Explanations of Life

Suppose we encounter life forms on another planet unrelated to ours and possibly quite unlike ours. Still, there is evident adaptive complexity, so that the laws of physics and chance cannot explain what we observe. What possible explanation might be given for this complexity? How might it have come to be?

            One possibility is intelligent design—not by God, to be sure, but by scientifically advanced aliens. These organisms might have been synthesized on a Life Production Machine. They are in effect artifacts of another civilization, so the explanation of their existence matches the explanation for the existence of artifacts in our civilization: intentional intelligent design. We can’t rule this explanation out; it is a matter of empirical fact whether it is true (just as it is for life on earth). We might well gather further information that rules out the hypothesis (there is no such advanced civilization in the vicinity), but as a matter of principle the hypothesis is a theoretical possibility—it cannot be excluded a priori. Alternatively, the life forms might have arisen by ordinary natural selection with no intelligent intervention. But there are also mixed cases: the organisms might have been subjected to guided breeding after a period of natural evolution, or they might be genetically engineered and then left to natural selection. Conceivably they might be selectively bred from an initial batch of bacteria, so partly the result of natural design and partly of intelligent design. There is an indefinite range of possible combinations of natural evolution and guided evolution, varying between species and planetary fauna—for instance, the mammals have been left to natural selection while the reptiles have been intensively bred for intelligence or strength. Maybe elsewhere in the universe all the possibilities have been tried—as is partially the case on earth where humans have artificially bred certain species but not others.

The traditional theoretical dichotomy between intelligent design and natural selection may be quite parochial where advanced civilizations have developed, because there is ample scope for partial intervention into the process of generating life. Selective breeding and genetic engineering can certainly speed up the evolutionary process considerably, taking decades to achieve what natural selection would take millions of years to achieve. When intelligent life forms take evolution into their own hands the sky is the limit. Naturally evolved life might be the most primitive form of life, vastly outclassed by the kind of life created by life itself, i.e. designed by life forms with the intelligence to change the course of evolution. No need to wait for that lucky chance mutation; just create whatever mutation looks promising and then subject the result to rigorous test. Just as bacteria look very primitive in the light of later evolutionary developments, so naturally evolved life might look very primitive compared to the kind of life that intelligent designers can contrive. If the secret to the origin of life is ever discovered, it could be used to re-start the entire process, producing untold wonders by creative intervention. All of life could come to be intelligently designed.

            Interestingly, the possibility of intelligent design depends upon antecedent natural design: not every life form in history could be the result of intelligent design, since an intelligent life form has to come from somewhere. No universe could create intelligent life ab initio: the long and painful process of natural selection has to create the first form of intelligence, since intelligence cannot depend upon other intelligence all the way down. But once a form of intelligence has evolved that is capable of selective breeding and guided evolution, it can produce new life forms without reliance on the old machinery of blind random mutation and natural selection. Then the explanation for the design of organisms will involve intelligent design not natural design. Most of the life in the universe might be of this kind: whole galaxies could be inhabited by intelligently designed organisms. Geological time is vast but cosmological time is much vaster, so the possibility of intelligently designed life coming to dominate the universe can’t be ruled out. We might be just at the beginning of the history of life—the short initial period in which life evolved naturally. Already we are beginning to change the course of evolution; genetic engineering could accelerate this process enormously. Other intelligent species elsewhere might be much further along in imposing their will on nature.

