Phenomenology (philosophy)

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Phenomenology (from Greek phainómenon "that which appears" and lógos "study") is the philosophical study of the structures of experience and consciousness. As a philosophical movement it was founded in the early years of the 20th century by Edmund Husserl and was later expanded upon by a circle of his followers at the universities of Göttingen and Munich in Germany. It then spread to France, the United States, and elsewhere, often in contexts far removed from Husserl's early work.

 

Phenomenology is not a unitary movement; rather, different authors share a common family resemblance but also with many significant differences. Gabriella Farina states:

A unique and final definition of phenomenology is dangerous and perhaps even paradoxical as it lacks a thematic focus. In fact, it is not a doctrine, nor a philosophical school, but rather a style of thought, a method, an open and ever-renewed experience having different results, and this may disorient anyone wishing to define the meaning of phenomenology.

Phenomenology, in Husserl's conception, is primarily concerned with the systematic reflection on and study of the structures of consciousness and the phenomena that appear in acts of consciousness. Phenomenology can be clearly differentiated from the Cartesian method of analysis which sees the world as objects, sets of objects, and objects acting and reacting upon one another.

Husserl's conception of phenomenology has been criticized and developed not only by himself but also by students such as Edith Stein and Roman Ingarden, by hermeneutic philosophers such as Martin Heidegger, by existentialists such as Nicolai Hartmann, Gabriel Marcel, Maurice Merleau-Ponty, Jean-Paul Sartre, and by other philosophers such as Max Scheler, Paul Ricoeur, Jean-Luc Marion, Michel Henry, Emmanuel Levinas, Jacques Derrida, and sociologists Alfred Schütz and Eric Voegelin.

Overview

In its most basic form, phenomenology attempts to create conditions for the objective study of topics usually regarded as subjective: consciousness and the content of conscious experiences such as judgements, perceptions, and emotions. Although phenomenology seeks to be scientific, it does not attempt to study consciousness from the perspective of clinical psychology or neurology. Instead, it seeks through systematic reflection to determine the essential properties and structures of experience.

There are several assumptions behind phenomenology that help explain its foundations:

1. Phenomenologists reject the concept of objective research. They prefer grouping assumptions through a process called phenomenological epoché.
2. They believe that analyzing daily human behavior can provide one with a greater understanding of nature.
3. They assert that persons should be explored. This is because persons can be understood through the unique ways they reflect the society they live in.
4. Phenomenologists prefer to gather "capta", or conscious experience, rather than traditional data.
5. They consider phenomenology to be oriented toward discovery, and therefore they research using methods that are far less restrictive than in other sciences.

Husserl derived many important concepts central to phenomenology from the works and lectures of his teachers, the philosophers and psychologists Franz Brentano and Carl Stumpf. An important element of phenomenology that Husserl borrowed from Brentano is intentionality (often described as "aboutness"), the notion that consciousness is always consciousness of something. The object of consciousness is called the intentional object, and this object is constituted for consciousness in many different ways, through, for instance, perception, memory, retention and protention, signification, etc. Throughout these different intentionalities, though they have different structures and different ways of being "about" the object, an object is still constituted as the identical object; consciousness is directed at the same intentional object in direct perception as it is in the immediately following retention of this object and the eventual remembering of it. 

Though many of the phenomenological methods involve various reductions, phenomenology is, in essence, anti-reductionistic; the reductions are mere tools to better understand and describe the workings of consciousness, not to reduce any phenomenon to these descriptions. In other words, when a reference is made to a thing's essence or idea, or when the constitution of an identical coherent thing is specified by describing what one "really" sees as being only these sides and aspects, these surfaces, it does not mean that the thing is only and exclusively what is described here: the ultimate goal of these reductions is to understand how these different aspects are constituted into the actual thing as experienced by the person experiencing it. Phenomenology is a direct reaction to the psychologism and physicalism of Husserl's time.

Although previously employed by Georg Wilhelm Friedrich Hegel in his Phenomenology of Spirit, it was Husserl's adoption of this term (circa 1900) that propelled it into becoming the designation of a philosophical school. As a philosophical perspective, phenomenology is its method, though the specific meaning of the term varies according to how it is conceived by a given philosopher. As envisioned by Husserl, phenomenology is a method of philosophical inquiry that rejects the rationalist bias that has dominated Western thought since Plato in favor of a method of reflective attentiveness that discloses the individual's "lived experience." Loosely rooted in an epistemological device, with Sceptic roots, called epoché, Husserl's method entails the suspension of judgment while relying on the intuitive grasp of knowledge, free of presuppositions and intellectualizing. Sometimes depicted as the "science of experience," the phenomenological method is rooted in intentionality, i.e. Husserl's theory of consciousness (developed from Brentano). Intentionality represents an alternative to the representational theory of consciousness, which holds that reality cannot be grasped directly because it is available only through perceptions of reality that are representations of it in the mind. Husserl countered that consciousness is not "in" the mind; rather, consciousness is conscious of something other than itself (the intentional object), whether the object is a substance or a figment of imagination (i.e., the real processes associated with and underlying the figment). Hence the phenomenological method relies on the description of phenomena as they are given to consciousness, in their immediacy. 

According to Maurice Natanson (1973, p. 63), "The radicality of the phenomenological method is both continuous and discontinuous with philosophy's general effort to subject experience to fundamental, critical scrutiny: to take nothing for granted and to show the warranty for what we claim to know." In practice, it entails an unusual combination of discipline and detachment to bracket theoretical explanations and second-hand information while determining one's "naive" experience of the matter. (To "bracket" in this sense means to provisionally suspend or set aside some idea as a way to facilitate the inquiry by focusing only on its most significant components.) The phenomenological method serves to momentarily erase the world of speculation by returning the subject to his or her primordial experience of the matter, whether the object of inquiry is a feeling, an idea, or a perception. According to Husserl the suspension of belief in what we ordinarily take for granted or infer by conjecture diminishes the power of what we customarily embrace as objective reality. According to Rüdiger Safranski (1998, 72), "[Husserl's and his followers'] great ambition was to disregard anything that had until then been thought or said about consciousness or the world [while] on the lookout for a new way of letting the things [they investigated] approach them, without covering them up with what they already knew." 

Martin Heidegger modified Husserl's conception of phenomenology because of what Heidegger perceived as Husserl's subjectivist tendencies. Whereas Husserl conceived humans as having been constituted by states of consciousness, Heidegger countered that consciousness is peripheral to the primacy of one's existence (i.e., the mode of being of Dasein), which cannot be reduced to one's consciousness of it. From this angle, one's state of mind is an "effect" rather than a determinant of existence, including those aspects of existence of which one is not conscious. By shifting the center of gravity from consciousness (psychology) to existence (ontology), Heidegger altered the subsequent direction of phenomenology. As one consequence of Heidegger's modification of Husserl's conception, phenomenology became increasingly relevant to psychoanalysis. Whereas Husserl gave priority to a depiction of consciousness that was fundamentally alien to the psychoanalytic conception of the unconscious, Heidegger offered a way to conceptualize experience that could accommodate those aspects of one's existence that lie on the periphery of sentient awareness.

