Aristotle’s Theory of Vision, or: Why Logic Matters!

To celebrate World Logic Day, I thought to write a public-facing explanation of why logic matters (and why I do research in it!). There are some instrumental reasons why logic matters: we quite directly owe, to research in logic, our computers and cell phones. In addition, I have often used a nice analogy with Aristotle’s theory of vision to explain why logic matters.

Aristotle held that one sees colors only when a transparent medium was activated by the present of light. This was natural enough, since we cannot see well in the dark. Philosophical insights are like colors, and logic is like light: symbolism in formal logic illuminates a whole array of philosophical ideas and novel suggestions that we otherwise would have been literally in the dark about.

This is the field of *philosophical logic*: the part of logic that is concerned with symbolizing various hypothesis, theories, experiments, and so on. Still, logic can often illuminate through a muddy medium: we can look at a philosophical problem through logic and see but a distorted picture of it, as when we look at something through water.

This is the field of *philosophy of logic*: the part of logic (and philosophy!) that is concerned with what logic is about, whether only one logic is in some unrestricted sense *correct*.

Both of these areas are part of my academic work, and both are naturally visible on analogy with Aristotle’s theory of vision. Happy Logic Day!

*Sources and further reading.* The philosophical logic versus philosophy of logic distinction is explained in Burgess’ *Philosophical Logic*, which is a fantastic book. Susan Haack’s book *Philosophy of Logics* treats philosophy of logic in greater detail and depth, and also belongs on your shelf. Aristotle’s theory of vision is presented in *De Anima* and the *Parva Naturalia*.

Against Huemer’s “Against History”

In a recent post at Fake Noûs, Michael Huemer asks why we have history of philosophy as a specific field of academic research. In Section 1, Huemer agrees that reading the works of dead philosophers is important and worthwhile. It is agreed that dead philosophers’ works are usually mined for the sake of creating a formulation of a problem. When this is done by a philosopher of sufficient disciplinary influence, and their work gets enough uptake among other philosophers, this formulation can become canonical and set the agenda for a subset of living philosophers.

What Huemer’s account omits is that this practice is part of the problem that historians of philosophy are trying to fix: the read-it-and-see-what-you-make-of-it way of interpreting a dead author can physically be done, I admit, by a reasonably good philosopher who is not a historian of philosophy. I agree that this sort of reading can result in interesting work. But Huemer already says this person, being a philosopher, is nonetheless probably wrong about almost everything. And a decidedly “ahistorical” philosopher who reads dead authors and then canonizes (to the misfortune of others) what they think was meant is probably also a very bad historian of philosophy.

If that is the standard for a canonical formulation of a contemporary problem, then why on Earth wouldn’t we want some historians to set such misreadings aright? It seems that Huemer’s methodology in history of philosophy naïvely sets us up to continuously get the dead philosopher wrong, then to have some other contemporary lumber along and give another interesting but incorrect misreading that then sets us up for another few years or decades of spilled ink over philosophical confusions that, for all the “ahistorical” philosophers know, were already identified and avoided by the dead philosopher they are reading.

Huemer asks four rhetorical questions:

[1] What are these scholars trying to find out? [2] Are they looking for more writings that have been lost or forgotten? [3] Are they trying to trace the historical roots of particular ideas and how they developed over the ages? [4] Or are they perhaps trying to figure out whether particular theories held by historical figures were true or false?

No, not really. Not any of those things. Scholarship in the history of philosophy is mainly like this: there are certain books that we have had for a long time, by a certain list of canonical major figures in philosophy. You read the books of a particular philosopher. Then you pick a particular passage in one of the books, and you argue with other people about what that passage means. In making your arguments, you cite other things the philosopher said. You also try to claim that your interpretation is “more charitable” than some rival interpretation, because it attributes fewer errors, or less egregious errors, to the great figure.

This pretends a breathtaking unfamiliarity with modern history of philosophy. The answers in fact are: (1) everything, (2) yes (example), (3) yes (example), and (4) yes (example).