If a Charles Darwin is born on a planet that has been subject to intelligent design, he will hit upon the correct theory of evolution for that planet, namely evolution by intelligent design.  [1] Maybe life was seeded naturally by the accidental arrival of bacteria, but then intelligent creatures stepped in to guide the course of evolution, creating whatever organisms took their fancy. A rival theorist who hypothesized natural selection as the explanation would be mistaken; there was, on this planet, an intelligent designer responsible for the adaptive complexity on display. Natural evolution could have ended millions of years ago, with all life now the result of intentional intervention. The traditional Darwinian theory used to be true, but it is no more: everything is now carefully monitored and cultivated. This is what is taught in biology classes these days, and it is entirely correct. All genetic alteration is brought about by scientific intervention, so that nothing is left to chance; then certain strains are chosen for reproduction and others rejected. It is as if the old religious creationist story were true, only it is not a divine being calling the shots but a super-alien. On our planet now Darwin’s theory is the true theory, but on other planets the theory of intelligent design may be the true theory (and may come to be the true theory on our planet). There might come a time when none of the species inhabiting the galaxies evolved by natural selection. That was just the early phase in the history of life, and destined to be superseded by intelligent design. Evolution will cease to be blind.  [2]                                                                                         

  [1] His book On the Origin of Species defends the view that all life results from the intentional actions of a mighty intelligent designer. This Darwin might not know the identity of the designer—that was not discovered until space travel became a possibility centuries later—but he was brilliant enough to see that no other explanation could be true given the facts. Organisms were just too well designed for this to be a matter of blind variation and mindless selection! He considered the alternative theory but found it wanting—and he was entirely right in his conclusions and reasoning.

  [2] Just to be scrupulously clear, this essay is not intended to provide succor for creationists about life as it evolved on planet Earth; I am speaking of imaginary plants and imaginary ways of shaping life.

                                                Epistemology Personalized

What is it that is justified? Not propositions: they are true or false, but it would be strange to say that a proposition is justified independently of anyone believing it to be true (or probable). Was the heliocentric theory justified before anyone had any beliefs about it? It was true, but it wasn’t justified. So is it beliefs that are justified—or claims or statements? This is the way people usually talk in epistemology (“knowledge is true justified belief”, “the belief that ghosts exist has no justification”), but it is subtly wrong. This kind of talk makes it sound as if the relation of justification holds between evidence and beliefs without any mediation by a rational subject—as if the subject plays no essential role in the epistemic set-up. Evidence justifies belief and that is all. The belief can be justified or not, rational or not, independently of the epistemic subject. Evidence transmits justification to belief directly. The justification relation holds between evidence and belief.

            But that is not how we normally talk about justification. The canonical form of an ascription of justification is, “S is justified in believing that p”. It is the subject that is justified not the belief he or she forms. At any rate, the primary bearer of justification is the rational subject, with the belief’s justification following as a secondary and derivative matter. Just as it is the agent that is justified in acting in certain ways, so it is the agent that is justified in holding certain beliefs. You can see this from the fact that if you say of someone, “Her belief that p is justified” this could be true even though she is not justified in believing that p. The belief that p might be justified in virtue of evidence possessed by other subjects, while this subject has formed the belief irrationally. In order to determine if her belief is justified, in the intended sense, we need to ask whether she is justified in holding that belief. Generally, to say that the belief that p is justified is shorthand for saying that there are people who are justified in believing that p. When people are justified in holding certain beliefs we can say that those beliefs are justified, but not otherwise. It is not the belief state itself that is justified; it is a subject’s holding that belief. Similarly, it is not the assertion itself that is justified when someone makes an assertion; it is the speaker’s making that assertion. We cannot abstract the subject away from the relation of justification, as if justification merely involves relations between evidence and mental states or acts of speech. Justification is a triadic relation between evidence, belief, and person, not a dyadic relation between evidence and belief.

            Thus the person enters epistemology essentially. The basic thing that is justified is the person: I am justified in believing certain things. What is it that is justified? Me, you, him, her—we are justified in how we have formed our beliefs. There is something odd in the idea that a belief state itself could be justified—just as it is odd to suppose that an action, construed as a bodily movement, could be justified. That is like supposing that a state or act could be reasonable or rational; people are reasonable or rational. Compare: words don’t refer—people do. If I am rational in forming a belief, then we can say derivatively that my belief is rational, but we must not forget that such rationality flows from the epistemic subject. It is the self that rational or irrational, reasonable or unreasonable, justified or unjustified. We can say derivatively that an assertion is justified too, construed as a vocal utterance, but it would be strange to say that a pattern of sound is the primary bearer of justification, not the subject who produces that sound. The canonical form of ascription here is “S is justified in asserting that p”. This is why I am responsible if I lapse from good epistemic practice—not my speech act or my belief. The critic will say to me, “Youwere not justified in believing or asserting that p”. In such a case I need to be more careful, not my beliefs or assertions. It would be a category mistake to criticize my mental states or speech acts—they are not the delinquents.