Historical overview of the use of the term

Phenomenology has at least three main meanings in philosophical history: one in the writings of G. W. F. Hegel, another in the writings of Edmund Husserl in 1920, and thirdly, succeeding Husserl's work, in the writings of his former research assistant Martin Heidegger in 1927.

• For G. W. F. Hegel, phenomenology is an approach to philosophy that begins with an exploration of phenomena (what presents itself to us in conscious experience) as a means to finally grasp the absolute, logical, ontological and metaphysical Spirit that is behind phenomena. This has been called dialectical phenomenology.
• For Edmund Husserl, phenomenology is "the reflective study of the essence of consciousness as experienced from the first-person point of view." Phenomenology takes the intuitive experience of phenomena (whatever presents itself in phenomenological reflexion) as its starting point and tries to extract from it the essential features of experiences and the essence of what we experience. When generalized to the essential features of any possible experience, this has been called transcendental phenomenology. Husserl's view was based on aspects of the work of Franz Brentano and was developed further by philosophers such as Maurice Merleau-Ponty, Max Scheler, Edith Stein, Dietrich von Hildebrand and Emmanuel Levinas.

Although the term "phenomenology" was used occasionally in the history of philosophy before Husserl, modern use ties it more explicitly to his particular method. Following is a list of important thinkers, in rough chronological order, who used the term "phenomenology" in a variety of ways, with brief comments on their contributions:

• Friedrich Christoph Oetinger (1702–1782), German pietist, for the study of the "divine system of relations"
• Johann Heinrich Lambert (1728–1777), mathematician, physician and philosopher, known for the theory of appearances underlying empirical knowledge.
• Immanuel Kant (1724–1804), in the Critique of Pure Reason, distinguished between objects as phenomena, which are objects as shaped and grasped by human sensibility and understanding, and objects as things-in-themselves or noumena, which do not appear to us in space and time and about which we can make no legitimate judgments.
• G. W. F. Hegel (1770–1831) challenged Kant's doctrine of the unknowable thing-in-itself, and declared that by knowing phenomena more fully we can gradually arrive at a consciousness of the absolute and spiritual truth of Divinity, most notably in his Phenomenology of Spirit, published in 1807.
• Carl Stumpf (1848–1936), student of Brentano and mentor to Husserl, used "phenomenology" to refer to an ontology of sensory contents.
• Edmund Husserl (1859–1938) established phenomenology at first as a kind of "descriptive psychology" and later as a transcendental and eidetic science of consciousness. He is considered to be the founder of contemporary phenomenology.
• Max Scheler (1874–1928) developed further the phenomenological method of Edmund Husserl and extended it to include also a reduction of the scientific method. He influenced the thinking of Pope John Paul II, Dietrich von Hildebrand, and Edith Stein.
• Martin Heidegger (1889–1976) criticized Husserl's theory of phenomenology and attempted to develop a theory of ontology that led him to his original theory of Dasein, the non-dualistic human being.
• Alfred Schütz (1899–1959) developed a phenomenology of the social world on the basis of everyday experience that has influenced major sociologists such as Harold Garfinkel, Peter Berger, and Thomas Luckmann.
• Francisco Varela (1946–2001), Chilean philosopher and biologist. Developed the basis for experimental phenomenology and neurophenomenology.

Later usage is mostly based on or (critically) related to Husserl's introduction and use of the term. This branch of philosophy differs from others in that it tends to be more "descriptive" than "prescriptive".

Varieties of phenomenology

The Encyclopedia of Phenomenology (Kluwer Academic Publishers, 1997) features separate articles on the following seven types of phenomenology:

1. Transcendental constitutive phenomenology studies how objects are constituted in transcendental consciousness, setting aside questions of any relation to the natural world.
2. Naturalistic constitutive phenomenology studies how consciousness constitutes things in the world of nature, assuming with the natural attitude that consciousness is part of nature.
3. Existential phenomenology studies concrete human existence, including our experience of free choice and/or action in concrete situations.
4. Generative historicist phenomenology studies how meaning—as found in our experience—is generated in historical processes of collective experience over time.
5. Genetic phenomenology studies the emergence/genesis of meanings of things within one's own stream of experience.
6. Hermeneutical phenomenology (also hermeneutic phenomenology or post-phenomenology/postphenomenology) studies interpretive structures of experience.
7. Realistic phenomenology (also realist phenomenology elsewhere) studies the structure of consciousness and intentionality as "it occurs in a real world that is largely external to consciousness and not somehow brought into being by consciousness."

The contrast between "constitutive phenomenology" (German: konstitutive Phänomenologie; also static phenomenology (statische Phänomenologie) or descriptive phenomenology (beschreibende Phänomenologie)) and "genetic phenomenology" (genetische Phänomenologie; also phenomenology of genesis (Phänomenologie der Genesis)) is due to Husserl.

Modern scholarship also recognizes the existence of the following varieties: late Heidegger's transcendental hermeneutic phenomenology, Maurice Merleau-Ponty's embodied phenomenology, Michel Henry's material phenomenology (also based on embodied cognition), analytic phenomenology, J. L. Austin's linguistic phenomenology, and post-analytic phenomenology.

Phenomenological terminology

Intentionality

Main article: Intentionality

Intentionality refers to the notion that consciousness is always the consciousness of something. The word itself should not be confused with the "ordinary" use of the word intentional, but should rather be taken as playing on the etymological roots of the word. Originally, intention referred to a "stretching out" ("in tension," from Latin intendere), and in this context it refers to consciousness "stretching out" towards its object. However, one should be careful with this image: there is not some consciousness first that, subsequently, stretches out to its object; rather, consciousness occurs as the simultaneity of a conscious act and its object. 

Intentionality is often summed up as "aboutness." Whether this something that consciousness is about is in direct perception or in fantasy is inconsequential to the concept of intentionality itself; whatever consciousness is directed at, that is what consciousness is conscious of. This means that the object of consciousness doesn't have to be a physical object apprehended in perception: it can just as well be a fantasy or a memory. Consequently, these "structures" of consciousness, i.e., perception, memory, fantasy, etc., are called intentionalities. 

The term "intentionality" originated with the Scholastics in the medieval period and was resurrected by Brentano who in turn influenced Husserl's conception of phenomenology, who refined the term and made it the cornerstone of his theory of consciousness. The meaning of the term is complex and depends entirely on how it is conceived by a given philosopher. The term should not be confused with "intention" or the psychoanalytic conception of unconscious "motive" or "gain".

