Home » John Deely on the “Practical Value” of Logic

Peirce rightly speaks of the practice of boasting of the utility of this or that science as a “nauseating custom” (1898a, alt. ver. : CP 1.667). This is because the practice in question almost invariably is indulged in for purposes quite unrelated to the true character of the science in question or to the advance of scientific inquiry as such. Nonetheless, there is a legitimate general sense in which all the sciences, logic and ethics included, may be said to have a practical value, inasmuch as, in the light of understanding gained from any given inquiry, application of that understanding may be made to meliorate some state of affairs or other. It is essential, however, to notice that this general “practical value” is a consequence of theoretical understanding, and not something separate from or independent of a properly scientific—that is to say, thematic and systematized—study of, for example, the symbolic structures of thought, on the one hand (in the case of logic) and action, its motives and consequences, on the other (in the case of ethics). No doubt our practice of discourse will be influenced by a study of logic, and, if the study is sound, improved. But to aim at this improvement directly and from the outset is a fundamental blunder. It is no wonder that many courses in “critical thinking” amount to little more than an elaborate spelling out of the steps to go through m choosing the best refrigerator to buy for your home, or a hopelessly superficial skill in identifying and labeling “fallacies”. For this reason, one of the most notable students of logic (Joseph 1916: 10) went so far as to recommend that we abandon speaking of logic as an art, in order to make plain what is in fact the case: that any properly human practical value of logic is in consequence of its theoretical study, and not an end that can be attained directly. In this sense, any scientific study has a “practical value”.

But, while any scientific study has practical value in an indirect sense, the practical value of logic, even if indirect, goes beyond that of the other special sciences, and precisely for this reason logic is commonly viewed not just as a “general education” requirement, but as a “core requirement”—that is to say, as one of the foundations of liberal arts education even from the days when science in our modern sense had not yet been established or envisioned as part of the curriculum of schooling at any level. In other words, uniquely in the case of the science of logic, we are quite justified in speaking of its utility or “practical value” for reasons that are related both to the nature of logic as a science and to the advance of logic as a scientific inquiry.

The exceptional extent of logic’s indirect practicality becomes apparent in Joseph’s spelling out (ibid: 11) of the threefold rationale for the practical value of logic. Of the three elements he identifies in this rationale, the first logic shares with any science, as we have taken note. The remaining two, however, distinguish logic’s foundational character as permeating the humanities and the sciences alike—that is to say, the whole of our discourse.

The first practical value of logic in general education, the one it shares with any exact science, is that it demands a careful, systematic and precise treatment of its own subject matter, which tends to produce a habit resulting from an appreciative understanding of the need and importance of carefulness in the study of any subject.

The second practical value of logic, however, lies in an effect which the study of a special science like chemistry, physics, or biology, is not equally calculated to produce. This effect is a better realization of what general forms are latent in the language we habitually use (especially where it is a question of our natural language, hut also in specialized and “artificial” circumstances of discourses which… inevitably interface with and influence the prejacent natural language, ensuring its continual evolution, in fact, and expansion into new scientific fields), through becoming familiar with the task of examining our reasonings precisely to see whether their form is conclusive in itself in its contrast with the factual content.

The third practical value of logic is likewise commensurate with our discourse in its totality, whether everyday or scientific, theoretically or practically oriented: logic requires us to deal directly with what knowing is, insofar as there are standards implicit in thought itself by which it is possible to separate knowledge from opinion and also to distinguish levels or grades of both, thereby making us more alive and sensitive to, as well as more careful about, shortcomings in our own opinions and those others try to persuade us of.

I think we need not go as far as Joseph recommended in abandoning all talk of logic as an art in order to appreciate the difference between logica docens and logica utens and to appreciate the essential dependency of the latter on the former as far as it concerns an educational context beyond the exercise of practical reason. It is true that the theoretical study of logic not only can be but, in recent years, has been entirely divorced from the context of actual discourse in common experience. But this need not he the case (nor is it wholly new), and may even be regarded, in many instances, as a pedagogical aberration. Nor does the late modern artificialization of the context of logical study change the fact that there are indirect consequences of logical study for everyday discourse when the foundations of such study are properly established (a project toward which this book is mainly aimed). These consequences are nonetheless real, and become direct from the side of the theoretical understanding once acquired. There is nothing wrong with pursuing the theoretical study in such a way as to facilitate that indirect consequence, that overflow, as it were, into practical reasonings, and much to recommend such a pursuit, however much late modernity chose to eschew it. Indeed, what has always distinguished logic as a liberal art from logic developed as a science in its own right, without any regard for its connections with daily discourse, is just this way of pursuing properly logical study.

John Deely 1985–2015: Logic as a Liberal Art, 12–15 (not to be confused with Houser’s Logic as a Liberal Art).

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