            This has a bearing on how we talk about verification and falsification in the sciences. It is not that theories, construed as sets of propositions or sentences, are verified or falsified, as if this can take place in a personal vacuum; rather, people are justified in believing certain theories, given the evidence, or in believing the negation of those theories. To say that a theory has been falsified is just to say that people are justified in believing the negation of that theory; theories don’t get to be falsified independently of mental acts by persons. It is not that evidence somehow confronts theories by itself and renders them verified or falsified; the evidence has to go via persons who evaluate that evidence. Scientific theories are verified or falsified only because scientists have justifiably formed various beliefs about them. That is the structure of an epistemic fact: E is evidence for T if and only if E provides a justification for believing T in subjects S. Hence epistemology must be personalized: it cannot just deal in sense data and beliefs or sensory stimuli and behavioral assent—it must recognize persons as indispensable components in the process of justification.  Foundationalism, for example, must be formulated as the doctrine that all justification depends on rational agents being justified in holding a set of foundational beliefs; and coherentism must be formulated as the doctrine that justification consists of rational agents forming their beliefs in a coherent manner. It is not a matter of beliefs per se having solid foundations or cohering with other beliefs; it is a matter of persons basing their beliefs on a foundation or ensuring that their belief systems are coherent. This is the right way to think about the structure of justification—not as something abstracted away from persons. Similarly, when considering skepticism we should ask whether people are justified in believing in the external world or other minds, not whether the corresponding propositions are justified or even whether such beliefs are justified. The skeptical question is whether I am justified in believing in the external world or other minds: am I being rational in holding commonsense beliefs of these kinds? If I am not, that is a fault of mine. The skeptic is criticizing me—I am the one failing to live up to the requirements of rationality. It isn’t that formulating the questions in this way helps to solve them—it may even make them more difficult—but this is conceptually the correct way to do it. Wherever there is justification there is a subject justified.  Epistemology may or may not be naturalized, but it should it personalized.  [1]

  [1] Why has the self not figured more prominently in modern epistemology? I reckon it is because of an assumed empiricism about the nexus of justification: the self has not been amenable to empiricist treatment and is generally regarded with suspicion by empiricists, beginning with Hume. When empiricism began to take a more materialistic form, spearheaded by Quine, the self was even less on the list of approved entities—especially the self as conscious, reflective, and norm-sensitive. Justification began to be conceived as a mere triggering of internal states by physical stimuli, not as a person rationally evaluating evidence. Evidence must be received by an epistemic subject and then used by that subject as a justification for belief or assertion; it doesn’t just feed directly into belief or assertion.

