This paper is based on the comments I gave to Alfred Mele regarding his original Zygote Argument during my presentation at a small workshop on manipulation arguments in Budapest back in 2012. After those comments, Mele changed the conclusion of his original Zygote Argument and redefined 'incompatibilism' so that it would refer to the conclusion of his new Zygote Argument (Mele 2013+). Yet, over the last decade, Mele has made no comment in print about the changes he (...) made nor the invalidity objection that led to them. To my knowledge, Mele has only mentioned this 2015 paper once: in the context of defending his non-explanatory definition of 'incompatibilism' at the opening of Aspects of Agency (p. 6, n. 4), Mele draws his readers' attention to just *just this paper* as a place where they'll find the type of nonstandard/nontraditional definition of 'incompatibilism' that he rejects. If Mele had a general concern about unusual definitions of 'incompatibilism', he could have just as easily named almost any leading figure in free will for this purpose (since most reject the non-explanatory definition he now endorses). But for some reason, Mele thought an unemployed junior researcher should be singled out as an example. Moreover, if Mele were genuinely interested in helping his readers understand the ambiguity of terms like 'compatibilism' and 'incompatibilism' it is a mystery that he referenced a paper in which nothing of substance hung on the definitions given to these terms when he might have instead pointed them to my OTHER 2015 paper in which the MAIN AIM of the paper is to expose the difficulties facing anyone who wants to define the terms 'compatibilism' and 'incompatibilism' in a way that everyone will accept (including a critique of the definitions that Mele has adopted). By all appearances, Mele's aim was to give readers the false impression that my working definition of 'incompatibilism' played some role in my charge that his argument is invalid (which it doesn't, given that the term doesn't appear in either the premises or conclusion of that argument). In this paper, I simply use the invalidity of the simple 2-premise Zygote Argument to make a series of more philosophically significant points (e.g. regarding the dialectical structure of the free-will debate, the role of best-explanation reasoning, and to develop the first-ever "master manipulation argument"). Mele pays no attention to my answer to the "Now What?" question in this paper, even though that answer was the paper's main point. For those interested in a more recent discussion of how the logical and metaphilosophical observations made in this paper have helped to move the free-will debate forward, I suggest my contributions to the Wiley-Blackwell Companion to Free Will (Intro and Chapter 4, 2023) and my paper "Free Will, Self-Creation, and the Paradox of Moral Luck" (2019). (shrink)

In “The Zygote Argument is Invalid: Now What?” (2015), Kristin Mickelson published an objection to the Zygote Argument that she first presented in 2012 as workshop comments on a draft of Mele's "Manipulation, Moral Responsibility, and Bullet-Biting" (2013). Assuming that the phrase "determinism precludes free will" means something like determinism-related causal factors are what prevent people from acting freely when determinism is true, Mele's original Zygote Argument was invalid. At the workshop, Mickelson presented Mele with two options (...) to address the problem, a premise-preserving option and a conclusion-preserving option. That is, Mele could change the conclusion of the original argument to the negative, non-explanatory thesis entailed by its original two premises, or find a way to add premises that would support the positive, explanatory conclusion of the original argument (which, notably, is the conclusion that Pereboom supports using best-explanation reasoning in his Four-Case Argument). Mickelson used this as an opportunity to explain the key contribution that best-explanation reasoning makes to manipulation arguments -- and why the best variant of the manipulation argument might conclude that incompatibilism is FALSE. In response to Mickelson's objection, Mele changed the conclusion of the argument before "Manipulation, Moral Responsibility, and Bullet-Biting" went to print, choosing Mickelson's proposal to change its conclusion over the suggestion to change its premises. However, Mele failed to mention Mickelson's invalidity objection in print and that he changed the conclusion of his argument as a direct response to it; nor did Mele mention the costs that Mickelson outlined for the premise-preserving solution that he adopted or the benefits of a conclusion-preserving solution. At the same time, Mele began using the term 'incompatibilism' to pick out the negative, non-explanatory claim supported by the newly revised Zygote Argument--and also started to claim (without providing evidence) that those who use the term 'incompatibilism' to denote the explanatory claim deterministic causal factors *make it the case* that no one acts freely when determinism is true" is guilty of using the term in a nonstandard and nontraditional way that he had "never had any use for"--failing to mention that he clearly used the term in this explanatory sense in his 2005 critique of the Four-Case Argument, which is to be expected give that Derk Pereboom uses the explanatory definition (as do Kadri Vihvelin, Carolina Sartorio, and *most* other contributors to the free-will literature). In THIS reply essay, Mickelson responds to an attempt by Gabriel De Marco (FSU, advisor Alfred Mele) to defend the original Zygote Argument from Mickelson's 2012/2015 critique. Unfortunately, both of De Marco's proposed "solutions" are non-starters. The first is a non-starter because De Marco merely repeats the premise-preserving solution that Mickelson offered to Mele in 2012 and that Mele adopted in print in 2013. In other words, De Marco took credit for the premise-preserving solution to the invalidity objection that Mickelson developed (although he does *redescribe* Mickelson's solution in his own idiosyncratic jargon) and Mele had already adopted in print. De Marco's second solution is a non-starter because it is constituted by a patently invalid argument. Contrary to De Marco's proposal, it's not true that the conjunction of possibilism and incompossibilism deductively entails the positive, diagnostic claim that deterministic causal factors beyond one's control preclude (destroy, undermine, is antagonistically relevant to) free will when determinism is true. *My thanks to the editors of Philosophia for publishing this reply when PhilStudies would not. (shrink)