Intuition

Intuition in phenomenology refers to cases where the intentional object is directly present to the intentionality at play; if the intention is "filled" by the direct apprehension of the object, you have an intuited object. Having a cup of coffee in front of you, for instance, seeing it, feeling it, or even imagining it – these are all filled intentions, and the object is then intuited. The same goes for the apprehension of mathematical formulae or a number. If you do not have the object as referred to directly, the object is not intuited, but still intended, but then emptily. Examples of empty intentions can be signitive intentions – intentions that only imply or refer to their objects.

Evidence

In everyday language, we use the word evidence to signify a special sort of relation between a state of affairs and a proposition: State A is evidence for the proposition "A is true." In phenomenology, however, the concept of evidence is meant to signify the "subjective achievement of truth." This is not an attempt to reduce the objective sort of evidence to subjective "opinion," but rather an attempt to describe the structure of having something present in intuition with the addition of having it present as intelligible: "Evidence is the successful presentation of an intelligible object, the successful presentation of something whose truth becomes manifest in the evidencing itself."

Noesis and noema

In Husserl's phenomenology, which is quite common, this pair of terms, derived from the Greek nous (mind), designate respectively the real content, noesis, and the ideal content, noema, of an intentional act (an act of consciousness). The Noesis is the part of the act that gives it a particular sense or character (as in judging or perceiving something, loving or hating it, accepting or rejecting it, and so on). This is real in the sense that it is actually part of what takes place in the consciousness (or psyche) of the subject of the act. The Noesis is always correlated with a Noema; for Husserl, the full Noema is a complex ideal structure comprising at least a noematic sense and a noematic core. The correct interpretation of what Husserl meant by the Noema has long been controversial, but the noematic sense is generally understood as the ideal meaning of the act and the noematic core as the act's referent or object as it is meant in the act. One element of controversy is whether this noematic object is the same as the actual object of the act (assuming it exists) or is some kind of ideal object.

Empathy and intersubjectivity

In phenomenology, empathy refers to the experience of one's own body as another. While we often identify others with their physical bodies, this type of phenomenology requires that we focus on the subjectivity of the other, as well as our intersubjective engagement with them. In Husserl's original account, this was done by a sort of apperception built on the experiences of your own lived-body. The lived body is your own body as experienced by yourself, as yourself. Your own body manifests itself to you mainly as your possibilities of acting in the world. It is what lets you reach out and grab something, for instance, but it also, and more importantly, allows for the possibility of changing your point of view. This helps you differentiate one thing from another by the experience of moving around it, seeing new aspects of it (often referred to as making the absent present and the present absent), and still retaining the notion that this is the same thing that you saw other aspects of just a moment ago (it is identical). Your body is also experienced as a duality, both as object (you can touch your own hand) and as your own subjectivity (you experience being touched).

The experience of your own body as your own subjectivity is then applied to the experience of another's body, which, through apperception, is constituted as another subjectivity. You can thus recognise the Other's intentions, emotions, etc. This experience of empathy is important in the phenomenological account of intersubjectivity. In phenomenology, intersubjectivity constitutes objectivity (i.e., what you experience as objective is experienced as being intersubjectively available – available to all other subjects. This does not imply that objectivity is reduced to subjectivity nor does it imply a relativist position, cf. for instance intersubjective verifiability).

In the experience of intersubjectivity, one also experiences oneself as being a subject among other subjects, and one experiences oneself as existing objectively for these Others; one experiences oneself as the noema of Others' noeses, or as a subject in another's empathic experience. As such, one experiences oneself as objectively existing subjectivity. Intersubjectivity is also a part in the constitution of one's lifeworld, especially as "homeworld."

Lifeworld

The lifeworld (German: Lebenswelt) is the "world" each one of us lives in. One could call it the "background" or "horizon" of all experience, and it is that on which each object stands out as itself (as different) and with the meaning it can only hold for us. The lifeworld is both personal and intersubjective (it is then called a "homeworld"), and, as such, it does not enclose each one of us in a solus ipse.

Husserl's Logische Untersuchungen (1900/1901)

In the first edition of the Logical Investigations, still under the influence of Brentano, Husserl describes his position as "descriptive psychology." Husserl analyzes the intentional structures of mental acts and how they are directed at both real and ideal objects. The first volume of the Logical Investigations, the Prolegomena to Pure Logic, begins with a devastating critique of psychologism, i.e., the attempt to subsume the a priori validity of the laws of logic under psychology. Husserl establishes a separate field for research in logic, philosophy, and phenomenology, independently from the empirical sciences.

Transcendental phenomenology after the Ideen (1913)

Some years after the publication of the Logical Investigations, Husserl made some key elaborations that led him to the distinction between the act of consciousness (noesis) and the phenomena at which it is directed (the noemata).

• "noetic" refers to the intentional act of consciousness (believing, willing, etc.)
• "noematic" refers to the object or content (noema), which appears in the noetic acts (the believed, wanted, hated, and loved ...).

What we observe is not the object as it is in itself, but how and inasmuch it is given in the intentional acts. Knowledge of essences would only be possible by "bracketing" all assumptions about the existence of an external world and the inessential (subjective) aspects of how the object is concretely given to us. This procedure Husserl called epoché. 

Husserl in a later period concentrated more on the ideal, essential structures of consciousness. As he wanted to exclude any hypothesis on the existence of external objects, he introduced the method of phenomenological reduction to eliminate them. What was left over was the pure transcendental ego, as opposed to the concrete empirical ego. Now Transcendental Phenomenology is the study of the essential structures that are left in pure consciousness: This amounts in practice to the study of the noemata and the relations among them. The philosopher Theodor Adorno criticised Husserl's concept of phenomenological epistemology in his metacritique Against Epistemology, which is anti-foundationalist in its stance. 

Transcendental phenomenologists include Oskar Becker, Aron Gurwitsch, and Alfred Schütz.

Realist phenomenology

After Husserl's publication of the Ideen in 1913, many phenomenologists took a critical stance towards his new theories. Especially the members of the Munich group distanced themselves from his new transcendental phenomenology and preferred the earlier realist phenomenology of the first edition of the Logical Investigations. 

Realist phenomenologists include Adolf Reinach, Alexander Pfänder, Johannes Daubert [de], Max Scheler, Roman Ingarden, Nicolai Hartmann, Dietrich von Hildebrand.

Existential phenomenology

Existential phenomenology differs from transcendental phenomenology by its rejection of the transcendental ego. Merleau-Ponty objects to the ego's transcendence of the world, which for Husserl leaves the world spread out and completely transparent before the conscious. Heidegger thinks of a conscious being as always already in the world. Transcendence is maintained in existential phenomenology to the extent that the method of phenomenology must take a presuppositionless starting point – transcending claims about the world arising from, for example, natural or scientific attitudes or theories of the ontological nature of the world.

