Vision

Why do things look to us as they do? This question, formulated by psychologist Kurt Koffka, identifies the main problematic of vision science. Consider looking at a black cat. We tend to see both the cat and its colour as the same at different times. Despite the ease with which this perception occurs, the process by which we perceive is fairly complex. The initial stimulation that gives rise to seeing, consists in a pattern of light that projects on the retina – a light-sensitive layer of the eye. The so-called ‘retinal image’ is a two-dimensional projection that does not correspond in any obvious manner to the way things look. It is not three-dimensional, coloured and shaped in a similar fashion to the objects of our experience. Indeed the light projected from objects is not just different from what we see, it is also both continuously changing and ambiguous. Because the cat moves around, the light it reflects changes from moment to moment. The cat’s projection on the retina correspondingly changes in size. We do not, however, see the cat as changing in size. We tend to see it as size-constant and uniformly coloured through time. How do we explain this constancy? Along similar lines, the cat’s white paws cause on the retina a patch of light that differs in intensity from the rest. This patch could also be caused by a change in illumination. A black surface illuminated very brightly can look like a white surface illuminated very dimly. This means that the light hitting the retina from the paws is underdetermined – it does not uniquely specify what is present. But, again, we tend to see the paws as consistently white. We do not see them as shifting from being white to being black, but illuminated brightly. How do we explain this stability? A central aim of theories of vision is to answer these questions. The science that attempts to address these queries is interdisciplinary. Traditionally, philosophical theories of vision have influenced psychological theories and vice versa. The collaboration between these disciplines eventually developed into what is now known as cognitive science. Cognitive science includes – in addition to philosophy and psychology – computer science, linguistics and neuroscience. Cognitive scientists aim primarily to understand the process by which we see. Philosophers are interested in this topic particularly as it connects to understanding the nature of our acquaintance with reality. Theories of vision differ along many dimensions. Giving a full survey is not possible in this entry. One useful difference is whether a theory presumes that visual perception involves a psychological process. Psychological theories of vision hold that in achieving perception – which is itself a psychological state – the organism uses other psychological material. Opponents of psychological theories prefer to make reference to physiological, mechanical and neurophysiological explanations.

Split brains

The largest fibre tract in the human brain connects the two cerebral hemispheres. A ‘split-brain’ surgery severs this structure, sometimes together with other white matter tracts connecting the right hemisphere and the left. Split-brain surgeries have long been performed on non-human animals for experimental purposes, but a number of these surgeries were also performed on adult human beings in the second half of the twentieth century, as a medical treatment for severe cases of epilepsy. A number of these people afterwards agreed to participate in ongoing research into the psychobehavioural consequences of the procedure. These experiments have helped to show that the corpus callosum is a significant source of interhemispheric interaction and information exchange in the ‘neurotypical’ brain. After split-brain surgery, the two hemispheres operate unusually independently of each other in the realm of perception, cognition, and the control of action. For instance, each hemisphere receives visual information directly from the opposite (‘contralateral’) side of space, the right hemisphere from the left visual field and the left hemisphere from the right visual field. This is true of the normal (‘neurotypical’) brain too, but in the neurotypical case interhemispheric tracts allow either hemisphere to gain access to the information that the other has received. In a split-brain subject however the information more or less stays put in whatever hemisphere initially received it. And it isn’t just visual information that is confined to one hemisphere or the other after the surgery. Rather, after split-brain surgery, each hemisphere is the source of proprietary perceptual information of various kinds, and is also the source of proprietary memories, intentions, and aptitudes. Various notions of psychological unity or integration have always been central to notions of mind, personhood, and the self. Although split-brain surgery does not prevent interhemispheric interaction or exchange, it naturally alters and impedes it. So does the split-brain subject as a whole nonetheless remain a unitary psychological being? Or could there now be two such psychological beings within one human animal – sharing one body, one face, one voice? Prominent neuropsychologists working with the subjects have often appeared to argue or assume that a split-brain subject has a divided or disunified consciousness and even two minds. Although a number of philosophers agree, the majority seem to have resisted these conscious and mental ‘duality claims’, defending alternative interpretations of the split-brain experimental results. The sources of resistance are diverse, including everything from a commitment to the necessary unity of consciousness, to recognition of those psychological processes that remain interhemispherically integrated, to concerns about what the moral and legal consequences would be of recognizing multiple psychological beings in one body. On the other hand underlying most of these arguments against the various ‘duality’ claims is the simple fact that the split-brain subject does not appear to be two persons, but one – and there are powerful conceptual, social, and moral connections between being a unitary person on the one hand and having a unified consciousness and mind on the other.