In this paper I defend the view that a zygote is a human from the fission objection that is widely thought to be decisive against the view. I do so, drawing upon a recent discussion of this issue by John Burgess, by explaining in detail the metaphysical position the proponent of the view should adopt in order to rebut the objection.

In some quarters, it is held that Anscombe proved that a zygote is not a human being on the basis of an argument involving the possibility of identical twins, but there is surprisingly little agreement on what her argument is supposed to be. I criticize several extant interpretations, both as interpretations of Anscombe and as self-standing arguments, and offer a different understanding of her conclusion on which the non-specificity of creation processes and their goals is at issue.

Alfred Mele’s zygote argument is widely considered to be the strongest version of the manipulation argument against compatibilism (about free will and determinism). Opponents have focused largely on the first of its two premises and on the overall dialectic. My focus here will be on the underlying thought experiment—the Diana scenario—and on the second premise of the argument. I will argue that reflection on the Diana scenario shows that the second premise does not hold, and we will see that (...) my objection to the second premise helps to defend the claim that manipulation arguments face, in general, a dilemma. (shrink)

It is no longer possible to claim that the biological characteristics of the future adult are already determined at conception. After all, a zygote may develop into a hydatidiform mole rather than into a human being. The development of an individual human person is determined by genetically and nongenetically coded molecules within the embryo, together with the influence of the maternal environment. Consequently, it is an error to regard the zygote's chromosomal (and other) DNA as sufficient to determine (...) the uniqueness of the future individual. (shrink)

John and Mary have fully consensual sex, but they do not want to have a child, so they use contraception with the intention of avoiding pregnancy. Unfortunately, although they used the contraception in the way in which it is supposed to be used, Mary has become pregnant. The couple decides to have the baby, whom they name ‘Ernie’. Now we fill in the story a bit. The universe is causally deterministic, and 30 years later Ernie performs some action A and (...) thereby brings about event E. We also stipulate that Ernie meets plausible compatibilist conditions for acting freely . That is, we suppose that there are no uncontroversially freedom- and responsibility-undermining conditions present in the context in which Ernie performs A, and, further, that Ernie meets plausible compatibilist conditions for acting freely. Let us say, for example, that one adopts the theory according to which the freedom-relevant condition on moral responsibility is that the agent exhibits ‘guidance control’ of his action and . On this approach, one acts freely in so far as one acts from one's own, suitably reasons-responsive mechanism. We can then simply stipulate that, in the relevant context, Ernie acts from his own, suitably reasons-responsive mechanism . If one prefers a different set of compatiblist-friendly conditions for acting freely, one can simply stipulate that Ernie meets them; indeed, the plausible compatibilist-friendly conditions seem to be compatible with each other, and thus Ernie could presumably meet all of them in the relevant context. In such a case, and given that the epistemic condition on acting freely and moral responsibility is met, I am inclined to say that Ernie …. (shrink)