There is something surprising about the Cogito: it is not merely trivially true like, “I think, therefore I have states of mind” or “I think, therefore there is a non-empty set of my thoughts”. What is it that is surprising? Not the claim that I have thoughts, and not the claim that I exist, but the claim that my existence follows from my having thoughts. I take it for granted that I think and that I exist, but I don’t take it for granted that these two facts are logically connected—the Cogito informs me of that connection. That is the point of the Cogito. It is the “therefore” in it that commands interest. It is surprising that the existence of a self should be implicit in acts of thinking—that such acts should require a thing to perform them. For could there not be acts without an actor? Compare the Corporea: “I breathe, therefore I have a body”. I know that I breathe and I know that I have a body, but it is surprising to be told that the former demonstrates the latter—that having a body is logically implicit in acts of breathing. That is, it is surprising that we can infer the existence of a thing that breathes from the mere fact of the existence of breaths. For could there not be events without objects? Descartes invites us to accept that we are thinking things (“substances”) based on the premise that we perform thinking acts—as someone might try to derive bodily things from bodily acts. But the inference in both cases is notoriously questionable: all we can derive logically from acts and events are acts and events, not things that are the subject of such acts and events. We might be committed to a metaphysical theory that recognizes only acts and events, with no objects in the picture, or we might believe in the metaphysical possibility of free-floating acts and events; in neither case will we see a logical connection between the existence of acts or events, on the one hand, and the existence of objects that perform or undergo these acts or events, on the other. We certainly won’t think that we can prove to a skeptic that there are things that think or breathe merely from the fact that there is thinking or breathing (hence Lichtenberg’s objection). Such a proof requires a substantive metaphysical assumption and is certainly not self-evident. So the interesting part of the Cogito is also the most questionable part. Such is philosophy.

            Now consider Hume’s anti-Cogito. Hume invites us to agree that we do not exist, or at least that we have no rational reason to suppose that we do (we might believe it instinctively). The argument for this is that we cannot find the self by looking within: we find only perceptions, thoughts, and feelings, not a self that has them. I know that I have thoughts because I can be conscious of my thoughts introspectively, but I cannot know that I exist by being conscious of myself introspectively—for I do not encounter myself in this way (nor in any other way).  [1] I have thoughts and yet I do not exist (or there is no reason to believe that I do). We might even put Hume’s argument in the form of a deduction: “I think, therefore I do not exist”.  [2] For it is the known existence of my thoughts that reveals by contrast that my self is unknowable: I am not the kind of object of knowledge that my thoughts are—they can be encountered and I cannot. Moreover, for Hume I am rendered redundant once thoughts are introduced: if I have a robust mental life, why do I need to be a thing that has this mental life—isn’t the mental life enough? According to Hume, the self contrasts with thoughts epistemologically, not being knowable as they are; and it is surplus to requirements. Thoughts are therefore not a reason to believe in the self, but a reason to doubt its existence. We can never know the self to exist in the way we know thoughts to exist—by being presented with the self. And there is no other way we could know the self to exist. Thoughts crowd out the self instead of ushering it in.

            Hume’s argument is also surprising. It is certainly surprising to be told that I do not exist, based on the premise that I can’t be encountered in introspection; but this is actually a bad argument—and I don’t think Hume is guilty of it (though many of his readers have been). For it does not follow from the fact that I cannot encounter Xthat X does not exist—that would be to infer an ontological conclusion from an epistemological premise. But Hume’s argument is surprising even without that familiar non sequitur, because it is surprising that the self does not possess the kind of accessibility that thoughts possess: we assume that thoughts can be encountered, and we assume likewise that the self can be, but Hume persuades us that the latter assumption is false. It is surprising to discover that something whose existence we take for granted (rightly so, in my view) is not knowable in the way we naively supposed. The surprise here is analogous to the surprise delivered by Hume’s argument about causation: we assume causation to exist (rightly so, in my view) but are surprised to discover that it cannot be encountered in the perception of causally related objects (because of the imperceptibility of necessary connection). The self similarly eludes encounter—and that is surprising. What Hume’s argument tells us (or purports to) is that we have no reason to believe in the self that is based on the known existence of thoughts, still less on direct experience of the self. Hence it is an anti-Cogito: “I think, but I cannot infer from this that I exist”.

            Both Descartes’ Cogito and Hume’s anti-Cogito rank as paradigms of philosophy: they find (or claim to find) something surprising in even the most familiar and intimately known facts. This tendency to find the surprising in the commonplace is characteristic of philosophy. You can learn a lot about philosophy just by considering these two arguments.  [3]

  [1] Descartes’ argument can be read as conceding Hume’s main point (setting aside chronology), since Descartes never claims that we have direct conscious awareness of the self—hence it must be inferred from things of which we do have such awareness, viz. thoughts. From Hume’s point of view, however, no such argument could ever work, since selves and thoughts are “distinct existences”, so that one never logically implies the other.

