν γὰρ ἔχουμεν αἴσθησιν κοινήν), Albert the Great and, more recently, Zeller, Baeumker, Ross, Cassirer, and De Corte held that in Aristotle common sense is the perceptual faculty of the common sensibles (size, shape, motion, etc.; Sertillanges [St Thomas d'Aquin, II, 4th ed., Paris 1925] and others attributed the same doctrine to St Thomas, but on the basis of a text from the spurious opuscule De potentiis animae). Against the exegesis of Albert the Great and Zeller are Trendelenburg, Brentano, and Waddington (cf. the thorough exposition and discussion in C. Fabro, Percezione e pensiero, Milan 1941, pp. 60 ff.: the Thomistic interpretation is there demonstrated—besides from the Summa Theol., II-II, q. 455 a 12, where the expression κοινὴ αἴσθησις seems to have the same meaning as the “sensus communis” of St Thomas—by the fundamental Aristotelian principle that the common sensibles are objects “per se” of more than one sense and not of a sixth sense). The medieval meaning of common sense was already present in St Augustine, who in De lib. arb., II, cap. 3 speaks of the “sensus interior” which “omnibus [sensibus externis] communiter praeest.”Later (Campanella, the Suárezian school, Mercier, Fröbes, etc.) the existence of common sense as a special faculty distinct from the individual external senses was contested, on the grounds that the awareness of seeing, hearing, etc., as immediate and of consciousness is a modality inherent in the sensory act itself, and when reflective consciousness is involved, belongs to higher spiritual functions. Already Aristotle seems to affirm that every sense perceives its own act (De an., II, 425 b 15; cf. Met., XI, 9, 1074 b 35: intellect and sense can, as it were, “supervene” to apprehend themselves). Modern psychology admits that the synthetic unity of the various sensory functions finds its explanation in the fundamental unity of consciousness and in the centrality of the physiological processes that condition II. The “cénesthésie” of modern terminology, which rather denotes the fundamental tactile sensibility by which one becomes aware of one’s own body and its functions and general biological conditions, must not, however, be confused with common sense in the medieval sense.
II. EPISTEMOLOGY
In its epistemological sense, common sense has had fundamental importance in Th. Reid (q.v.) and his school. For Reid, who opposed Hume’s empiricism and Berkeley’s immaterialism, the fundamental principles of all reasoning and science are in a certain sense innate to the mind; they are connected with perception, which is not the apprehension of “ideas” (against Berkeley), but intuitive knowing and the immediate presence of the object: “The most immediate conclusions which reason draws from perception form common sense; the more remote ones form science” (Inquiry, ch. 6, sec. 20). Common sense is thus the essential capacity of the spirit, prior to its reflective-scientific moment, to formulate universal and necessary propositions, and hence as the very principle of theoretical truth. Its maxims are those which prudent men follow in practice and life, and at the same time the original principles by which truth is distinguished from falsehood, without which certainty is impossible. It underlies the universal consensus (q.v.) of every human consciousness on first theoretical-practical truths. This doctrine, whose origins can be traced to the κοινὴ αἴσθησις of the Stoics (the motif was emphasized by Cicero: cf. De nat. deor., I, 17 and De orat., I, 3; De leg., I, 10), had already found a partial analogous expression in Shaftesbury’s “taste” or “moral and aesthetic sense” (q.v.) and was developed by the continuators of the Scottish school (J. Oswald, Appeal to common sense in behalf of religion [1766]; D. Stewart, Elements of the philosophy of human mind [1792]; Th. Brown, Lectures on the philosophy of human mind [1920]; A. Fergusson; later, with the inclusion of conflicting Kantian motifs, W. Hamilton); opposition to it constitutes, on the other hand, one of the fundamental, perhaps the most fundamental, tenets of Mill’s thought (q.V. MILL STUART J.). The meaning, if not the term, of common sense is, moreover, in a certain sense, implicit in all specific forms of rationalism (q.v.—Plato, Plotinus, Descartes). For Leibniz (q.v.), from common sense “c'est-à-dire de l'esprit même” come the ideas of space, extension, figure, motion..., the Aristotelian common sensibles (cf. Nouveaux essais..., II, ch. 5). Kant (q.v.) speaks of common sense as the presupposition of universally valid aesthetic judgments: it is to be understood as a “common feeling”: not a special sense, “but merely the effect of the free play of our cognitive faculties” (Kritik der Urteilskraft, part 1, sect. 1, I, 1, §§ 20–22; Italian trans., Bari 1938, pp. 79–82). F. Lamennais (q.v.) elevated common sense to the sole criterion of certainty, as the expression of general and common reason.In Neoscholasticism, common sense has generally been received in a positive sense, with a meaning analogous to that of Reid, though less systematic: “sens commun ou intelligence naturelle,” “la raison spontanée et primitive” (R. Garrigou-Lagrange, op. cit. in bibl., p. 1, 15): it would thus denote the natural way of thinking and judging of the human spirit, to which there corresponds, on the theoretical plane, “that natural and objective realism... which is, one might say, as Bergson expresses it, ‘the natural metaphysics of the human intelligence’” (ibid., pp. 18–19). It is in this sense, roughly speaking, that Aristotelian-Scholastic metaphysics is sometimes qualified as “the philosophy of common sense.”
BIBL.:
S. Tommaso, Summa Theol., 1ª, q. 78, a. 4; In II De an., lect. 13, n. 390; In III De an., lect. 3.
Aristotele, De an., II, 425 b 15; III, 1, 425 a 27; Met., XI, 9, 1074 b 35.
S. Agostino, De lib. arb., II, cap. 3.
C. Fabro, Percezione e pensiero, Milano 1941.
Th. Reid, Inquiry into the Human Mind, ch. 6, sec. 20.
D. Stewart, Elements of the philosophy of human mind, Edimburgo 1792.
W. Hamilton, Lectures on Metaphysics, Londra 1859–60.
R. Garrigou-Lagrange, Le sens du mystère et le clair-obscur intellectuel, Parigi 1934.
B. Croce, La filosofia di Reid, Bari 1913.
G. de Ruggiero, Storia della filosofia, parte 3ª, Bari 1947.
An objective assessment cannot fail to recognize in the universality and determinacy of thought a positive significance for so-called common sense. Already Heraclitus (q.v.) affirmed: “thought is common to all” (Diels, frg. 113; cf. Mullach, I, p. 322). There is at least one notion, the concept of being-non-being, which lies at the very essence of thought and universally underpins the first principles of every human discourse. These principles, though they do not in themselves constitute elements of a systematic metaphysical conception of being and nature, nonetheless form the basis of every attempt that reflective thought may undertake toward that end. If, however, by common sense one intends the more or less extensive complex of ideas, opinions, and even principles universally accepted by a given historical epoch, its claim to truth remains in itself problematic. In this sense, common sense is indeed, at least in part, a function of customs, culture, civilization, and history; nor are its universality and necessity fixed, since it receives and slowly assimilates, transforming them more or less, new ideas, conceptions, and systems. Thus understood, common sense cannot, from a theoretical standpoint, lay claim to unconditional authority, and its significance must be clarified by reflective thought, which determines its foundations, conditions, and causes.