Alfred Mele’s zygote argument for incompatibilism is based on a case involving an agent in a deterministic world whose entire life is planned by someone else. Mele’s contention is that Ernie (the agent) is unfree and that normal determined agents are relevantly similar to him with regards to free will. In this paper, I examine four different ways of understanding this argument and then criticize each interpretation. I then extend my criticism to manipulation arguments in general. I conclude that (...) the zygote argument is no threat to compatibilism. (shrink)

This article is a response by the author of Defending Life, Francis Beckwith, to Kevin Corcoran’s critical review of that book. In his review Corcoran maintains that Beckwith provides only a “typical” genetic code argument for the zygote’s individual humanity, and that Beckwith fails to show that there exists an individual human organism that subsists from conception and develops into a mature version of itself. Beckwith argues that Corcoran is mistaken on both counts.

Zygotic gene activation (ZGA) is the critical event that governs the transition from maternal to embryonic control of development. In the mouse, ZGA occurs during the 2‐cell stage and appears to be regulated by the time following fertilization, i.e. a zygotic clock, rather than by progression through the first cell cycle. The onset of ZGA must depend on maternally inherited proteins, and post‐translational modification of these maternally derived proteins is likely to play a role in ZGA. Consistent with this prediction (...) is that protein phosphorylation catalyzed by the cAMP‐dependent protein kinase is involved in ZGA and that protein synthesis is not required for ZGA. Recent results suggest that ZGA may occur earlier than previously thought, i.e. not during the 2‐cell stage, but rather in G2 of the 1‐cell embryo. Thus ZGA may comprise a period of minor gene activation in the 1‐cell embryo that is followed by a period of major gene activation in the 2‐cell embryo. Following ZGA, the expression of constitutively activated genes may require an enhancer. (shrink)

This paper re-examines the question of whether quirks of early human foetal development tell against the view (conceptionism) that we are human beings at conception. A zygote is capable of splitting to give rise to identical twins. Since the zygote cannot be identical with either human being it will become, it cannot already be a human being. Parallel concerns can be raised about chimeras in which two embryos fuse. I argue first that there are just two ways of (...) dealing with cases of fission and fusion and both seem to be available to the conceptionist. One is the Replacement View according to which objects cease to exist when they fission or fuse. The other is the Multiple Occupancy View – both twins may be present already in the zygote and both persist in a chimera. So, is the conceptionist position tenable after all? I argue that it is not. A zygote gives rise not only to a human being but also to a placenta – it cannot already be both a human being and a placenta. Neither approach to fission and fusion can help the conceptionist with this problem. But worse is in store. Both fission and fusion can occur before and after the development of the inner cell mass of the blastocyst – the entity which becomes the embryo proper. The idea that we become human beings with the arrival of the inner cell mass leads to bizarre results however we choose to accommodate fission and fusion. (shrink)

In a recent paper, Kristin Mickelson argues that Alfred Mele’s Zygote Argument, a popular argument for the claim that the truth of determinism would preclude free action or moral responsibility, is not valid. This sort of objection is meant to generalize to various manipulation arguments. According to Mickelson, the only way to make such arguments valid is to supplement them with an argument that is an inference to the best explanation. In this paper, I argue that there are two (...) other ways in which the proponent of such manipulation arguments can modify their argument, neither of which requires an inference to the best explanation. I then briefly consider and respond to a worry with one of these proposed solutions. (shrink)

The usual way for new cells to come into being is by division of old cells. So the zygote, which is a—new—single cell formed from two, the sperm and ovum, is an exception. Textbooks of human genetics usually say that this new cell is beginning of a new human individual. What this indicates is that they suddenly forget about identical twins.