Frankly, I don’t think there is much difference between the rhetorical-question activities and the ones that occur in Huemer’s actual answer. How does Huemer draw the line between “good” history of philosophy and “bad” history of philosophy? When a contemporary philosopher reads a dead one, and then summarizes what they say, at what point does this person start doing “bad” history of philosophy? Is it when they cite more than three books? Is it when they consult different translations? Is it when they visit an archive? When should the philosopher stop trying to figure out what they dead one meant and just report their impression of what was meant? Though there may be a difference of degree here, there is no real difference in kind between the activity being done in “good” history of philosophy, of which Huemer approves, and “bad” history of philosophy, of which Huemer disapproves.

In Section 2, Huemer suggests that the most we can achieve in history of philosophy is to understand what philosopher meant. But because this in itself gives us no evidence for the truth or falsity of what the philosopher claimed, Huemer says, “This is of no philosophical import.” But nobody would deny that we need to know what a claim means in order to determine whether our present evidence justifies a claim. The former cannot be done without the latter, particularly because most people read older works in translation. The evaluation of editing and translation is also part of history of philosophy. Is the alternative to just read Plato without critically considering the text itself? This cannot be done because what Plato said is not manifest.

This suggests that Huemer is mistaken in Section 3 in claiming that philosophers can just pick up a text and explain it well enough. The text is an object of scholarly scrutiny. The text is not given to us: it takes time and energy to understand. And here, Huemer’s argument cuts both ways: we could equally have just historians of philosophy because they could explain contemporary philosophers “well enough for undergraduates.” I could see a university provost making the same argument for replacing all philosophers with shared duties among faculty in other departments. Such a provost would be just as wrong as Huemer is here.

In Section 4, Huemer suggests that studying a dead philosopher too much can skew your modern perspective. Moreover, dead philosophers like Aristotle don’t have the benefits of “access to the accumulated human knowledge of the last 2,000 years.” But I don’t see that the modern perspective is not itself skewed in much the same way, as would probably be attested to by folks in future years if they were asked about our perspective. Appealing to what Martin Lenz has called “unquestioned teleological bullshit” about the march of progress is not particularly persuasive. And Huemer’s position that most philosophers are mostly wrong about most things makes it particularly difficult to defend the claim that living philosophers’ views are so superior to those of dead philosophers that we can or should discard history of philosophy.

A milestone in LibriVox recording!

With the new decade approaching, I am happy to brag about a milestone that I recently hit: as a reader for LibriVox, I have just broken 48 hours of recorded works! One could listen to philosophy works for another two full days, though this is not doctor-recommended (either by medical practitioners or by PhDs!). The recording that put me over this line was Russell’s 1920 The Practice and Theory of Bolshevism–which is just in time for its 2020 centenary!

While we are here: LibriVox is a non-profit organization that produces public domain audio books of works whose copyright has lapsed (generally, stuff published before 1923). You are strongly encouraged to pitch in by recording your favorite philosophical work yourself!

Indeed, much has been written about the urgent need for public philosophy (here, here, and here, for example). The need is sufficiently great that the American Philosophical Association even has a committee on public philosophy. I see volunteering for LibriVox as one very fun way of answering that need by making philosophy more accessible to members of the public. As the APA’s statement on public philosophy notes:

Public philosophy is done in a variety of traditional and non-traditional media. Public philosophy can be especially valuable when it reaches populations that tend not to have access to philosophy and philosophers.

Audio books certainly count as non-traditional media, and can reach populations that may not otherwise have easy access to these philosophical works. So if you don’t have an article handy to submit to the Public Philosophy Journal, give recording someone else’s words–aloud–a try! You might make a real difference in someone’s honest efforts to philosophize, and you may even get a heartwarming note like this one:

Thank you very much for undertaking this project. You’ve helped me enormously. I’m a graduate student in philosophy, a mother of the school-aged children and I have ADHD. Thanks to your efforts, I have been able to listen your various recordings of Russell’s works as I drive around or complete other tasks rather than to have to devote all my attention to reading. I cannot overstate the extent to which this has improved my lives and as a result, the lives of my children. Your enunciation is clear and your intonation in no way obfuscated Russell’s intended meaning. That is no small feat when it comes to any given piece of philosophy, let alone philosophy as prolix and technical as Russell’s. Thank you again, truly. —Mindscent

Dan Baras on the Absolute Authority view

Dan Baras (Hebrew University of Jerusalem) has recently published an excellent paper, “A Moral Argument Against Absolute Authority of the Torah” in Sophia. The reason I want to describe its contents and arguments here is because I think that it would be a useful essay in philosophy of religion courses, and possibly in introduction to philosophy and elementary ethics courses. The paper was recently made freely available for a week-long online symposium organized by the Association for the Philosophy of Judaism.

