As the aim of this chapter is to suggest a framework whereby philosophical approaches can find their way back into mainstream biological research, a brief survey of the apposite history of philosophy and rational inquiry is presented in this section. Each subsection here, particularly Aristotle’s biology, can be a vast and separate strand of investigation. Nonetheless, the purpose here is to look at snippets of inspiration for a philosophical biology framework. Before proceeding, however, it is important to point out why looking for lessons in philosophy applicable to current problems in biomedicine could be a fruitful strategy: first, philosophy does not have a “state-of-the-art.” This is fortunate, I think, because philosophy is simply a mode of thought and inquiry that once arrived at, can stand the test of time and be applicable to different situations and scenarios. This is not surprising, because modern humans’ cognitive capacities have not changed much since the emergence of our language faculty (Berwick and Chomsky
2015,
2017), and as such the philosophical achievements of Plato (ca. 428–348 BC) or Aristotle (384–322 BC) more than 2400 years ago may represent some of the limits of what could be achieved theoretically in certain domains of thought. Second, true philosophy is not based on mere debates,
5 where there is no room for the interlocutors to change their minds and learn from the other, but rather, philosophy is based on arguments that could build on each other and that allow for thought experiments to advance one’s knowledge.
3.1 Ancient Philosophy
Plato’s dialogues offer a wealth of concepts relevant to the discussion here. The rational question-and-answer-based method Plato uses in the dialogues is usually called the Socratic (or “elenctic”)
6 method, which is of a “maieutic”
7 nature (Leigh
2007). In other words, a sequential and adaptive question-based style of reasoning can lead one (or a group of individuals) to introspect toward new and improved reasoning. This can be said to parallel the process of hypothesis generation in a scientific inquiry. Each dialogue, such as the
Theaetetus, provides specific instances of the usages of this methodology. Clark Glymour and colleagues point out that the dialogue
Meno is “the source of a [philosophical] method: conjecture an analysis, seek intuitive counterexamples, reformulate the conjecture to cover the intuitive examples of the concept and to exclude the intuitive non-examples; repeat if necessary” (Glymour et al.
2010). This seems to be the perfect recipe for thought experiments.
One can also find hints of the use of simple models for testing or observation before moving on to the actual phenomenon in question. This can be read in the
Sophist, when the Eleatic Stranger/Visitor says to Theaetetus, a mathematics pupil (and later of great fame as a geometer): “when it comes to grappling effectively with any of the big subjects, everyone has long thought it best to practise on small and easier things before moving on to the big ones themselves”
8 (218c5/d1) and also that “we should pursue something of no consequence and try to establish it as a model for the more important subject” (218d5). There is an analogous message in Aristotle’s
Parts of Animals (
PA): “If any person thinks the examination of the rest of the animal kingdom an unworthy task, he must hold in like disesteem the study of man. For no one can look at the primordia of the human frame—blood, flesh, bones, vessels, and the like—without much repugnance” (
PA I.5).
9
In addition to philosophy and logic, Aristotle’s perceptive and meticulous observations of nature make him a foremost naturalist (Romanes
1891). His writings on biology have received varying levels of attention from scholars in different periods. Sophia Connell notes that “because Aristotle himself does not attempt to distinguish the biological from the philosophical, it makes sense to read all Aristotelian texts as potentially representative of the same philosophical outlook” (Connell
2001). A great portion of Aristotle’s observations are detailed descriptively which may be followed by inferred conclusions. The observations themselves may be firsthand or referenced from others. Commenting on Aristotle’s
History of Animals (
HA), for example, I. M. Lonie notes: “In a celebrated passage [
HA III.2 and III.3] [Aristotle] describes the theories of Syennesis, Diogenes of Apollonia, and Polybus, on the blood vessels, in all of which the heart is subordinate to the brain. After recording their views, Aristotle remarks [
HA III.3] that these men and other natural philosophers were mistaken: the blood vessels begin from the heart, not from the brain” (Lonie
1964).
But there are also general accounts to be found in Aristotle’s biology. A case in point is his four categories of traits which could frame one’s investigation of life in nature: ways of life (
bioi), actions and activities (
praxeis), dispositions and character (
ethê), and parts (
moria) (Depew
1995). Of these general accounts, I would like to point to a few methodological proposals. First, in
PA I.4, Aristotle indicates
analogy and
difference measurements as two modes of comparison: “Groups that only differ in degree, and in the more or less of an identical element that they possess, are aggregated under a single class; groups whose attributes are not identical but analogous are separated.” The method of “the more and the less” is quite reminiscent of the earlier discussion on
P-values and effect size.
10
In the
Generation of Animals (
GA), Aristotle makes an important distinction between the
potential and the
actual, stating that “all three kinds of soul [nutritive, sensitive and rational] … must be possessed potentially before they are possessed in actuality” (
GA II.3).
11 In
De Anima (
On the Soul) III.5, he explains this notion to a greater extent, writing that “in a sense light makes potential colours into actual colours.”
