What is Life?:How chemistry becomes biology (7 page)

So how to proceed? In an insightful article published a decade ago, Carol Cleland, who teaches philosophy at the University of Colorado, and Christopher Chyba, a Princeton University astronomer, changed the very nature of the debate.
¹⁹
They pointed out that attempting to define life before we understand what life is, is to put the cart before the horse. Seeking the definition of an entity that we
do
understand is problematic enough. Attempting to define an entity that we are still struggling to understand is futile. Based on the Cleland and Chyba argument, we can now identify the fundamental problem with the NASA definition. The NASA definition
does not attempt to tell us what life
is,
but rather how we might recognize it. Just as water’s physical characteristics might help us determine if some liquid is water or not, the NASA definition may be able to inform us if something is alive by seeing whether it does something that living things typically do (undergo Darwinian evolution). Cleland and Chyba claim that what is needed is not a definition of life, but a comprehensive
theory of life.
We will describe our attempts in that direction in the final two chapters.

To sum up, this brief historical survey has illustrated the confusion that the life issue has generated over the centuries right through to the present day, as well as some of the reasons that the long-standing ‘what is life’ riddle has remained unresolved. Until the deep conceptual chasm that continues to separate living and non-living is bridged, until the two sciences—physics and biology—can merge naturally, the nature of life, and hence man’s place in the universe, will continue to remain gnawingly uncertain.

The previous chapter indicated that we are still lacking a theory of life, a theory that will enable us to understand what life is and how it emerged, that despite the recent detailed insights into life’s mechanism, something central is missing in our understanding of the life phenomenon. But what exactly do we mean by the term ‘understand’? When addressing most day-to-day questions, there seems to be no need to explain the term—it is self-evident. But when addressing the life question, the issue turns out to be more complex. What we mean by ‘understanding’ goes to the very heart of the scientific method and beyond, forcing us to at least briefly address basic philosophical questions that have weighed on mankind for over 2,000 years.

In the scientific world we strive to achieve understanding of phenomena in the world around us through application of the
scientific method.
The method is well known so we will just address those aspects that will be relevant to our analysis. At the very heart of the scientific method is the
process of induction,
a way of reasoning
whose roots can be traced back to ancient Greek philosophy, but was raised to scientific prominence with its formal description by Francis Bacon, one of the fathers of the modern scientific revolution. This may all sound quite formal, even esoteric. But the essence of the methodology is actually very simple. So simple in fact that even young children intuitively understand it and (unconsciously) apply it quite routinely. Indeed, I would argue that the essence of all scientific endeavour, stripped of its many elaborations, trimmings, and jargon, is nothing more than the successful application of the inductive method. It is the successful application of the inductive method that forms the basis for what we term ‘understanding’.

Inductive reasoning involves the reaching of general conclusions from a set of empirically obtained facts—what one might simplistically term
pattern recognition.
Consider a very simple example: the falling of apples. Indeed without exception, all apples do fall, so one can reasonably formulate a general rule of nature: ‘apples fall’. However, even the less observant amongst us will have noticed that it is not just apples that fall, but that all material objects display that same falling characteristic. Accordingly, the limited ‘apples fall’ rule can be further extended to an ‘all objects fall’ rule, though the behaviour of certain objects, such as hot-air balloons, requires the pattern to be elaborated further to account for these apparent exceptions.

Needless to say the phenomenon of falling objects is so obvious that even a small child grasps its essence very quickly and in doing so has applied the inductive method at a fundamental level. When a child drops some object and it falls to the ground, it doesn’t take too long before the child ‘understands’ that the singular event of the falling object manifests the general ‘objects fall’ rule. So even young children,
with no knowledge of induction or the scientific method, intuitively apply the principles of induction to better understand and adapt to the world around them. Thomas Macaulay, a British poet and historian, pointed this out already over 150 years ago with hiscomment:

The inductive method has been practised ever since the beginning of the world by every human being. It is constantly practised by the most ignorant clown, by the most thoughtless schoolboy, by the very child at the breast. That method leads the clown to the conclusion that if he sows barley he shall not reap wheat. By that method the schoolboy learns that a cloudy day is the best for catching trout. The very infant, we imagine, is led by induction to expect milk from his mother or nurse, and none from his father.
²⁰

In fact
all
cognitive beings, human and non-humans alike, apply the method routinely, whether consciously or subconsciously, in a process that has been deeply engrained in us all by evolution. Yes, your pet dog, despite his lack of familiarity with Bacon’s treatise, or epistemology in general, also routinely applies the inductive method. Just watch his reaction when you begin to open a can of his favourite dog food. Based on the pattern he has learnt to recognize over time, he fully understands that he is about to get fed. It is that evolutionarily acquired ability to gather empirical information and to recognize patterns within that gathered information which provides cognitive beings with the ability to respond to the external world in a beneficial manner (from the point of view of the cognitive being). Both your dog, a 2-year-old child, and the scientist in the lab are applying the same inductive methodology, the difference only being in the level of sophistication of the patterns that are recognized.

As mentioned above, small children recognize the ‘objects fall’ rule. But it took the genius of an Isaac Newton to recognize a much
broader pattern, one which links the behaviour of falling apples to the orbits of celestial bodies, such as the moon and the earth—a law of gravity that describes the interaction of physical bodies in precise mathematical terms. So when we say we understand
why
apples fall and
why
the moon rotates around the earth, it is because both these specific events exemplify a more general pattern, one that governs the behaviour of all physical bodies. But what that means, however, is that there is no
absolute and deep
understanding as to
why
apples fall. Gravity is just the name of the general pattern to which the falling apple event belongs.