Equality of opportunity

Equality of opportunity is a political ideal according to which participants in some cooperative systems should possess equal access to some advantages at some point in time. According to this ideal, distributive outcomes (e.g., of income, welfare, functionings) should not be fixed in advance, but should result from processes that treat all people equally. Equality of opportunity is an egalitarian ideal, but it focuses on the means by which people acquire advantages, rather than on outcomes. Diverse conceptions of equality of opportunity are distinguished by their different accounts of what it means to possess an equal opportunity, which sorts of advantages people ought to have an equal opportunity to acquire, and which kinds of cooperative activities ought to be regulated by this ideal. In particular, advocates of equality of opportunity disagree about whether equality of opportunity requires only a prohibition on discrimination (e.g., in employment), or whether it also requires efforts to mitigate the influences of some background conditions (e.g., family social status) on distributive outcomes. They also disagree about whether people ought to have an equal opportunity to acquire welfare, resources, functionings, or some combination of these kinds of goods. Finally, advocates of equality of opportunity disagree about whether this ideal should regulate individual choices or only institutional arrangements, and whether it applies only among members of the same society. The concept of equality of opportunity has widespread support across the political spectrum, and therefore most of the critical literature offers objections to particular conceptions of this ideal, rather than to the broader concept of equality of opportunity.

Epistemic value

Epistemic value is a kind of value possessed by knowledge, and perhaps other epistemic goods such as justification and understanding. The problem of explaining the value of knowledge is perennial in philosophy, going back at least as far as Plato’s Meno. One formulation of the problem is to explain why and in what sense knowledge is valuable. Another version of the problem is to explain why and in what sense knowledge is more valuable than mere true belief or opinion. This article looks at various formulations of the value problem and various accounts of the value of knowledge in ancient and modern philosophy. The article then considers some contemporary discussions of the value problem, including the charge that reliabilist accounts cannot account for the value of knowledge over mere true belief. Various virtue-theoretic accounts of epistemic value are discussed as possible improvements over process reliabilism, and the epistemic value of understanding (as compared to knowledge) is considered.

Metaphysics of composition

Composition occurs when one or more objects are parts of another object. The metaphysics of composition concerns the nature of composition – i.e. what it is, and how it works. Some of the more important questions philosophers have regarding the metaphysics of composition are the following: (1) When does composition occur? This is van Inwagen’s ‘Special Composition Question’. Four prominent answers to this question include: (i) objects compose another object when those former objects are in contact; (ii) any two or more objects compose another object; (iii) objects never compose another object; (iv) objects compose another object when the activities of the former objects constitute a life. (2) Are composite objects identical with their parts? Proponents of ‘composition as identity’ answer ‘yes’ to this question. There are two primary variants of composition as identity, ‘strong’ composition as identity and ‘weak’ composition as identity. The most prominent objection to strong composition as identity is an objection from Leibniz’s Law: composite objects cannot be identical with their parts, since they seem to have properties which their parts do not have. (3) Is it possible for one object to constitute another object? Here ‘constitution’ is the relation which is alleged to obtain between, for example, a clay statue and the lump of clay from which it is formed. We can distinguish between the thesis that constitution is identity, and the thesis that constitution is not identity. The chief motivation which leads some philosophers to reject the thesis that constitution is not identity is the ‘grounding problem’ for that thesis. (4) Are there, in addition to composite objects, the ‘forms’ of those objects, and if so, what is the relationship between composite objects and their forms? We can distinguish between (at least) two variants of hylomorphism (the thesis that objects have forms), with the main distinction between the two views being whether or not they regard forms as being among the parts of composite objects.