Many people believe that human beings begin to exist with the emergence of the 1-cell zygote at fertilization. I present a novel argument against this belief, one based on recently discovered facts about human embryo development. I first argue that a human zygote is developmentally plastic: A zygote that naturally develops into a singleton (i.e., develops into exactly one infant/adult without twinning) might have naturally developed into a numerically different singleton. From this, I derive the conclusion that (...) a human infant or adult is numerically distinct from the zygote she came from and so did not begin to exist at fertilization. This implies that a zygote does not have a “future like ours” and strongly suggests that it is not a human being. (shrink)

Zygote cytokinesis produces two symmetric blastomeres, which contain one copy of each parental genome. Contrary to this dogma, we recently discovered that mammalian zygotes can spontaneously segregate entire parental genomes into different blastomeres and coined this novel form of genome segregation heterogoneic division. The molecular mechanisms underlying the emergence of blastomeres with different parental genomes during the first mitotic cycle remain to be elucidated. Here, we speculate on which parental genome asymmetries could provide a mechanistic foundation for these remarkable (...) zygote divisions. In reviewing the field and considering our findings, we revisit the architecture of the first zygotic metaphase by invoking asymmetric interactions between the mitotic spindle and the parental kinetochores. We also speculate on how asynchronous parental cell cycles can be a source of heterogoneic zygote divisions through the formation of parental genome private spindles. (shrink)

In this paper I argue that the distinction between moral responsibility and autonomy can illuminate various debates about the Zygote Argument. Having made this distinction, one can see how these manipulation arguments are unsuccessful. Building on previous work, I also argue that this distinction can provide a framework for understanding other important work in agency theory, including that of Harry Frankfurt and Gary Watson.

Think of the last thing someone did to you to seriously harm or offend you. And now imagine, so far as you can, becoming fully aware of the fact that his or her action was the causally inevitable result of a plan set into motion before he or she was ever even born, a plan that had no chance of failing. Should you continue to regard him or her as being morally responsible—blameworthy, in this case—for what he or she did? (...) Many have thought that, intuitively, you should not. Recently, Alfred Mele has employed this line of thought to mount what many have taken to be a powerful argument for incompatibilism: the “Zygote Argument”. However, in interesting new papers, John Martin Fischer and Stephen Kearns have each independently argued that the Zygote Argument fails. As I see it, the criticisms of Fischer and Kearns reveal some important questions about how the argument is meant to be—or how it would best be—understood. Once we make a slight (but important) modification to the argument, however, I think we will be able to see that the criticisms of Fischer and Kearns do not detract from its substantial force. (shrink)

The usual way for new cells to come into being is by division of old cells. So the zygote, which is a—new—single cell formed from two, the sperm and ovum, is an exception. Textbooks of human genetics usually say that this new cell is beginning of a new human individual. What this indicates is that they suddenly forget about identical twins.

Agents have no control over the formation of their own zygote. Others may do. According to a well-known argument, the so-called Zygote Argument for incompatibilism, these facts, together with a prima facie plausible further assumption, are sufficient to prove that human agents cannot be responsible for their actions if they live in a deterministic universe. This paper argues that the lack of agents’ control over the constitution of their own zygote can undermine their responsibility only in exceptional (...) conditions and that the occurrence or non-occurrence of those conditions has nothing to do with the truth or falsity of determinism. What undermines agents’ responsibility in the situations described by the Zygote Argument is the occurrence of some specific initial conditions which may render the manipulation of agents’ behaviour possible, and not the truth of determinism. (shrink)

That the soul of a human person is infused at conception is a metaphysical claim. But given its traditional articulation, it has the empirical consequence that the zygote must have a substantial continuity with the adult person, a continuity which is already determined at conception. This empirical consequence is contradicted by the fact that the zygote may become a hydatidiform mole, or several persons. The metaphysical claim is falsified by the facts. Keywords: abortion, information capacity, metaphysical account, person, (...) zygote CiteULike Connotea Del.icio.us What's this? (shrink)