While Husserl thought of philosophy as a scientific discipline that had to be founded on a phenomenology understood as epistemology, Martin Heidegger held a radically different view. Heidegger himself states their differences this way:

For Husserl, the phenomenological reduction is the method of leading phenomenological vision from the natural attitude of the human being whose life is involved in the world of things and persons back to the transcendental life of consciousness and its noetic-noematic experiences, in which objects are constituted as correlates of consciousness. For us, phenomenological reduction means leading phenomenological vision back from the apprehension of a being, whatever may be the character of that apprehension, to the understanding of the Being of this being (projecting upon the way it is unconcealed).

According to Heidegger, philosophy was not at all a scientific discipline, but more fundamental than science itself. According to him science is only one way of knowing the world with no special access to truth. Furthermore, the scientific mindset itself is built on a much more "primordial" foundation of practical, everyday knowledge. Husserl was skeptical of this approach, which he regarded as quasi-mystical, and it contributed to the divergence in their thinking.

Instead of taking phenomenology as prima philosophia or a foundational discipline, Heidegger took it as a metaphysical ontology: "being is the proper and sole theme of philosophy... this means that philosophy is not a science of beings but of being." Yet to confuse phenomenology and ontology is an obvious error. Phenomena are not the foundation or Ground of Being. Neither are they appearances, for, as Heidegger argues in Being and Time, an appearance is "that which shows itself in something else," while a phenomenon is "that which shows itself in itself."

While for Husserl, in the epoché, being appeared only as a correlate of consciousness, for Heidegger being is the starting point. While for Husserl we would have to abstract from all concrete determinations of our empirical ego, to be able to turn to the field of pure consciousness, Heidegger claims that "the possibilities and destinies of philosophy are bound up with man's existence, and thus with temporality and with historicality."

However, ontological being and existential being are different categories, so Heidegger's conflation of these categories is, according to Husserl's view, the root of Heidegger's error. Husserl charged Heidegger with raising the question of ontology but failing to answer it, instead switching the topic to the Dasein, the only being for whom Being is an issue. That is neither ontology nor phenomenology, according to Husserl, but merely abstract anthropology. To clarify, perhaps, by abstract anthropology, as a non-existentialist searching for essences, Husserl rejected the existentialism implicit in Heidegger's distinction between beings qua existents as things in reality and their Being as it unfolds in Dasein's own reflections on its being-in-the-world, wherein being becomes present to us, that is, is unconcealed.

Existential phenomenologists include: Martin Heidegger (1889–1976), Hannah Arendt (1906–1975), Karl Jaspers (1883–1969), Emmanuel Levinas (1906–1995), Gabriel Marcel (1889–1973), Jean-Paul Sartre (1905–1980), Paul Ricoeur (1913–2005) and Maurice Merleau-Ponty (1908–1961).

Eastern thought

Some researchers in phenomenology (in particular in reference to Heidegger's legacy) see possibilities of establishing dialogues with traditions of thought outside of the so-called Western philosophy, particularly with respect to East-Asian thinking, and despite perceived differences between "Eastern" and "Western". Furthermore, it has been claimed that a number of elements within phenomenology (mainly Heidegger's thought) have some resonance with Eastern philosophical ideas, particularly with Zen Buddhism and Taoism. According to Tomonobu Imamichi, the concept of Dasein was inspired – although Heidegger remained silent on this – by Okakura Kakuzo's concept of das-in-der-Welt-sein (being in the world) expressed in The Book of Tea to describe Zhuangzi's philosophy, which Imamichi's teacher had offered to Heidegger in 1919, after having studied with him the year before.

There are also recent signs of the reception of phenomenology (and Heidegger's thought in particular) within scholarly circles focused on studying the impetus of metaphysics in the history of ideas in Islam and Early Islamic philosophy such as in the works of the Lebanese philosopher Nader El-Bizri; perhaps this is tangentially due to the indirect influence of the tradition of the French Orientalist and phenomenologist Henri Corbin, and later accentuated through El-Bizri's dialogues with the Polish phenomenologist Anna-Teresa Tymieniecka.

In addition, the work of Jim Ruddy in the field of comparative philosophy, combined the concept of Transcendental Ego in Husserl's phenomenology with the concept of the primacy of self-consciousness in the work of Sankaracharya. In the course of this work, Ruddy uncovered a wholly new eidetic phenomenological science, which he called "convergent phenomenology." This new phenomenology takes over where Husserl left off, and deals with the constitution of relation-like, rather than merely thing-like, or "intentional" objectivity.

Technoethics

Phenomenological approach to technology

James Moor has argued that computers show us policy vacuums that require new thinking and the establishment of new policies. Others have argued that the resources provided by classical ethical theory such as utilitarianism, consequentialism and deontological ethics is more than enough to deal with all the ethical issues emerging from our design and use of information technology.

For the phenomenologist the 'impact view' of technology as well as the constructivist view of the technology/society relationships is valid but not adequate (Heidegger 1977, Borgmann 1985, Winograd and Flores 1987, Ihde 1990, Dreyfus 1992, 2001). They argue that these accounts of technology, and the technology/society relationship, posit technology and society as if speaking about the one does not immediately and already draw upon the other for its ongoing sense or meaning. For the phenomenologist, society and technology co-constitute each other; they are each other's ongoing condition, or possibility for being what they are. For them technology is not just the artifact. Rather, the artifact already emerges from a prior 'technological' attitude towards the world (Heidegger 1977).

Heidegger's approach (pre-technological age)

For Heidegger the essence of technology is the way of being of modern humans—a way of conducting themselves towards the world—that sees the world as something to be ordered and shaped in line with projects, intentions and desires—a 'will to power' that manifests itself as a 'will to technology'. Heidegger claims that there were other times in human history, a pre-modern time, where humans did not orient themselves towards the world in a technological way—simply as resources for our purposes.

However, according to Heidegger this 'pre-technological' age (or mood) is one where humans' relation with the world and artifacts, their way of being disposed, was poetic and aesthetic rather than technological (enframing). There are many who disagree with Heidegger's account of the modern technological attitude as the 'enframing' of the world. For example, Andrew Feenberg argues that Heidegger's account of modern technology is not borne out in contemporary everyday encounters with technology. Christian Fuchs has written on the anti-Semitism rooted in Heidegger's view of technology.

