No abstract

Why do neurons have dendritic spines? This question—the heart of what Yuste calls “the spine problem”—presupposes that why-questions of this sort have scientific answers: that empirical findings can favor or count against claims about why neurons have spines. Here we show how such questions can receive empirical answers. We construe such why-questions as questions about how spines make a difference to the behavior of some mechanism that we take to be significant. Why-questions are driven fundamentally by the effort to understand how some item, such as the dendritic spine, is situated in the causal structure of the world (the causal nexus). They ask for a filter on that busy world that allows us to see a part’s individual contribution to a mechanism, independent of everything else going on. So understood, answers to why-questions can be assessed by testing the claims these answers make about the causal structure of a mechanism. We distinguish four ways of making a difference to a mechanism (necessary, modulatory, component, background condition), and we sketch their evidential requirements. One consequence of our analysis is that there are many spine problems and that any given spine problem might have many acceptable answers.

Until recently, the problem of traumatic brain injury in sports and the problem of performance enhancement via hormone replacement have not been seen as related issues. However, recent evidence suggests that these two problems may actually interact in complex and previously underappreciated ways. A body of recent research has shown that traumatic brain injuries (TBI), at all ranges of severity, have a negative effect upon pituitary function, which results in diminished levels of several endogenous hormones, such as growth hormone and gonadotropin. This is a cause for concern for many popular sports that have high rates of concussion, a mild form of TBI. Emerging research suggests that hormone replacement therapy is an effective treatment for TBIrelated hormone deficiency. However, many athletic organizations ban or severely limit the use of hormone replacing substances because many athletes seek to use them solely for the purposes of performance enhancement. Nevertheless, in the light of the research linking traumatic brain injury to hypopituitarism, this paper argues that athletic organizations' policies and attitudes towards hormone replacement therapy should change. We defend two claims. First, because of the connection between TBI and pituitary function, it is likely many more athletes than previously acknowledged suffer from hormone deficiency and thus could benefit from hormone replacement therapy. Second, athletes' hormone levels should be tested more rigorously and frequently with an emphasis on monitoring TBI and TBI-related issues, rather than simply monitoring policy violations.

Evidence-based medicine (EBM) proponents have argued that mechanistic evidence concerning medical treatments should be considered secondary to evidence derived from randomized controlled trials (RCTs). One common criticism of RCTs is that they often do not yield results that are generalizable to clinical practice, and that for clinical practice application, mechanistic evidence is needed. However, proponents of EBM have argued that mechanistic reasoning is often unreliable and thus not very useful. Here we suggest an important role of mechanistic explanation that has been left out of this discussion entirely, namely, its importance in a patient's decision of whether or not to take certain drugs. We argue that in certain cases, knowing how a treatment works is just as important for the patient as knowing whetherit does. In this paper, we explore how and why giving patients mechanistic information can be an important factor in obtaining informed consent for medical treatment, focusing on the example case of hormonal contraceptives.

Many transhumanists see their respective movement as being rooted in ancient ethical thought. However, this alleged connection between the contemporary transhumanist doctrine and the ethical theory of antiquity has come under attack. In this paper, we defend this connection by pointing out a key similarity between the two intellectual traditions. Both traditions are committed to the “radical transformation thesis”: ancient ethical theory holds that we should assimilate ourselves to the gods as far as possible, and transhumanists hold that we should enhance ourselves beyond the physical and intellectual parameters of being human so as to become posthuman. By considering the two views in tandem, we develop an account of the assimilation directive that is palatable to contemporary readers and provide a view of posthumanism worth wanting.