Manipulation arguments that start from the intuition that manipulated agents are neither free nor morally responsible then conclude to that free will and moral responsibility are incompatible with determinism. The Zygote argument is a special case of Manipulation argument in which the manipulation intervenes at the very conception of the agent. In this paper, I argue that the Zygote argument fails because (i) very few people share the basic intuitions the argument rests on, and (ii) even those who (...) share this intuition do so for reasons that are unrelated to determinism. Rather, I argue that intuitions about the Zygote argument (and Manipulation arguments in general) are driven by people's intuitions about the deep self, as shown by the fact that intuitions about manipulated agents depend on the moral value of the agent's behavior. (shrink)

I consider the argument, thought to clinch the moral case for use of a human embryo solely as a means, that only a human individual can be a person, because it can happen at any time before formation of the primitive streak that an embryo splits into monozygotic twins, no embryo in which the primitive streak has not formed is a human individual, and therefore no embryo in which the primitive streak has not formed is a person. I explore the (...) following proffered arguments for : indivisibility is a necessary condition of individuality, nonidentity of an embryo with successor twins impugns the embryo’s individuality, and totipotency of an embryo’s constituents is inconsistent with the embryo’s being a human individual. These arguments are tested and found wanting; so too is an alternative to , the argument that indivisibility is intrinsic to personhood. Whereupon is unsustained. In search of ways to rehabilitate the nonindividuation argument, I canvass alternative metaphysical views and inquire further into biological individuality, but find that the argument cannot be saved. I conclude by analyzing where this leaves matters concerning the morality of embryo use. (shrink)

I consider the argument, thought to clinch the moral case for use of a human embryo solely as a means, that only a human individual can be a person, because it can happen at any time before formation of the primitive streak that an embryo splits into monozygotic twins, no embryo in which the primitive streak has not formed is a human individual, and therefore no embryo in which the primitive streak has not formed is a person. I explore the (...) following proffered arguments for : indivisibility is a necessary condition of individuality, nonidentity of an embryo with successor twins impugns the embryo’s individuality, and totipotency of an embryo’s constituents is inconsistent with the embryo’s being a human individual. These arguments are tested and found wanting; so too is an alternative to, the argument that indivisibility is intrinsic to personhood. Whereupon is unsustained. In search of ways to rehabilitate the nonindividuation argument, I canvass alternative metaphysical views and inquire further into biological individuality, but find that the argument cannot be saved. I conclude by analyzing where this leaves matters concerning the morality of embryo use. (shrink)

In Free Will and Luck, Mele presents a case of an agent Ernie, whose zygote was intentionally designed so that Ernie A-s in 30 years, bringing about a certain event E. Mele uses this case of original design to outline the zygote argument against compatibilism. In this paper I criticize the zygote argument. Unlike other compatibilists who have responded to the zygote argument, I contend that it is open to the compatibilist to accept premise one, that (...) Ernie does not act freely and is not morally responsible for anything he does. I argue that compatibilists should deny premise two. Diana’s effective intention to create Ernie’s zygote such that Ernie A-s in 30 years and her intervention to bring about his A-ing mark a significant difference between Ernie and normal agents in a deterministic universe with regard to how their zygotes were created that affects whether those agents act freely and are morally responsible for so acting. (shrink)

Patrick Todd has recently fashioned a novel argument for incompatibilism, the Moral-Standing Zygote Argument. Todd considers much-discussed cases in which a manipulator causes an agent in a deterministic scenario to act morally wrongly from compatibilist-friendly conditions for freedom and moral responsibility. The manipulator, Todd contends, does not have the standing to blame the manipulated agent, and the best explanation for this is that incompatibilism is true. This is why the manipulated agent is not blameworthy. In this paper, I counter (...) Todd on behalf of the compatibilist, arguing that the best explanation for the manipulator's lack of moral standing to blame is due to the manipulator's intending to cause the manipulated agent to do wrong. (shrink)

Annual changes in twinning and triplet rates by zygosity were investigated in eight countries during the period 19721999.