12 Connell provides a further helpful example from
Metaphysics IX.7: “is earth potentially a human being? No […] just as earth is not yet potentially a statue, because it must undergo a change before it becomes bronze” (Connell
2001). The potential/actual dichotomy may first and foremost bring to mind today’s fields of developmental biology and genetics/inheritance. But it also brings into discussion the potential role of a living being’s environment, and epigenetics. Although beyond the purview of our present discussion, I think it is important to mention that reading the
GA with an eye on epigenetic development (Henry
2018) should always be accompanied by the determinants of “scope and limit”: A fish embryo, although susceptible to certain variations, cannot naturally develop into a bird, or another species: a scope comes hand-in-hand with limits, and therefore epigenetic variation in development is considerably constrained.
13
A third, and perhaps the most famous of Aristotle’s methodological proposals, is the categorization of causes. In
Physics II.3, he introduces the four as follows
14:
Material cause is “that out of which a thing comes to be and which persists,” e.g., “the bronze of the statue.”
Formal cause is “the form or the archetype.”
Efficient or moving cause is “the primary source of the change or coming to rest” or “what makes of what is made and what causes change of what is changed.”
Final cause is “in the sense of end or ‘that for the sake of which’ a thing is done, e.g. health is the cause of walking about.” In giving illustrations of each of the causes, one could rely on examples from the crafts, but as Connell points out, “the natural world is not constructed and does not work just like the crafts; indeed, the reverse seems to be the case—crafts copy nature. Natural objects take priority in Aristotle’s ontology, possessing properties that crafts will never be able to exemplify” (Connell
2001). Can one or more types of causes be reduced to each other under some circumstances? This appears plausible, particularly for biological applications. John Cardwell relayed a similar message more than a century ago: “as ‘form’ includes, by definition,
all the properties of a material thing, the ‘formal cause’ may, in some instances, include both the ‘efficient’ and ‘final’ causes, thus reducing the four to two, and bringing one back to the primal dual postulate, i.e., matter with ‘form’” (Cardwell
1905).
This dual theme of matter and form is quite important and pertinent to some of the current impediments in biomedical research, for the focus in the discipline—for practical or other reasons—has usually solely been on material causation. Here in particular I have in mind the mechanistic framework of investigation in contemporary cellular and molecular biology. Might it be possible to augment mechanisms with biological “binding principles,” with the former acting as the material and the latter as the formal causes in an intelligible account of a biological phenomenon (Ehsani
2019)? Moreover, a research area today where ascriptions of causality are in need of significant attention and work might be the field of randomized controlled trials, which “seem poorly suited for answering questions related to why therapies work in some situations and not in others and how therapies work in general” (Carey and Stiles
2016). In these trials, it is not uncommon to have a classification called “all-cause mortality.” In a trial published in 2018 (McNeil et al.
2018), for example, the list of all-cause mortality included: cancer, cardiovascular disease, major hemorrhage, “other,” and “insufficient information” (12 out of 1052 patients). For concepts such as “all-cause mortality” and related (and derived) theoretical notions, much can be done along the theme of this section.
Aristotle’s methodology may often be thought to revolve around
aporíā (i.e., difficulties, impossibilities or puzzles). Michael Frede makes a connection between Aristotle’s approach to such puzzles and that of Plato in the
Sophist: “[The
Sophist] sets out carefully constructing a series of puzzles,
aporiai [… and] then it turns toward a resolution of these
aporiai. In this regard the procedure of the dialogue reminds one of the methodological principle Aristotle sometimes refers to and follows, the principle that on a given subject matter we first of all have to see clearly the
aporiai involved before we can proceed to an adequate account of the matter, which proves its adequacy in part by its ability both to account for and to resolve the
aporiai” (Frede
1992, p. 423).
A few centuries after Aristotle, Galen (of Pergamon, (ca. 129–210 AD)) also made his own lasting impressions on the philosophical pursuit of human biology.
15 Ronald Christie reminds us that “what Galen taught is of great importance since his writings dominated medical education for the next 1500 years” (Christie
1987). Eva Del Soldato, writing on the “Renaissance debate over the superiority of Aristotle or Galen,” observes that “Aristotle was regarded by physicians as an important authority because of his philosophical system, but Galen had offered in his works more precise observations of the human body. Nonetheless, since many points of their disagreement (e.g., the localization of the brain functions) were merely founded on speculation, some doctors preferred to demonstrate the harmony between Aristotle and Galen in order to overcome this impasse” (Del Soldato
2019). Galen himself thought highly of Aristotle and Hippocrates
16: “All these and many other points besides in regard to the aforesaid faculties, the origin of diseases, and the discovery of remedies, were correctly stated first by Hippocrates of all writers whom we know, and were in the second place correctly expounded by Aristotle” (
On the Natural Faculties II.4).
