Alyscia Smith

We have synthesized a 582,970-base pair Mycoplasma genitalium genome. This synthetic genome, named M. genitalium JCVI-1.0, contains all the genes of wild-type M. genitalium G37 except MG408, which was disrupted by an antibiotic marker to block pathogenicity and to allow for selection. To identify the genome as synthetic, we inserted "watermarks" at intergenic sites known to tolerate transposon insertions. Overlapping "cassettes" of 5 to 7 kilobases (kb), assembled from chemically synthesized oligonucleotides, were joined by in vitro recombination to produce intermediate assemblies of approximately 24 kb, 72 kb ("1/8 genome"), and 144 kb ("1/4 genome"), which were all cloned as bacterial artificial chromosomes in Escherichia coli. Most of these intermediate clones were sequenced, and clones of all four 1/4 genomes with the correct sequence were identified. The complete synthetic genome was assembled by transformation-associated recombination cloning in the yeast Saccharomyces cerevisiae, then isolated and sequenced. A clone with the correct sequence was identified. The methods described here will be generally useful for constructing large DNA molecules from chemically synthesized pieces and also from combinations of natural and synthetic DNA segments. 10.1126/science.1151721.

In her careful consideration of my book, The Problem of Perception, Susanna Siegel highlights what she takes to be a number of shortcomings in the work. First, she suggests that a sense-datum theorist has two options—what she calls the “complex sense-data option” and the “two-factor option”—that survive the argument of my book unscathed. I consider these two options in the first two sections of this reply. Secondly, she criticizes my suggestion that there are three and only three basic and independent sources of perceptual consciousness: an issue I take up in my third section. Thirdly, she expresses reservations about my response to the argument from hallucination. In particular, she argues that the phenomenological considerations on which I put so much weight cannot settle the fundamental issue here. I address this criticism in the fourth section of this reply. Finally, she spends a certain amount of time discussing the notion of a “veridicality-relevant property”, a topic to which I devote the concluding section of this reply.

It is argued that Husserl was an “externalist” in at least one sense. For it is argued that Husserl held that genuinely perceptual experiences—that is to say, experiences that are of some real object in the world—differ intrinsically, essentially and as a kind from any hallucinatory experiences. There is, therefore, no neutral “content” that such perceptual experiences share with hallucinations, differing from them only over whether some additional non-psychological condition holds or not. In short, it is argued that Husserl was a “disjunctivist”. In addition, it is argued that Husserl held that the individual object of any experience, perceptual or hallucinatory, is essential to and partly constitutive of that experience. The argument focuses on three aspects of Husserl’s thought: his account of intentional objects, his notion of horizon, and his account of reality