Don Marquis has argued that abortion is immoral because it deprives the fetus of a "future like ours." But Marquis's argument fails by incorrectly assuming that a zygote and the late-term fetus with which it is physically continuous are numerically identical. In fact, the identity of a prebirth human (PBH) across gestation is indeterminate, such that it is determinately morally permissible to destroy an early-term PBH and determinately immoral to destroy a late-term PBH. Beginning at some indeterminate point during (...) gestation and ending at some indeterminate point later in gestation, destroying a PBH is neither determinately morally permissible nor determinately immoral. (shrink)

A number of philosophers maintain that the destruction of an embryo in the first 2 weeks after fertilization is not morally problematic as it is metaphysically impossible for any human organism to then have existed. We contend that the typical adult human organism was once a zygote so there is no metaphysical shortcut to justify early abortion. We show that five arguments against human organisms ever having been zygotes fail. All of the arguments have to do with one variant (...) or another of the zygote or early embryo dividing. They do not provide any reason to believe that since some adult organisms are not identical to zygotes due to earlier divisions, none could have been. (shrink)

Early embryogenesis of Caenorhabditis elegans provides a striking example of the generation of polarity and the partitioning of cytoplasmic factors according to this polarity. Microfilaments (MFs) appear to play a critical role in these processes. By visualizing the distribution of MFs and by studying the consequences of disrupting MFs for short, defined periods during zygote development, we have generated some new ideas about when and how microfilaments function in the zygote.

W Deklaracji o przerywaniu ciąży z 1974, Kościół Katolicki argumentuje, że zygota jest człowiekiem ponieważ posiada ludzki genotyp. Artykuł przedstawia logiczną analizę tej argumentacji. Pokazuje, że argumentacja ta jest w dużym stopniu wadliwa. Tomizm pełni tu funkcję uprawo-mocnienia. Entymematyczne założenia tomistyczne są niezbędne, by w ogóle możliwe było przejście od przesłanek do wniosku. Okazuje się ponadto, że argumentacja ta zakłada tomistyczną interpretację pojęć biologicznych, która jest niezgodna ze współczesną wiedzą biologiczną. Twierdzenie zawarte w Deklaracji nie zostało więc skutecznie uargumentowane na (...) gruncie biologii, a wręcz wydaje się, że biologia je wyklucza. Jest ono możliwe jedynie jako twierdzenie metafizyczne i wyłącznie na gruncie pewnych metafizyk. (shrink)

A little-discussed aspect of the “conservative” position on abortion involves the claim that human beings exist at all stages of gestation — that even the human fertilized ovum is a human being. There are good reasons of both a practical and theoretical nature why this particular idea has received so little attention in the abortion controversy. On the practical side there is the fact that zygotes are rarely if ever the subjects of abortion decisions; and on the theoretical side, there (...) is the prima facie implausibility of the idea itself — an implausibility stemming from the fact that human zygotes possess none of the features that distinguish clear-cut examples of human beings from other living things.I would like to suggest, however, that there are good reasons — again both practical and theoretical — for examining with some care the idea that human zygotes are human beings. For even if this idea is not central to the abortion controversy, it has clear relevance to the morality of using intrauterine devices as a means of procreation control. (shrink)

Centrosomes are the main microtubule organizing centers in animal cells. In particular during embryogenesis, they ensure faithful spindle formation and proper cell divisions. As metazoan centrosomes are eliminated during oogenesis, they have to be reassembled upon fertilization. Most metazoans use the sperm centrioles as templates for new centrosome biogenesis while the egg's cytoplasm re-prepares all components for on-going centrosome duplication in rapidly dividing embryonic cells. We discuss our knowledge and the experimental challenges to analyze zygotic centrosome reformation, which requires genetic (...) experiments to enable scrutinizing respective male and female contributions. Male and female knockout animals and mRNA injection to mimic maternal expression of centrosomal proteins could point a way to the systematic molecular dissection of the process. The most recent data suggest that timely expression of centrosome components in oocytes is the key to zygotic centrosome reformation that uses male sperm as coordinators for de novo centrosome production. Centrosome reformation at fertilization is essential for metazoan development. It requires a complicated interplay of sperm centrioles and the cytoplasm of the oocyte, which has eliminated its centrioles during oogenesis. The male centrioles launch centrosome duplication using female centrosome proteins for the first metazoan cell divisions. (shrink)

I consider, and rebut, the argument from "twinning" - that zygotes can't be considered human individuals as two or more such individuals could be (sometimes are) produced from one zygote.