Feminist philosophy

Feminist philosophy is philosophy that is aimed at understanding and challenging the oppression of women. Feminist philosophy examines issues that are traditionally found in practical ethics and political philosophy, metaphysics, epistemology and philosophy of language. In fact, feminist concerns can appear in almost all areas of traditional philosophy. Feminist philosophy is thus not a kind of philosophy; rather, it is unified by its focus on issues of concern to feminists. Feminist philosophers question the structures and institutions that regulate our lives. When Mary Wollstonecraft was writing in 1792, the institutions excluded and subordinated women explicitly. Wollstonecraft, as the title of her book (A Vindication of the Rights of Woman) makes clear, was extending the enlightenment idea that men have basic human rights, to women. Wollstonecraft argued that women should not be seen as importantly different from men: there may be differences due to different upbringing, but, Wollstonecraft argues, there is no reason to think men and women differ in important ways, and women should be given the same education and opportunities as men. What seemed radical in 1792 may not seem radical now. Yet gender inequality persists. Thus philosophers must look beyond the formal rules and laws to the underlying structures that cause and perpetuate oppression. The feminist philosopher is always asking, ‘is there some element of this practice that depends on gender in some way?’ Feminist philosophers examine and critique the way we structure our families and reproduction, the cultural practices we engage in, such as prostitution and pornography, the way we think, and speak and value each other as knowers and thinkers. In order to examine these issues the feminist philosopher may need an improved conceptual toolbox: we need to understand such complex concepts as intersectionality, false consciousness, and of course, gender itself. Is gender biologically determined – is it something natural and immutable, or is it socially constructed? As Simone de Beauvoir puts it, ‘one is not born, but rather becomes, a woman’. Feminist philosophers tend to argue that gender is all (or mostly) socially constructed, that it is something we invent rather than discover. Gender is nonetheless an important part of our world, and feminist philosophy aims to understand how it works.

Searle, John (1932–)

John Rogers Searle (born July 31, 1932) is the Slusser Professor of Philosophy at the University of California, Berkeley. This analytic philosopher has made major contributions to the fields of the philosophy of mind, the philosophy of language, and social ontology. He is best known for his Chinese room argument, which aims to demonstrate that the formally described systems of computer functionalism cannot give rise to intentional understanding. Searle’s early work focused on the philosophy of language, where, in Speech Acts (1969), he explores the hypothesis that speaking a language is a rule-governed form of behavior. Just as one must follow certain rules in order to be considered to be playing chess, rules determine whether a speaker is making a promise, giving a command, asking a question, making a statement, and so forth. The kind of speech act that an utterance is depends on, among other conditions, its propositional content and illocutionary force. The content depicts the world as being a certain way, and the force specifies what a speaker is trying to do with that content. For example, for an utterance to qualify as a promise a speaker must describe a future act (content) and intend that the utterance place him or herself under an obligation to do that act (force). In Intentionality (1983), Searle argues that the structure of language not only mirrors but is derivative of the structure of intentional thought, so that core elements of his analysis of speech acts can be used as the basis for a theory of intentionality. Just as we can only promise by bringing certain propositional contents under a certain illocutionary force, intentional states such as belief, desire, fear, and joy can only be about the world in virtue of a representative content and a psychological mode. A theory of intentionality does not explain how intentionality is possible, given the basic facts of the world as identified by the natural sciences. Much of Searle’s work in the philosophy of mind, as found in Minds, Brains, and Science (1984) and The Rediscovery of the Mind (1992), is dedicated to the question of how mental facts, including but not limited to intentional facts, can be reconciled with basic, natural facts. Searle’s Chinese room argument is formulated in the service of rejecting computer functionalism, a prominent attempt at such reconciliation. Searle’s positive view, which he describes as "biological naturalism," is that mental facts are both caused by and features of underlying neurophysiological processes. In Speech Acts (1969), Searle claims that using language is akin to playing chess, in that both activities are made possible by participants following what he describes as "constitutive rules," rules that must be followed in order for someone to be considered to be undertaking those activities. Other institutional facts, such as money or the U.S. presidency, are also created and maintained in virtue of our following certain constitutive rules. For example, someone can only count as a U.S. president if that person is, among other conditions, a U.S. citizen who receives a majority of electoral votes. This thought is extended and explored in Searle’s two book-length contributions to the field of social ontology, The Construction of Social Reality (1995) and Making the Social World (2010). In addition to the philosophy of language and social ontology, Searle has made book-length contributions to the philosophy of action (Rationality in Action (2001)) and the philosophy of perception (Seeing Things as They Are: A Theory of Perception (2015)). He also famously engaged Jacques Derrida’s critique of J. L. Austin’s discussion of illocutionary acts ("Reiterating the Differences: A Reply to Derrida" (1977)). Searle has summarized his various positions in Mind, Language, and Society: Philosophy in the Real World (1998) and Mind: A Brief Introduction (2004).