The Hubert Dreyfus approach (contemporary society)

In critiquing the artificial intelligence (AI) programme, Hubert Dreyfus (1992) argues that the way skill development has become understood in the past has been wrong. He argues, this is the model that the early artificial intelligence community uncritically adopted. In opposition to this view, he argues, with Heidegger, that what we observe when we learn a new skill in everyday practice is in fact the opposite. We most often start with explicit rules or preformulated approaches and then move to a multiplicity of particular cases, as we become an expert. His argument draws directly on Heidegger's account in "Being and Time" of humans as beings that are always already situated in-the-world. As humans 'in-the-world', we are already experts at going about everyday life, at dealing with the subtleties of every particular situation; that is why everyday life seems so obvious. Thus, the intricate expertise of everyday activity is forgotten and taken for granted by AI as an assumed starting point. What Dreyfus highlighted in his critique of AI was the fact that technology (AI algorithms) does not make sense by itself. It is the assumed, and forgotten, horizon of everyday practice that makes technological devices and solutions show up as meaningful. If we are to understand technology we need to 'return' to the horizon of meaning that made it show up as the artifacts we need, want and desire. We need to consider how these technologies reveal (or disclose) us.

Intentional stance

From Wikipedia, the free encyclopedia

 

The intentional stance is a term coined by philosopher Daniel Dennett for the level of abstraction in which we view the behavior of an entity in terms of mental properties. It is part of a theory of mental content proposed by Dennett, which provides the underpinnings of his later works on free will, consciousness, folk psychology, and evolution.

Here is how it works: first you decide to treat the object whose behavior is to be predicted as a rational agent; then you figure out what beliefs that agent ought to have, given its place in the world and its purpose. Then you figure out what desires it ought to have, on the same considerations, and finally you predict that this rational agent will act to further its goals in the light of its beliefs. A little practical reasoning from the chosen set of beliefs and desires will in most instances yield a decision about what the agent ought to do; that is what you predict the agent will do.

— Daniel Dennett, The Intentional Stance, p. 17

Dennett and intentionality

Dennett (1971, p. 87) states that he took the concept of "intentionality" from the work of the German philosopher Franz Brentano. When clarifying the distinction between mental phenomena (viz., mental activity) and physical phenomena, Brentano (p. 97) argued that, in contrast with physical phenomena, the "distinguishing characteristic of all mental phenomena" was "the reference to something as an object" – a characteristic he called "intentional inexistence". Dennett constantly speaks of the "aboutness" of intentionality; for example: "the aboutness of the pencil marks composing a shopping list is derived from the intentions of the person whose list it is" (Dennett, 1995, p. 240). 

John Searle (1999, pp. 85) stresses that "competence" in predicting/explaining human behaviour involves being able to both recognize others as "intentional" beings, and interpret others' minds as having "intentional states" (e.g., beliefs and desires):

The primary evolutionary role of the mind is to relate us in certain ways to the environment, and especially to other people. My subjective states relate me to the rest of the world, and the general name of that relationship is "intentionality." These subjective states include beliefs and desires, intentions and perceptions, as well as loves and hates, fears and hopes. "Intentionality," to repeat, is the general term for all the various forms by which the mind can be directed at, or be about, or of, objects and states of affairs in the world. (p.85)

According to Dennett (1987, pp. 48–49), folk psychology provides a systematic, "reason-giving explanation" for a particular action, and an account of the historical origins of that action, based on deeply embedded assumptions about the agent; namely that:

• the agent's action was entirely rational;
• the agent's action was entirely reasonable (in the prevailing circumstances);
• the agent held certain beliefs;
• the agent desired certain things; and
• the agent's future action could be systematically predicted from the beliefs and desires so ascribed.

This approach is also consistent with the earlier work of Fritz Heider and Marianne Simmel, whose joint study revealed that, when subjects were presented with an animated display of 2-dimensional shapes, they were inclined to ascribe intentions to the shapes.

Further, Dennett (1987, p. 52) argues that, based on our fixed personal views of what all humans ought to believe, desire and do, we predict (or explain) the beliefs, desires and actions of others "by calculating in a normative system"; and, driven by the reasonable assumption that all humans are rational beings – who do have specific beliefs and desires and do act on the basis of those beliefs and desires in order to get what they want – these predictions/explanations are based on four simple rules:

1. The agent's beliefs are those a rational individual ought to have (i.e., given their "perceptual capacities", "epistemic needs" and "biography");
2. In general, these beliefs "are both true and relevant to [their] life;
3. The agent's desires are those a rational individual ought to have (i.e., given their "biological needs", and "the most practicable means of satisfying them") in order to further their "survival" and "procreation" needs; and
4. The agent's behaviour will be composed of those acts a rational individual holding those beliefs (and having those desires) ought to perform.

Dennett's three levels

The core idea is that, when understanding, explaining, and/or predicting the behavior of an object, we can choose to view it at varying levels of abstraction. The more concrete the level, the more accurate in principle our predictions are; the more abstract, the greater the computational power we gain by zooming out and skipping over the irrelevant details.

Dennett defines three levels of abstraction, attained by adopting one of three entirely different "stances", or intellectual strategies: the physical stance; the design stance; and the intentional stance:

• The most concrete is the physical stance, the domain of physics and chemistry, which makes predictions from knowledge of the physical constitution of the system and the physical laws that govern its operation; and thus, given a particular set of physical laws and initial conditions, and a particular configuration, a specific future state is predicted (this could also be called the "structure stance"). At this level, we are concerned with such things as mass, energy, velocity, and chemical composition. When we predict where a ball is going to land based on its current trajectory, we are taking the physical stance. Another example of this stance comes when we look at a strip made up of two types of metal bonded together and predict how it will bend as the temperature changes, based on the physical properties of the two metals.
• Somewhat more abstract is the design stance, the domain of biology and engineering, which requires no knowledge of the physical constitution or the physical laws that govern a system's operation. Based on an implicit assumption that there is no malfunction in the system, predictions are made from knowledge of the purpose of the system's design (this could also be called the "teleological stance"). At this level, we are concerned with such things as purpose, function and design. When we predict that a bird will fly when it flaps its wings on the basis that wings are made for flying, we are taking the design stance. Likewise, we can understand the bimetallic strip as a particular type of thermometer, not concerning ourselves with the details of how this type of thermometer happens to work. We can also recognize the purpose that this thermometer serves inside a thermostat and even generalize to other kinds of thermostats that might use a different sort of thermometer. We can even explain the thermostat in terms of what it's good for, saying that it keeps track of the temperature and turns on the heater whenever it gets below a minimum, turning it off once it reaches a maximum.
• Most abstract is the intentional stance, the domain of software and minds, which requires no knowledge of either structure or design, and "[clarifies] the logic of mentalistic explanations of behaviour, their predictive power, and their relation to other forms of explanation" (Bolton & Hill, 1996, p. 24). Predictions are made on the basis of explanations expressed in terms of meaningful mental states; and, given the task of predicting or explaining the behaviour of a specific agent (a person, animal, corporation, artifact, nation, etc.), it is implicitly assumed that the agent will always act on the basis of its beliefs and desires in order to get precisely what it wants (this could also be called the "folk psychology stance"). At this level, we are concerned with such things as belief, thinking and intent. When we predict that the bird will fly away because it knows the cat is coming and is afraid of getting eaten, we are taking the intentional stance. Another example would be when we predict that Mary will leave the theater and drive to the restaurant because she sees that the movie is over and is hungry.
• In 1971, Dennett also postulated that, whilst "the intentional stance presupposes neither lower stance", there may well be a fourth, higher level: a "truly moral stance toward the system" – the "personal stance" – which not only "presupposes the intentional stance" (viz., treats the system as rational) but also "views it as a person" (1971/1978, p. 240).