  [2] I am here calling “Hume’s argument” an argument that many have derived from Hume—to the effect that there is no such thing as the self. In fact, I don’t think Hume argued this way, concluding only that we have no knowledgeof the self. But I am trying to avoid exegetical questions and focus in on a well-known line of thought.

  [3] The main purpose of this essay is pedagogical: setting Descartes’ argument and Hume’s argument side-by-side, contrasting and comparing. I think this would be a good way to begin an introductory philosophy course: two compelling lines of thought that lead in opposite directions.

Degrees of Determinism

People usually talk about determinism and indeterminism as if it were a binary affair. But there are different strengths of determinism and indeterminism, with some more plausible than others. Let me first define the strongest possible kind of determinism: if a cause from the actual world is repeated in a possible world, it will always produce an effect just like the one produced in the actual world. The cause necessitates the effect, in the strongest sense of necessity. Whenever causes recur there cannot be any variation in the effect produced. Duplicate causes produce duplicate effects as a matter of (metaphysical) necessity. We can compare this to the claim that nothing can follow a given number in the number series but the number that actually follows it (e.g. nothing can follow 3 but 4): a given number determines the number that follows it. Similarly, the premises of a valid argument determine the conclusion in the sense that in no possible world does anything else follow from those premises. We use the word “follow” in each of these cases and the determinist claim is that nothing can follow except what doesfollow. This is stronger than saying that in our universe like causes always produce like effects; it says that in every possible universe the sequence of events is the same as in our universe, given identity of causes. If one billiard ball hits another in our universe and brings about a certain effect, then an exactly alike cause in any possible world will produce an effect of the same type. We might call this “full-strength determinism”.

            But we can dilute this kind of determinism in different ways. We can replace talk of metaphysical necessity with talk of nomological necessity or we can limit determinism to our own universe while remaining agnostic about other possible universes. We can also introduce the notion of partial determinism understood as follows: the properties of the cause don’t fully determine the properties of the effect, but they do partially determine them. Given the cause, the effect must have a certain subset of the properties it has in other instances—though not all. The effect doesn’t have to be exactly alike in all cases involving the same cause (type not token), but it has to be alike in certain respects. Then we can have degrees of determinism fixed by how many properties have to be invariant across cases: is it most properties or many or a few? And which ones have to be invariant from case to case? For example, the impacting billiard ball might have to produce the same linear motion from case to case, but not the same spin or the same noise or the same displacement of air. Maybe some properties will be selected as always present in the effect while others are optional; or it may be held that no particular set of properties must be present. Thus full determinism is rejected but partial determinism is retained—the weakest kind being that at least some effect has to be produced though it may be very different from case to case (the billiard ball has to do something, but what it does is entirely up for grabs).

            Corresponding to degrees of determinism we have degrees of indeterminism. The indeterminist need not be committed to the very strongest form of indeterminism, namely there is no uniformity from case to case. If someone were to claim that nature possesses no uniformity at all, with like causes always producing unlike effects, we would reject that as empirically false: it is simply not the case that billiard ball collisions sometimes cause motion in the struck ball and sometimes cause it to change color and sometimes make it explode and sometimes turn it into an egg. None of this happens, so indeterminism of this kind is obviously false. Still, it is an apparently intelligible view—it might describe a logically possible world. But we can scale back from it as we did with determinism, limiting indeterminism to the possibility that some properties of the effect are not uniform from case to case.  For instance, the exact trajectories of particles may not be determined by the cause, but the cause cannot produce no motion at all or a change of color or an alteration of electric charge. That is, determinism might be partially true but not wholly true; thus indeterminism is only partially true. No one has ever claimed that our universe is subject to full-strength indeterminism; the claim has only been that indeterminism holds in certain limited domains (usually quantum physics and free will). Nor has anyone claimed that there are possible worlds that are subject to indeterminism in every respect: worlds in which identical causes always produce wildly varying effects—from balls moving to balls igniting to balls turning into eggs. I myself find the idea of such a world repugnant to reason—a mere fancy. In any case, it is not what people mean who advocate indeterminism. They typically mean something quite limited, a small breach in the general determinism of nature. They believe in local indeterminism not global indeterminism.

