Why Logic, Briefly Illustrated

It has occurred to me that some might question why, in my immediately previous post, the “The Inconsistency of the Doctrine of (the Distinction of Divine Persons and so That of) the Trinity with Monotheism” of April 4, 2014, I went to such logical lengths in demonstrating that the orthodox Christian Trinitarian doctrine is untenable. The reason is that, if we don’t go to such lengths, we can easily fall into elementary logical errors.

It happens even to the best of us, and not to just those of us who are among the rest of us. For example, as I rummaged this morning among some old handouts I wrote for some of the introductory philosophy courses I taught “back in the day,” I came across one documenting an argument offered by Owen Flanagan in his The Problem of the Soul: Two Visions of Mind and How to Reconcile Them (New York: Basic Books, 2002). First, though, the context of theoretical context of the argument is of some pertinence: Flanagan tells us (p. xiii) that:

[His] main aim is to show that the scientific image can give us pretty much everything we can sensibly want from the concept of a person. Most of what we traditionally believe about the nature of persons remains in place even without the unnecessary philosophical concepts of the soul and its accompanying suite.

Now then, the argument, as he presents it (Ibid., p. 3):

There are no such things as souls, or non-physical minds. If such things did exist, as perennial philosophy conceives them, science would be unable to explain persons. But there aren’t, so it can.

Restated, i.e., “regimented,” in the logicians’ jargon, so as to make its logical structure more immediately obvious, the argument is:

If there are such things as souls or non-physical minds, then science is unable to explain persons.

There are not such things as souls or non-physical minds.

Therefore, science is able to explain persons.

This, of course, is a garden-variety case of the logical error known as the fallacy of the denial of the antecedent. Even if the two premises are or were both true, it does or would not follow, in the absence of a further premise or two, that science is able to explain persons, for there might yet be further impediments.

The more evident fallaciousness of an exactly parallel argument might be helpful. Take:

If there are such things as seagulls, then beachgoers are unable to picnic safely.

There are not such things as seagulls.

Therefore, beachgoers are able to picnic safely.

There might yet be further impediments to safely picnicking at the beach; there may be hungry and aggressive pelicans around, for example.

Returning to souls, non-physical minds, and science, I am inclined to accept as sound the following perfectly valid argument, like all arguments of the form known as Modus Ponens, perfectly valid in that, if its premises are true, then its conclusion is also true:

If there are such things as souls or non-physical minds, then science is unable to explain persons.

There are such things as souls or non-physical minds.

Therefore, science is unable to explain persons.

Let me hasten to add that I am not at present able to categorically affirm that it is sound, i.e., not only that it is valid but also that its premises and its conclusion are all three true. In other words, I am unable to offer it as anything approaching a proof or demonstration.

Until next time.

About Rchard E. Hennessey

See above, "About the Author/Editor."
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4 Responses to Why Logic, Briefly Illustrated

  1. This is something I was always tempted with when given a form that looked like that. It’s obviously tempting, but wrong. A lot of fallacies are like that. My question is this, and it’s not exactly a philosophical question but, if fallacies like this are tempting and common, why do you think that logic is not taught more in schools? My high school taught it(and had it as a requirement. Admittedly it was just Aristotelean logic and not modal or categorical logic, but still.), but not many others in my area do. Would we benefit from reinstating it as a requirement, or not? Do you think it would help us to avoid these temptations?

  2. I do indeed think that logic should be taught in schools. Just how to go about it, though, is an open question. One possibility would be that of a separate course or set of courses. Another might be that of a program of “logic across the curriculum,” by analogy with “writing across the curriculum” and “reading across the curriculum.” Or, the “logic across the curriculum” program might well be part of a “critical thinking across the curriculum,” assuming one draws a line between logic and critical thinking and assuming that the whole is set up intelligently. The thought is that logic and thinking are more fundamental than reading and writing.

    All students, just in the interests of good citizenship, should understand the the elements of both propositional and syllogistic logic. But informal logic is also necessary. We all too often, for example, hear or read people making statements like, “Americans believe that…,” or “Liberals hold that…,” or “Conservatives hold that…,” with no hint of a recognition that such statements are, if not implicitly universal statements, likely to be taken as such. And there are very few things that all Americans believe or that all liberals or conservatives hold.

    • That’s an interesting thought that reading and writing are less fundamental than logic and thinking. You don’t usually hear that. It’s true though even though they are interconnected. There were arguments among Baghdadi philosophers (Abu Sa’id al-Sirafi and Abu Bishr Matta) in the Medieval world about which was more important Logic or Grammar.

      And I think it’s both. Formal and Informal logic and how to construct arguments are just as important as how to construct a sentence. A nonsense sentence isn’t really a sentence after all.

  3. To put it way too simply, it seems to me that we need to distinguish between logic, if we take the the term to refer to the art and science of effective reasoning, and philosophical grammar or linguistics, if we take that to be the art and science of effective communication, And then put them back in relation.

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