A key point is that switching to a higher level of abstraction has its risks as well as its benefits. For example, when we view both a bimetallic strip and a tube of mercury as thermometers, we can lose track of the fact that they differ in accuracy and temperature range, leading to false predictions as soon as the thermometer is used outside the circumstances for which it was designed. The actions of a mercury thermometer heated to 500 °C can no longer be predicted on the basis of treating it as a thermometer; we have to sink down to the physical stance to understand it as a melted and boiled piece of junk. For that matter, the "actions" of a dead bird are not predictable in terms of beliefs or desires. 

Even when there is no immediate error, a higher-level stance can simply fail to be useful. If we were to try to understand the thermostat at the level of the intentional stance, ascribing to it beliefs about how hot it is and a desire to keep the temperature just right, we would gain no traction over the problem as compared to staying at the design stance, but we would generate theoretical commitments that expose us to absurdities, such as the possibility of the thermostat not being in the mood to work today because the weather is so nice. Whether to take a particular stance, then, is determined by how successful that stance is when applied. 

Dennett argues that it is best to understand human behavior at the level of the intentional stance, without making any specific commitments to any deeper reality of the artifacts of folk psychology. In addition to the controversy inherent in this, there is also some dispute about the extent to which Dennett is committing to realism about mental properties. Initially, Dennett's interpretation was seen as leaning more towards instrumentalism, but over the years, as this idea has been used to support more extensive theories of consciousness, it has been taken as being more like Realism. His own words hint at something in the middle, as he suggests that the self is as real as a center of gravity, "an abstract object, a theorist's fiction", but operationally valid.

As a way of thinking about things, Dennett's intentional stance is entirely consistent with everyday commonsense understanding; and, thus, it meets Eleanor Rosch's (1978, p. 28) criterion of the "maximum information with the least cognitive effort". Rosch argues that, implicit within any system of categorization, are the assumptions that:

• the major purpose of any system of categorization is to reduce the randomness of the universe by providing "maximum information with the least cognitive effort", and
• the real world is structured and systematic, rather than being arbitrary or unpredictable. Thus, if a particular way of categorizing information does, indeed, "provide maximum information with the least cognitive effort", it can only do so because the structure of that particular system of categories corresponds with the perceived structure of the real world.

Also, the intentional stance meets the criteria Dennett specified (1995, pp. 50–51) for algorithms:

• Substrate Neutrality: It is a "mechanism" that produces results regardless of the material used to perform the procedure ("the power of the procedure is due to its logical structure, not the causal powers of the materials used in the instantiation").
• Underlying Mindlessness: Each constituent step, and each transition between each step, is so utterly simple, that they can be performed by a "dutiful idiot".
• Guaranteed Results: "Whatever it is that an algorithm does, it always does it, if it is executed without misstep. An algorithm is a foolproof recipe."

Variants of Dennett's three stances

The general notion of a three level system was widespread in the late 1970s/early 1980s; for example, when discussing the mental representation of information from a cognitive psychology perspective, Glass and his colleagues (1979, p. 24) distinguished three important aspects of representation:

1. the content ("what is being represented");
2. the code ("the format of the representation"); and
3. the medium ("the physical realization of the code").

Other significant cognitive scientists who also advocated a three level system were Allen Newell, Zenon Pylyshyn, and David Marr. The parallels between the four representations (each of which implicitly assumed that computers and human minds displayed each of the three distinct levels) are detailed in the following table: 

Daniel Dennett "Stances"	Zenon Pylyshyn "Levels of Organization"	Allen Newell "Levels of Description"	David Marr "Levels of Analysis"
Physical Stance.	Physical Level, or Biological Level.	Physical Level, or Device Level.	Hardware Implementation Level.
Design Stance.	Symbol Level.	Program Level, or Symbol Level.	Representation and Algorithm Level.
Intentional Stance.	Semantic, or Knowledge Level.	Knowledge Level.	Computational Theory Level.

Objections and replies

The most obvious objection to Dennett is the intuition that it "matters" to us whether an object has an inner life or not. The claim is that we don't just imagine the intentional states of other people in order to predict their behaviour; the fact that they have thoughts and feelings just like we do is central to notions such as trust, friendship and love. The Blockhead argument proposes that someone, Jones, has a twin who is in fact not a person but a very sophisticated robot which looks and acts like Jones in every way, but who (it is claimed) somehow does not have any thoughts or feelings at all, just a chip which controls his behaviour; in other words, "the lights are on but no one's home". According to the intentional systems theory (IST), Jones and the robot have precisely the same beliefs and desires, but this is claimed to be false. The IST expert assigns the same mental states to Blockhead as he does to Jones, "whereas in fact [Blockhead] has not a thought in his head." Dennett has argued against this by denying the premise, on the basis that the robot is a philosophical zombie and therefore metaphysically impossible. In other words, if something acts in all ways conscious, it necessarily is, as consciousness is defined in terms of behavioral capacity, not ineffable qualia.

Another objection attacks the premise that treating people as ideally rational creatures will yield the best predictions. Stephen Stich argues that people often have beliefs or desires which are irrational or bizarre, and IST doesn't allow us to say anything about these. If the person's "environmental niche" is examined closely enough, and the possibility of malfunction in their brain (which might affect their reasoning capacities) is looked into, it may be possible to formulate a predictive strategy specific to that person. Indeed this is what we often do when someone is behaving unpredictably — we look for the reasons why. In other words, we can only deal with irrationality by contrasting it against the background assumption of rationality. This development significantly undermines the claims of the intentional stance argument. 

The rationale behind the intentional stance is based on evolutionary theory, particularly the notion that the ability to make quick predictions of a system's behaviour based on what we think it might be thinking was an evolutionary adaptive advantage. The fact that our predictive powers are not perfect is a further result of the advantages sometimes accrued by acting contrary to expectations.

Neural evidence

Philip Robbins and Anthony I. Jack suggest that "Dennett's philosophical distinction between the physical and intentional stances has a lot going for it" from the perspective of psychology and neuroscience. They review studies on abilities to adopt an intentional stance (variously called "mindreading," "mentalizing," or "theory of mind") as distinct from adopting a physical stance ("folk physics," "intuitive physics," or "theory of body"). Autism seems to be a deficit in the intentional stance with preservation of the physical stance, while Williams syndrome can involve deficits in the physical stance with preservation of the intentional stance. This tentatively suggests a double dissociation of intentional and physical stances in the brain. However, most studies have found no evidence of impairment in autistic individuals' ability to understand other people's basic intentions or goals; instead, data suggests that impairments are found in understanding more complex social emotions or in considering others' viewpoints.