Ultimately
all
scientific explanations are inductive—they involve no more than the recognition of patterns and the association of the specific within the general. Broadly speaking the wider the generalization, i.e., the greater the number of empirical observations that are embraced by the generalization, the greater its predictive power and the more significant the generalization. Simplistically, that’s what modern physics is all about—seeking ever-general laws that underlie the workings of the universe, extending the pattern. So that is what Einstein’s special and general theories of relativity do—they extend and generalize the more limited Newtonian pattern. With his theory of relativity Einstein was able to place Newton’s gravitational force in a more general context, and in that sense it constituted an advance on the Newtonian description.

According to Einstein, gravity is just the natural movement of objects through curved four-dimensional spacetime, thereby providing a more general basis for understanding a wide range of physical phenomena, including the behaviour of falling apples. And, of course, physicists are still at it, attempting to further generalize, with sophisticated formulations such as string theory and M-theory, constantly
working toward the so-called final theory—the theory of everything, the ultimate pattern. Of course whether an ultimate pattern is achievable is another question, one that belongs within the realms of philosophy, not just science—a wonderful question in its own right, but one that goes well beyond the scope of this discussion.

The role of mathematics in generating patterns is crucially important. The ability to express the pattern quantitatively through the language of mathematics greatly enhances the predictive power of the generalization and therefore its utility. Richard Feynman, the Nobel physicist, once compared the accuracy of quantum theories to the ability to measure the width of North America to an accuracy of one hair’s breadth. Now that’s a pattern we should take note of! Such predictive capabilities ensure that mathematics plays a central role in pattern formulation, though this is not to dismiss the value and utility of qualitative patterns. Let us not forget the revolutionary impact of Darwin’s ideas of natural selection and common descent, ideas that were entirely qualitative in their formulation yet continue to profoundly impact on man’s view of himself to this very day. To quote the aphorism attributed to Albert Einstein:
Not everything that counts can be counted, and not everything that can be counted, counts.

We have used the term ‘patterns’ to describe what it is that the inductive method seeks, though scientists typically use other terms, such as hypotheses, theories, laws, to mention the main ones, the difference being primarily in the degree to which the pattern has been confirmed. Thus Newton’s Law of Gravity is uncontroversially considered to be a law due to the innumerable times apples and other objects have fallen, and the regularity with which the sun rises every day. However, the term ‘pattern’ with its inherent fuzziness, does have its advantages. In contrast to terms such as ‘theories’ and
‘laws’ which radiate some sense of absolute truth, the term ‘pattern’ is more subtle, less committed, less definitive, more open to modification. Even Newton’s laws, those pertaining to gravity and motion, have had to undergo revision following Einstein’s revolutionary insights. If we keep in mind that every hypothesis, theory, or law is ultimately just a pattern, the day that theory or law is modified or revoked will be less surprising, less disconcerting.

As to the underlying reason for the existence of those patterns, rules, laws, generalizations, or whatever we wish to call them, science is unable and does not pretend to address such questions. Despite the widespread view that the laws of nature are the explanation of natural phenomena, Ludwig Wittgenstein, the great twentieth-century philosopher, pointed out almost a century ago in his famous
Tractatus
(Latin for
treatise
) that ‘the whole modern conception of the world is founded on the illusion that the so-called laws of nature are the explanations of natural phenomena.’ There is no fundamental explanation for
any
phenomenon and the best we can do is to say that the pattern is the explanation. Patterns are the link between the underlying reality and our understanding of that reality. The basis for the patterns, those underlying laws of nature, are fascinating questions in their own right, but these are philosophical questions, beyond the strict scientific domain, and therefore outside the scope of this discussion. To quote Wittgenstein yet again: ‘whereof one cannot speak, thereof one must be silent’.

Given the above statements it can be appreciated that there are degrees to understanding, that understanding is to a significant extent
subjective,
because the process of pattern recognition is not always definitive. Pattern recognition is, to some extent, in the eye of the beholder. As the Nobel physicist Steven Weinberg lucidly
pointed out, as good a way as any to establish whether a pattern is insightful is to see whether it induces an ‘Aha!’ from colleagues. Having said that, however, it is clear that the nature of understanding within physics, a more fundamental science, is quite different from its operation within biology, whose domain is the study of inherently highly complex systems. Within physics generalizations are invariably rigorously quantified, articulated in the language of mathematics so that exceptions to the rule are not tolerated and require a reformulation of that rule. Within biology generalizations are frequently qualitative and exceptions to the rule are not just tolerated, but accepted as normal. In any case, regardless of the field of endeavour, it should be emphasized that the same set of observations may on occasion be interpreted in different ways and so may lead to the recognition of different patterns.

This is particularly true when the observed patterns are statistical rather than absolute, as is common in the social sciences, or when the patterns are qualitative rather than quantitative in nature. It is for this very reason that historians frequently come up with quite different models for understanding a set of historic events, since those events may be successfully organized in more than one pattern. The extensive literature on the causes of the First World War exemplifies the way an unambiguous set of historical events can be understood and interpreted in different ways. Nor do patterns have to be mutually exclusive. Both a 2-year-old child and a theoretical physicist have some understanding of why apples fall, though their explanations differ markedly. Both see in the falling apple the manifestation of a more general pattern, though the physicist recognizes a pattern that is both broader and quantifiable. Significantly however, the child’s simple ‘falling object’ rule is sufficient to serve him extremely well on
a day-to-day basis. So provided that the child has no immediate plans to launch a satellite into space or undertake space travel, then for all practical purposes the extra insight that Newton’s law of gravity and Einstein’s theories of relativity offer into the behaviour of matter, beyond that offered by the ‘objects fall’ rule, will be of little consequence. In fact, if one thinks about it, the physicist about to undertake some mountain climbing is most likely to be applying the ‘objects fall’ rule to guide him in his adventure, rather than string theory or special and general theories of relativity.