"The Manipulation Argument has recently taken center stage in the free-will debate, yet little else can be said of this newcomer that is uncontroversial. At present, even the most fundamental elements of the Manipulation Argument--its structure, conclusion, and target audience--are a matter of dispute. As such, we cannot begin, as we ideally would, with a simple and relatively uncontroversial overview of the argument. Instead, clarifying the debate over the basic structure and general conclusion of the Manipulation Argument will be our (...) goal." -/- UPDATE: I now refer to an isolated objection to the counterexample step as a hardline reply, an isolated attack on the generalization step a softline reply, and an isolated response to the explanation step as an "al dente" reply. Al dente replies have been given in Mele's 2005 critique of the Four-Case Argument and my 2015 (2012) critique of Mele's Zygote Argument. I also now refer to a manipulation argument which has a generalization step that concludes to impossibilism and an explanation step which proposes an explanation for the impossibility of free will as a "Master Manipulation Argument" (examples of master manipulation arguments include Mickelson 2015 and 2019). (shrink)

When a human being comes into existence is crucial in bioethics. Conceptionism is the view that a human being comes into existence at conception. The twinning argument is an influential objection to this view. All versions of the twinning argument rely on a metaphysics of material objects, namely, endurantism. Given this, a strategy for defending conceptionism against the twinning argument is to deny endurantism and adopt an alternative metaphysics of material objects. A version of this strategy which has been debated (...) in this journal is to adopt perdurantism, or the ‘multiple occupancy view’, on which monozygotic twins share the zygote region as a temporal part. We present a novel version of this strategy: conceptionists can evade the twinning argument by adopting an exdurantist metaphysics of material objects. We suggest reasons for thinking that this is a plausible and, indeed, preferable way for conceptionists to avoid the twinning argument. (shrink)

Alfred Mele has presented the Zygote Argument as a challenge to compatibilism. In previous work I have offered a critique of Mele’s first premise. Patrick Todd, Neal Tognazzini, and Derk Pereboom have offered an alternative interpretation of the argument, substituting for. Here I offer a critical evaluation of this strategy, and in the process I seek to understand the deep structure of the Zygote Argument.

The view that human beings begin to exist at fertilization (namely conceptionism) faces a serious challenge from the twinning argument, that identical twins coming from the same zygote must be numerically distinct from the zygote and so did not exist at fertilization. Recently, some philosophers have claimed that the twinning argument rests on a particular metaphysical theory of persistence, namely endurantism, on which a human being, for example, is wholly present at every moment of her existence. And we (...) can easily refute the argument, they claim, by employing perdurantism or exdurantism, according to which a human being is a temporally extended entity with temporal parts or a momentarily existing stage who has other momentarily existing stages as counterparts. I argue that such claims are mistaken. The twinning argument does not rest on endurantism and can be formulated in terms of perdurantism to provide a good reason for perdurantists to reject conceptionism. And exdurantism does not have any advantage in defending conceptionism either, for it already concedes more than what the twinning argument aims to show. (shrink)

The germ track is the cellular path by which genes are transmitted to future generations whereas somatic cells die with their body and do not leave direct descendants. Transposable elements (TEs) evolve to be silent in somatic cells but active in the germ track. Thus, the performance of most bodily functions by a sequestered soma reduces organismal costs of TEs. Flexible forms of gene regulation are permissible in the soma because of the self‐imposed silence of TEs, but strict licensing of (...) transcription and translation is maintained in the germ track to control proliferation of TEs. Delayed zygotic genome activation (ZGA) and maternally inherited germ granules are adaptations that enhance germ‐track security. Mammalian embryos exhibit very early ZGA associated with extensive mobilization of retroelements. This window of vulnerability to retrotransposition in early embryos is an indirect consequence of evolutionary conflicts within the mammalian genome over postzygotic maternal provisioning. (shrink)