Robbins and Jack point to a 2003 study in which participants viewed animated geometric shapes in different "vignettes," some of which could be interpreted as constituting social interaction, while others suggested mechanical behavior. Viewing social interactions elicited activity in brain regions associated with identifying faces and biological objects (posterior temporal cortex), as well as emotion processing (right amygdala and ventromedial prefrontal cortex). Meanwhile, the mechanical interactions activated regions related to identifying objects like tools that can be manipulated (posterior temporal lobe). The authors suggest "that these findings reveal putative 'core systems' for social and mechanical understanding that are divisible into constituent parts or elements with distinct processing and storage capabilities."

Phenomenal stance

Robbins and Jack argue for an additional stance beyond the three that Dennett outlined. They call it the phenomenal stance: Attributing consciousness, emotions, and inner experience to a mind. The explanatory gap of the hard problem of consciousness illustrates this tendency of people to see phenomenal experience as different from physical processes. The authors suggest that psychopathy may represent a deficit in the phenomenal but not intentional stance, while people with autism appear to have intact moral sensibilities, just not mind-reading abilities. These examples suggest a double dissociation between the intentional and phenomenal stances.

In a follow-up paper, Robbins and Jack describe four experiments about how the intentional and phenomenal stances relate to feelings of moral concern. The first two experiments showed that talking about lobsters as strongly emotional led to a much greater sentiment that lobsters deserved welfare protections than did talking about lobsters as highly intelligent. The third and fourth studies found that perceiving an agent as vulnerable led to greater attributions of phenomenal experience. Also, people who scored higher on the empathetic-concern subscale of the Interpersonal Reactivity Index had generally higher absolute attributions of mental experience.

Bryce Huebner (2010) performed two experimental philosophy studies to test students' ascriptions of various mental states to humans compared with cyborgs and robots. Experiment 1 showed that while students attributed both beliefs and pains most strongly to humans, they were more willing to attribute beliefs than pains to robots and cyborgs. "[T]hese data seem to confirm that commonsense psychology does draw a distinction between phenomenal and non-phenomenal states--and this distinction seems to be dependent on the structural properties of an entity in a way that ascriptions of non-phenomenal states are not." However, this conclusion is only tentative in view of the high variance among participants. Experiment 2 showed analogous results: Both beliefs and happiness were ascribed most strongly to biological humans, and ascriptions of happiness to robots or cyborgs were less common than ascriptions of beliefs.

Darwin's Dangerous Idea (updated as The Library of Mendel)

From Wikipedia, the free encyclopedia

Darwin's Dangerous Idea

Cover of the first edition
Author	Daniel C. Dennett
Country	United States
Language	English
Subjects	Evolution Ethics
Published	1995 (Simon & Schuster)
Media type	Print (Hardcover and Paperback)
Pages	586

Darwin's Dangerous Idea: Evolution and the Meanings of Life is a 1995 book by Daniel Dennett, in which the author looks at some of the repercussions of Darwinian theory. The crux of the argument is that, whether or not Darwin's theories are overturned, there is no going back from the dangerous idea that design (purpose or what something is for) might not need a designer. Dennett makes this case on the basis that natural selection is a blind process, which is nevertheless sufficiently powerful to explain the evolution of life. Darwin's discovery was that the generation of life worked algorithmically, that processes behind it work in such a way that given these processes the results that they tend toward must be so.

Dennett says, for example, that by claiming that minds cannot be reduced to purely algorithmic processes, many of his eminent contemporaries are claiming that miracles can occur. These assertions have generated a great deal of debate and discussion in the general public. The book was a finalist for the 1995 National Book Award in non-fiction and the 1996 Pulitzer Prize for General Non-Fiction.

Background

Dennett's previous book was Consciousness Explained (1991). Dennett noted discomfort with Darwinism among not only lay people but also even academics and decided it was time to write a book dealing with the subject. Darwin's Dangerous Idea is not meant to be a work of science, but rather an interdisciplinary book; Dennett admits that he does not understand all of the scientific details himself. He goes into a moderate level of detail, but leaves it for the reader to go into greater depth if desired, providing references to this end.

In writing the book, Dennett wanted to "get thinkers in other disciplines to take evolutionary theory seriously, to show them how they have been underestimating it, and to show them why they have been listening to the wrong sirens". To do this he tells a story; one that is mainly original but includes some material from his previous work.

Dennett taught an undergraduate seminar at Tufts University on Darwin and philosophy, which included most of the ideas in the book. He also had the help of fellow staff and other academics, some of whom read drafts of the book. It is dedicated to W. V. O. Quine, "teacher and friend".

Synopsis

Part I: Starting in the Middle

"Starting in the Middle", Part I of Darwin's Dangerous Idea, gets its name from a quote by Willard Van Orman Quine: "Analyze theory-building how we will, we all must start in the middle. Our conceptual firsts are middle-sized, middle-distance objects, and our introduction to them and to everything comes midway in the cultural evolution of the race." 

The first chapter "Tell Me Why" is named after a song.

Tell me why the stars do shine,
Tell me why the ivy twines,
Tell me why the sky's so blue.
Then I will tell you just why I love you.
Because God made the stars to shine,
Because God made the ivy twine,
Because God made the sky so blue.
Because God made you, that's why I love you.

Before Charles Darwin, and still today, a majority of people see God as the ultimate cause of all design, or the ultimate answer to 'why?' questions. John Locke argued for the primacy of mind before matter, and David Hume, while exposing problems with Locke's view, could not see any alternative.

Darwin's Dangerous Idea makes extensive use of cranes as an analogy.

Darwin provided just such an alternative: evolution. Besides providing evidence of common descent, he introduced a mechanism to explain it: natural selection. According to Dennett, natural selection is a mindless, mechanical and algorithmic process—Darwin's dangerous idea. The third chapter introduces the concept of "skyhooks" and "cranes" (see below). He suggests that resistance to Darwinism is based on a desire for skyhooks, which do not really exist. According to Dennett, good reductionists explain apparent design without skyhooks; greedy reductionists try to explain it without cranes.

Chapter 4 looks at the tree of life, such as how it can be visualized and some crucial events in life's history. The next chapter concerns the possible and the actual, using the 'Library of Mendel' (the space of all logically possible genomes) as a conceptual aid.

In the last chapter of part I, Dennett treats human artifacts and culture as a branch of a unified Design Space. Descent or homology can be detected by shared design features that would be unlikely to appear independently. However, there are also "Forced Moves" or "Good Tricks" that will be discovered repeatedly, either by natural selection or human investigation.

Part II: Darwinian Thinking in Biology

Tree diagram in Origin

The first chapter of part II, "Darwinian Thinking in Biology", asserts that life originated without any skyhooks, and the orderly world we know is the result of a blind and undirected shuffle through chaos.