17 It is in this context that I would like to briefly move back a few centuries before Galen and mention Erasistratus (ca. 304–250 BC), who “was regarded by his followers as a successor to Aristotle and Theophrastus” (Lonie
1964). Christie, writing on Galen’s critical reception of the teachings of Erasistratus, remarked that “the school of the Erasistrians survived until after the time of Galen, who did a great disservice to medical progress by destroying its credibility with rhetoric based on sarcasm and ridicule” (Christie
1987). This is due to the fact that “Erasistratus discarded most of the humoural theory of disease in favor of one based on changes in individual organs,” which is closer to modern medical approaches. But in certain other areas, Erasistratus did not make progress
from today’s point of view: Lonie, for example, points out that “what prevented Erasistratus, and any other ancient physiologist, from advancing a systematic hypothesis on the circulation of the blood was not so much the failure to realize how it might be possible mechanically. The obstacle was more deep-seated than that: it was a failure to see beyond the analogies which they employed in their physiological systems [e.g., the blood supply vs. an irrigation system]” (Lonie
1964). Here one is again reminded of the machine analogy that is inherently tied to mechanistic accounts in modern biology. Other commonly-used analogies such as protein “folding,” “intrinsic disorder,” and “interaction” are further instances of this phenomenon. Overall, being cognizant of the limitations of analogies borrowed from their ordinary language usage may limit their potential pitfalls.
3.2 After the Galilean Revolution in Science
If openness toward natural puzzles, paradoxes, and thought experiments is one message from the preceding section, then perhaps Galileo Galilei (1564–1642) is a quintessential figure in the history of rational thought adhering to this method. Galileo allowed himself to be puzzled by seemingly mundane phenomena, leading him to perform “scientific” (i.e., rational) thought experiments where few others—as far as can be ascertained—had made any significant advances. Nowhere is this more pronounced than his thought experiment about a moving ship (1632), which convincingly demonstrated that to a person present on a stationary ship versus one on a moving ship with constant velocity, all types of motion would appear the same in both scenarios. The result of Galileo’s work, along with those of René Descartes (1596–1650) and Cartesian philosophers following him was the establishment of the mechanical philosophy as an intelligible overarching account of natural phenomena and the appreciation that the world was
directly understandable (Chomsky
2009). The new science of mechanics of Isaac Newton (1643–1727) changed all of this, whereby
action at a distance could no longer allow for a cogent account of “matter” and “physical” to be given. Thus, the effect of the new Newtonian mechanics was to revive some of the Aristotelian (and Scholastic) notion of “mysteriousness” in the science of the day. Indeed, this mysteriousness about the nature of matter remains to this day.
What Newton tried to avoid was “explaining what is ‘unknown’ by what is ‘more unknown’” (Cohen and Smith
2004, p. 25). This mantra, along with Christie’s caution against “dogmatism [which] can be a dishonest or insincere substitute for ignorance” (Christie
1987), become especially apropos if the implications of Newton’s undermining of the mechanical philosophy are to be implemented. Namely, post-Newton, it became clear that the world cannot be directly intelligible and hence only the intelligibility of
theories about the world could be contemplated (Chomsky
2014b). When one attempts to—in the words of the physician Paracelsus (1493–1541)—“inquire of the world” (Lister
1957), rather than merely recording and measuring it, the end result of the process would be to attain simpler, more intelligible and better explanatory theories. Therefore, theory is not
removed from the reality of nature; rather, as far as we as human beings can tell, theory
is our reality of nature.
Let us now pick one important theory of nature, i.e., that of causality, and briefly investigate how it changed post-Galileo compared to Aristotle’s account of the four causes. John Locke (1632–1704), in the first volume of his 1689
An Essay Concerning Human Understanding, offered an account of causality that may still inform today’s use of mechanistic explanations in biology: “for to have the idea of cause and effect, it suffices to consider any simple idea or substance, as beginning to exist, by the operation of some other, without knowing the manner of that operation” (Locke
1894).
18 A few decades later (in 1748), David Hume (1711–1776) offered an account of causality, and a commentary on its “ultimate springs and principles,” that rings true with an enduring tone:
Hence we may discover the reason why no philosopher, who is rational and modest, has ever pretended to assign the ultimate cause of any natural operation, or to show distinctly the action of that power, which produces any single effect in the universe. It is confessed, that the utmost effort of human reason is to reduce the principles, productive of natural phenomena, to a greater simplicity, and to resolve the many particular effects into a few general causes, by means of reasonings from analogy, experience, and observation. But as to the causes of these general causes, we should in vain attempt their discovery; nor shall we ever be able to satisfy ourselves, by any particular explication of them. These ultimate springs and principles are totally shut up from human curiosity and enquiry. Elasticity, gravity, cohesion of parts, communication of motion by impulse; these are probably the ultimate causes and principles which we shall ever discover in nature; and we may esteem ourselves sufficiently happy, if, by accurate enquiry and reasoning, we can trace up the particular phenomena to, or near to, these general principles. The most perfect philosophy of the natural kind only staves off our ignorance a little longer: as perhaps the most perfect philosophy of the moral or metaphysical kind serves only to discover larger portions of it. Thus the observation of human blindness and weakness is the result of all philosophy, and meets us at every turn, in spite of our endeavours to elude or avoid it. (Hume
1902)
19