            This raises a question that should receive more attention: if extreme indeterminism is out of the question, why is partial indeterminism deemed acceptable? If nature can be non-uniform in one area, why can’t it be non-uniform in all areas? If it makes sense here, why doesn’t it make sense everywhere? People who say that quantum mechanics shows that the world is not deterministic are speaking sloppily, since all they mean is that certainproperties of quantum effects are not always preserved in the presence of the same cause. But many properties arepreserved, so determinism is true with respect to those properties. No one has ever given any reason for supposing that nothing is determined by the cause, so that any kind of effect can follow the same cause; and such a claim is both factually false and dubiously intelligible. To repeat: it is not true that there is radical variation from case to case, with identical causes generating wildly different effects; and if we try to imagine a world like that, we get something that tests credulity. How could a billiard ball turn another billiard ball into an egg or a thought or a singing nun? Such things are impossible! But if they are impossible, why is it not impossible for the same cause to produce a slightly different effect? If they are impossible because determinism is a condition of possibility, then why can there be even minor violations of determinism? It is as if the indeterminist implicitly understands that his startling doctrine can only be pushed so far before it collapses into absurdity, so he declines to consider pushing it further. We end up with the view that only a very limited indeterminism could be true, on pain of leaving all reality behind. It can only occur in small pockets of the universe. Mostly things are deterministic.

To me this suggests that we should do our best to find alternative explanations of observable phenomena, accepting even local indeterminism with great reluctance. In the case of free will, we should not rush to embrace indeterminism without asking ourselves what we would think of more extreme forms of indeterminism; we should work to develop a view of free will that avoids anything like this.  [1] In the case of quantum mechanics, who knows what to say, but we should be cautious about adopting indeterminism even in this restricted domain—given that we would never accept it more globally. No one thinks, for instance, that the unpredictability of the weather is a good reason to accept meteorological indeterminism; and anyone who thinks it is should be asked whether they think the world is subject to indeterminism through and through. How much of an indeterminist are you are you willing to be? I myself am inclined to accept full-strength determinism, as strong as logical and mathematical determinism (though it is hard to see how that position could be proved); but no sane person is willing to accept the correspondingly strong form of indeterminism (nothing is determined). My point has been that local indeterminism is the same kind of thing as the global kind: if it is intelligible in one place, it ought to be intelligible everywhere. And why should it be true of only certain things and not others? Shouldn’t nature be uniformly indeterminist if it is indeterminist at all? It would be strange if nature were only partially governed by laws, with some parts lawful and others lawless: for example, protons fall under laws but electrons don’t. Could cats be law-governed but not dogs? Could particles and people be subject to indeterminism but nothing else? What makes these things so exceptional? And anyway particles and people are somewhat deterministic even according to indeterminist views—so why aren’t they wholly so? Local indeterminism is an anomalous position given that we must accept that determinism is the general rule.  [2]

  [1] I think that free will entails determinism, so I have no motivation to invoke indeterminism here. It would be nice to show that quantum mechanics likewise entails determinism (!) and is not merely compatible with it.

  [2] The belief in miracles also involves a curious confinement: they happen locally and sporadically, not universally. It is as if people need to believe that nature is not wholly natural—there are pockets of the supernatural in nature. Similarly, the belief in indeterminism is apt to be confined to certain areas, as if the rule of determinism has to have exceptions. The issues are connected inasmuch as miracles will involve breaches of determinism and indeterminism has the look of a miracle (is that the psychological basis of the attraction of indeterminism?). Indeterminism excites our sense of wonder while determinism reminds us of the inescapability of the daily grind.