Although Baras takes Orthodox Jewish views on the authority of the Torah (here, Bible plus Talmud) as good examples of the Absolute Authority view, Baras argues against any view on which a collection of texts is taken to have absolute authority, so it would presumably cut against textual absolutism in any religious tradition (page 2, footnote 1).

Baras is also not arguing against religious practice and belief, nor even against following the prescriptions and rules codified in the Torah (page 3). Baras is not even arguing that the authors of the texts should be blamed for promoting the texts, nor that the norms are worse relative to prevailing norms in the area at the time (page 11). Baras argues specifically against Absolute Authority view (page 4):

Doctrine of Absolute Authority: Whenever there is a course of action φ such that the Torah prescribes that you φ, that is a conclusive reason to do φ. (And conversely, whenever there is a course of action φ such that the Torah prescribes that you do not φ, that is a conclusive reason not to φ.)

Baras argues against the Absolute Authority view as follows (page 5):

  1. The Torah includes norms that we strongly judge to be immoral.
  2. If the Torah includes norms that we strongly judge to be immoral, then it does not make sense to treat the Torah as an absolute authority.
  3. Therefore, it does not make sense to treat the Torah as an absolute authority. (From 1 and 2)

Premise 1 is supported with examples from the Torah (Bible plus Talmud). Premise 2 is defended by exhaustively considering four kinds of bases for accepting an authority, and then arguing that, given our knowledge of this Torah’s origins, none of these bases can support accepting the Absolute Authority view. Independent of the plausibility of these premises, in my estimation, this argument will definitely get students engaged. I am eager to see how it goes and report back!

One thing that struck me was that the motivation for arguing against this view. Baras argues that this doctrine leads people to a kind of refusal to admit the alleged ethical wrongs in the Torah:

What bothers me, and has motivated me to develop this argument, is the inability that I find among my religious peers…to state clearly that they reject the passages from the Bible and Talmud in the next section, as well as many others that are similarly morally appalling.

I really appreciated Baras’s sharing of autobiographical details that are relevant to, and motivate, the philosophical content. It is refreshingly honest to see this acknowledged explicitly.

This motivation is part of the reason why I think this piece would be useful in facilitating discussion. A lot of students in the States, at least in my experience, come from religious backgrounds where something in the neighborhood of an absolute authority view is accepted. This causes tension between our deeply felt ethical convictions and the norms with which many of us grew up.

This tension raises tons of interesting and engaging philosophical questions about the nature of texts, the conflict between ethical beliefs and obedience to longstanding rules, and active cognitive reflection on our own beliefs. At any rate, the article is careful and interesting, and I highly recommend to those interested in the topic that they give it a look!

What was Russell’s objection to the coherence theory of truth?

This post is inspired by a fun thread from Michael Bench-Capon:

This is a nice question. In Problems (pages 191-192 in this edition from Russell gives two objections—in typical fashion, he calls them “great difficulties”—against the coherence theory of truth:

The first [objection] is that there is no reason to suppose that only one coherent body of beliefs is possible. […] The other objection to this definition of truth is that it assumes the meaning of “coherence” known, whereas, in fact, “coherence” presupposes the truth of the laws of logic.

I ignore the first argument here because Bench-Capon’s thread does not concern the first argument. Russell next argues for his second claim about coherence theories:

Two propositions are coherent when both may be true, and are incoherent when one at least may be false. Now in order to know whether two propositions can both be true, we must know such truths as the law of contradiction. For example, the two propositions “this tree is a beech” and “this tree is not a beech” are not coherent, because of the law of contradiction. But if the law of contradiction were itself subjected to the test of coherence, we should find that, if we choose to suppose it false, nothing will any longer be incoherent with anything else. Thus the laws of logic supply the skeleton or framework within which the test of coherence applies, and they themselves cannot be established by this test.