Molyneux problem

The Molyneux problem asks whether a newly sighted person might immediately identify shapes previously known only to touch, like cubes and spheres, by sight alone. Over three centuries ago, the designer, William Molyneux, a Fellow of the Royal Society living in Ireland, conveyed the problem in a series of letters to John Locke. Locke soon published the problem and Molyneux’s own ‘not’ answer, in the second edition of his famous work, An Essay Concerning Human Understanding. Molyneux reasoned that the newly sighted person would fail for having no way to know that the newly seen shapes were like the felt shapes; the feel of the cube corner would not at all be like the look of the cube corner. Many philosophers have agreed with Molyneux’s ‘not’, arguing either that each sense produces concepts unique to it or that new sensory experiences, like those of newly sighted people, are too primitive for identifying three-dimensional shapes. Additionally, early experiments on subjects who have had cataracts surgically removed seem to confirm Molyneux’s supposition, as the newly sighted do not immediately identify shapes known to them by touch. More recent empirical experiments on cataract surgery subjects, newborns, and with technological innovations like sensory substitution devices, suggest support for a ‘yes’ answer to the question, inspiring philosophical and psychological accounts of perception that explain how the newly sighted might succeed in recognizing three-dimensional spatial features by sight.

Disjunctivism

The disjunctivist claims that the mental states involved in a case of successful – "veridical" – perception of an object differ from those involved in a hallucinatory experience of such an object, even in those cases in which the two experiences are indiscriminable for their subject. Among its supporters, there tend to be two main motivations for endorsing disjunctivism: because it is necessary if we are to hold that, in cases of successful perception, worldly objects and properties are literally constituents of our experiences, and because it offers us a way of responding to the challenge of skepticism. Among other things, its opponents argue that it is inconsistent with both empirical findings in, and the underlying commitments of, the psychology of vision, and challenge the disjunctivist to provide explanations of hallucination and illusion that explain how such states can be indiscriminable from veridical perceptions without positing some common factor – such as a common conscious / experiential core – that is shared by the different cases.

Ideals

Ideals are models of excellence. They can be moral or nonmoral, and either ‘substantive’ or ‘deliberative’. Substantive ideals present models of excellence against which things in a relevant class can be assessed, such as models of the just society or the good person. Deliberative ideals present models of excellent deliberation, leading to correct or warranted ethical conclusions. Ideals figure in ethics in two opposed ways. Most centrally, ideals serve to justify ethical judgments and to guide people in how to live. Sometimes, however, ideals may conflict with moral demands, thereby testing the limits of morality. Reliance upon ideals in the development of ethical theories seems unavoidable but raises difficult questions. How can the choice of a particular ideal be justified? How might conflicts between ideals and other values, especially moral demands, be resolved?