The eighth chapter's message is conveyed by its title, "Biology is Engineering"; biology is the study of design, function, construction and operation. However, there are some important differences between biology and engineering. Related to the engineering concept of optimization, the next chapter deals with adaptationism, which Dennett endorses, calling Gould and Lewontin's "refutation" of it an illusion. Dennett thinks adaptationism is, in fact, the best way of uncovering constraints.

The tenth chapter, entitled "Bully for Brontosaurus", is an extended critique of Stephen Jay Gould, who Dennett feels has created a distorted view of evolution with his popular writings; his "self-styled revolutions" against adaptationism, gradualism and other orthodox Darwinism all being false alarms. The final chapter of part II dismisses directed mutation, the inheritance of acquired traits and Teilhard's "Omega Point", and insists that other controversies and hypotheses (like the unit of selection and Panspermia) have no dire consequences for orthodox Darwinism.

Part III: Mind, Meaning, Mathematics and Morality

The frontispiece to Thomas Hobbes' Leviathan, which appears at the beginning of chapter 16 "On the Origin of Morality".

"Mind, Meaning, Mathematics and Morality" is the name of Part III, which begins with a quote from Nietzsche. Chapter 12, "The Cranes of Culture", discusses cultural evolution. It asserts that the meme has a role to play in our understanding of culture, and that it allows humans, alone among animals, to "transcend" our selfish genes. "Losing Our Minds to Darwin" follows, a chapter about the evolution of brains, minds and language. Dennett criticizes Noam Chomsky's perceived resistance to the evolution of language, its modeling by artificial intelligence, and reverse engineering.

The evolution of meaning is then discussed, and Dennett uses a series of thought experiments to persuade the reader that meaning is the product of meaningless, algorithmic processes.

Von Kempelen's chess automaton, discussed in chapter 15.

Chapter 15 asserts that Gödel's Theorem does not make certain sorts of artificial intelligence impossible. Dennett extends his criticism to Roger Penrose. The subject then moves on to the origin and evolution of morality, beginning with Thomas Hobbes (who Dennett calls "the first sociobiologist") and Friedrich Nietzsche. He concludes that only an evolutionary analysis of ethics makes sense, though he cautions against some varieties of 'greedy ethical reductionism'. Before moving to the next chapter, he discusses some sociobiology controversies.

The penultimate chapter, entitled "Redesigning Morality", begins by asking if ethics can be 'naturalized'. Dennett does not believe there is much hope of discovering an algorithm for doing the right thing, but expresses optimism in our ability to design and redesign our approach to moral problems. In "The Future of an Idea", the book's last chapter, Dennett praises biodiversity, including cultural diversity. In closing, he uses Beauty and the Beast as an analogy; although Darwin's idea may seem dangerous, it is actually quite beautiful.

Central concepts

Design Space

Dennett believes there is little or no principled difference between the naturally generated products of evolution and the man-made artifacts of human creativity and culture. For this reason he indicates deliberately that the complex fruits of the tree of life are in a very meaningful sense "designed"—even though he does not believe evolution was guided by a higher intelligence. 

Dennett supports using the notion of memes to better understand cultural evolution. He also believes even human creativity might operate by the Darwinian mechanism. This leads him to propose that the "space" describing biological "design" is connected with the space describing human culture and technology.

A precise mathematical definition of Design Space is not given in Darwin's Dangerous Idea. Dennett acknowledges this and admits he is offering a philosophical idea rather than a scientific formulation.

Natural selection as an algorithm

Dennett describes natural selection as a substrate-neutral, mindless algorithm for moving through Design Space.

Universal acid

Dennett writes about the fantasy of a "universal acid" as a liquid that is so corrosive that it would eat through anything that it came into contact with, even a potential container. Such a powerful substance would transform everything it was applied to; leaving something very different in its wake. This is where Dennett draws parallels from the “universal acid” to Darwin’s idea:

...it eats through just about every traditional concept, and leaves in its wake a revolutionized world-view, with most of the old landmarks still recognizable, but transformed in fundamental ways.

While there are people who would like to see Darwin’s idea contained within the field of biology, Dennett asserts that this dangerous idea inevitably “leaks” out to transform other fields as well.

Skyhooks and cranes

Dennett uses the term "skyhook" to describe a source of design complexity that does not build on lower, simpler layers—in simple terms, a miracle. 

In philosophical arguments concerning the reducibility (or otherwise) of the human mind, Dennett's concept pokes fun at the idea of intelligent design emanating from on high, either originating from one or more gods, or providing its own grounds in an absurd, Munchausen-like bootstrapping manner.

Dennett also accuses various competing neo-Darwinian ideas of making use of such supposedly unscientific skyhooks in explaining evolution, coming down particularly hard on the ideas of Stephen Jay Gould.

Dennett contrasts theories of complexity that require such miracles with those based on "cranes", structures that permit the construction of entities of greater complexity but are themselves founded solidly "on the ground" of physical science.

Reception

In The New York Review of Books, John Maynard Smith praised Darwin's Dangerous Idea:

It is therefore a pleasure to meet a philosopher who understands what Darwinism is about, and approves of it. Dennett goes well beyond biology. He sees Darwinism as a corrosive acid, capable of dissolving our earlier belief and forcing a reconsideration of much of sociology and philosophy. Although modestly written, this is not a modest book. Dennett argues that, if we understand Darwin's dangerous idea, we are forced to reject or modify much of our current intellectual baggage...

Writing in the same publication, Stephen Jay Gould criticised Darwin's Dangerous Idea for being an "influential but misguided ultra-Darwinian manifesto":

Daniel Dennett devotes the longest chapter in Darwin's Dangerous Idea to an excoriating caricature of my ideas, all in order to bolster his defense of Darwinian fundamentalism. If an argued case can be discerned at all amid the slurs and sneers, it would have to be described as an effort to claim that I have, thanks to some literary skill, tried to raise a few piddling, insignificant, and basically conventional ideas to "revolutionary" status, challenging what he takes to be the true Darwinian scripture. Since Dennett shows so little understanding of evolutionary theory beyond natural selection, his critique of my work amounts to little more than sniping at false targets of his own construction. He never deals with my ideas as such, but proceeds by hint, innuendo, false attribution, and error.

Gould was also a harsh critic of Dennett's idea of the "universal acid" of natural selection and of his subscription to the idea of memetics; Dennett responded, and the exchange between Dennett, Gould, and Robert Wright was printed in the New York Review of Books.

Biologist H. Allen Orr wrote a critical review emphasizing similar points in the Boston Review.

The book has also provoked a negative reaction from creationists; Frederick Crews writes that Darwin's Dangerous Idea "rivals Richard Dawkins's The Blind Watchmaker as the creationists' most cordially hated text."