The idea here is that one cannot specify what coherence means without invoking the notion of truth. That is, in order to explain what it means for a collection of beliefs to be coherent, we will need to say that they can all be true. But this is just to invoke the notion of truth, or at least the possibility of their all being true, to explain their coherence. And because the coherence theory was supposed to explain what truth is, this is just to explain what truth is by appealing to what truth is.

Russell points out that one will need the logical laws to be true independently of their coherence with any given body of beliefs in order to give any belief-system independent criterion of coherent bodies of beliefs. How does that go? The example of the beech tree indicates what Russell has in mind. Suppose I accept the coherence theory of truth, and that I further think that a collection of beliefs is coherent when all the beliefs in question could be true. But now I say that the collection of beliefs B containing p and not-p is incoherent. And somebody asks, “Why is B incoherent?” Presumably, I will need to explain this by appealing to the impossibility of both p and not-p being true. But now we have completed the circle and arrived back at truth, which was our starting point.

Russell puts the same point in a slightly different way in a 1907 essay, “The Nature of Truth” (pages 156-157 of this edition from He in effect argues that the coherence theorist cannot explain why some collections of beliefs are coherent (somehow correct) and others incoherent (somehow in error) without appealing to the notion of truth:

…we are concerned with the question, not how far a belief in the coherence-theory is the cause of avoidance of error, but how far this theory is able to explain what we mean by error. And the objection to the coherence-theory lies in this, that it presupposes a more usual meaning of truth and falsehood in constructing its coherent whole, and that this more usual meaning, though indispensable to the theory, cannot be explained by means of the theory. The proposition “Bishop Stubbs was hanged for murder” is, we are told, not coherent with the whole of truth, or with experience. But that means, when we examine it, that something is known which is inconsistent with this proposition. Thus what is inconsistent with the proposition must be something true; it may be perfectly possible to construct a coherent whole of false propositions in which “Bishop Stubbs was hanged for murder” would find a place. In a word, the partial truths of which the whole of truth is composed must be such propositions as would commonly be called true, not such as would be commonly called false; there is no explanation, on the coherence-theory, of the distinction commonly expressed by the words true and false, and no evidence that a system of false propositions might not, as in a good novel, be just as coherent as the system which is the whole of truth.

I like this passage because it shows that Russell is concerned with the ability of the coherence theorist to explain truth using coherence. Russell’s challenge is to specify what coherence means independently of the notion of truth. Russell’s view is that this cannot be done.

It might be useful to put it a little differently. Suppose I am a coherence theorist. Let B be a collection of beliefs that is incoherent because, say, it contains p and not-p. In explaining what coherence is, I have two choices: (a) I can say that B is incoherent because p and not-p violate the logical principles included in B, or (b) I can say that B is incoherent because p and not-p violate logical principles not included in B.

Strategy (b) gives up the coherence theorist’s game. Appealing to logical laws that are true independently of their coherence with the body of beliefs B is just to give a test of truth of beliefs contained in B using the impossibility of their both being true. But truth was the very thing that coherence was supposed to explain.

On the other hand, strategy (a) does not explain why some collections of belief are true and others are not. If the only test of coherence is through internally accepted logical principles, then there is no way to say, of a given body of beliefs, that it is coherent or incoherent. One cannot give a belief-independent explanation of coherence at all. There is nothing to which you can appeal in making this judgment besides the internal logical principles of a given collection of beliefs.

Well, why should that be so bad? Assume that all judgments of coherence are, to borrow a Carnapian phrase, internal questions. Russell’s objection still stands: it is just that the coherence theorist is not able to offer an account of what makes a given body of beliefs coherent. Even on strategy (a), to say what coherence is, one would first have to pick a coherent belief system, then explain what coherence means in general. But if all questions about coherence are internal, then this is precisely what we cannot do.

As a side note, the Stanford Encyclopedia of Philosophy article on the Coherence Theory of Truth calls Russell’s objection the specification objection. I do feel that the summary there overlooks that strategy (a) does not answer Russell’s objection of stating what it means in general for a given collection to be false and for another to be true, but the clear distinction of internal and external questions may be, in Russell’s development, a post-Carnap conceptual development that should not be held against the 1907-1912 fellow.