The challenges of cognitive science to philosophy

Liu Xiaoli  (Renmin University of China，Beijing, 100872)

Cognitive science in the broad sense is a group of disciplines including philosophy, psychology, neuroscience, artificial intelligence, linguistics, anthropology, and education. Due to its important position ever since the foundation of cognitive science, philosophy has always coexisted with the empirical studies of cognitive science. And in this partnership, philosophy and cognitive science have also developed a "two-way challenge effect": On the one hand, philosophy has played an indispensable role of foundation laying, scrutinizing and criticism in the establishment and ongoing revision for various cognitive science research programs. In this way it has helped propel the significant progresses achieved in cognitive science, especially the development of the first generation research program that took representation–computation as its core into the second generation research program characterized by embodiment, and greatly promoted the empirical research in cognitive science. On the other hand, empirical research and philosophical debates developed within the cognitive science put forward new challenges to philosophy. The challenges gave rise not only to the various new forms of physicalism and dualism in philosophy, but also to the various research directions of naturalist philosophy. All this has had a significant impact upon the discipline’s basic conceptual framework，problem domains, and research methods．In the following, focusing on the study of consciousness, I will discuss the two-way challenge effect between the empirical research on cognitive science and philosophy, and prescribe a response for philosophy in face of these challenges.

I. How to explain consciousness and conscious experience? 
Thagard noted in his reflections on the long-time dominant program of computationalism in cognitive science that the computational-representational understanding of mind (CRUM) as the central hypothesis of computationalism is facing important challenges from seven directions: emotion, consciousness, external world, body, society, dynamic systems, and quantum computation. I think that these challenges are also directed at philosophy. The reason is that the greatest difficulty in explaining the nature of mind by contemporary science and philosophy is to handle the “hard problem of consciousness”  and the problem of the “explanatory gap” : whether or not natural science that deals with physical and neurobiological phenomena can explain the phenomenon of consciousness, and is there a gap between the explanation of consciousness and the explanation of physical and neurobiological phenomena? 
The challenges are precisely the hard problem of consciousness and subjective consciousness experience that philosophers and cognitive scientists have to deal with. Faced with these challenges, current research on cognitive science takes mainly three approaches: The first is to insist on the computationalist program and extend the CRUM to CRUMBS (Computational-Representational Understanding of Mind, Biological-Social). The second is to develop the 4EC approach of the second-generation cognitive science research program, that is the embodied, embedded, extended, enactive cognition approach of research. And the third approach is to emphasize the self-organizing dynamic systems. Accordingly, there are several new trends developed in cognitive science: Neuroscience experiments searching for the neural correlates of consciousness have increasingly grow into the core methods in many disciplines; The roles played by body and socio-cultural environment in cognitive processes are more and more emphasized;  Consciousness is taken to be a phenomenon of life and researchers are paying more and more attention to the evolutionary biological explanation of cognition; Conceptions of autopoiesis and self-organization are introduced, and the complex dynamic system theory is advocated; Cognitive mechanisms are explained by appealing to the quantum mechanics theory. These new trends stimulate and deepen contemporary philosophical studies in various aspects, and bring new perspectives from which to re-examine the philosophical problem of ‘how matter and consciousness are related’. In facing these various complex forms of debate we have to rethink whether or not the problems like the ‘hard problem of consciousness’ should be left entirely to the empirical study of cognitive scientists, and whether or not the natural sciences, with physics as their core discipline, could bridge the ‘explanatory gap’.
There are three characterizations of the consciousness-matter ‘gap’: ontological, epistemological, and semantic. The ontological gap implies that the objects of consciousness, conscious states and processes are different from those of the physical. The epistemological gap indicates that the cognition and explanation of conscious phenomena differ from that of the physical phenomena. The semantic gap suggests that different subjects may have different conscious experiences, and the difference between the first-person and the third-person perspectives may result in different meanings of the same linguistic statement. From the reductive perspective, these three gaps correspond to the ontological, epistemological, and semantic irreducibility of the former to the latter. 
By the beginning of the 20th century, the Cartesian substance dualism had been abandoned by most philosophers. Along with the birth of the relativity theory and the quantum mechanics, traditional materialism that takes the material entities to be the only reality was replaced by some new patterns of physicalism. The following statement may characterize today’s physicalist position: ‘Physicalism is the thesis that everything is physical, or as contemporary philosophers sometimes put it, that everything supervenes on the physical.’ Commitment to the causal closure of the physical world, that is all physical effects must have physical causes, is basic to the physicalist position. In addition to the hostile questioning of ‘Hemple’s dilemma’, the strongest criticism of the physicalist position came in the form of the following three anti-physicalist knowledge arguments: Nagel’s bat argument (T . Nagel, 1974), Jackson’s black-and-white Mary argument (F. Jackson, 1982), and Chalmers’ zombie argument (D. Chalmers, 1996).  These arguments have been made to reveal in a deeper level why physicalism will encounter the epistemological dilemma: even if you could get all of the physical knowledge, you still cannot explain the unique conscious experience. For example, the physical knowledge you have can make you understand bat behavior, but you can neither experience like a bat, nor describe bat experience. Can a person acquired all the physical knowledge in a black-and-white world explain her experience in seeing a red tomato in the sun by using her knowledge? Will she gain any new physical knowledge from this experience? Is there any guarantee that a person with exactly the same physical conditions and behaviors as yours has exactly the same conscious experiences? Levine (J. Levin, 1983) has noted that no matter how many brain facts we know, we still cannot conceptually explain why a specific complex brain state or process will let people have a particular conscious experience, such as pain, rather than other conscious experiences, such as joy, and so on. Even if physicalism is ontologically true, it will still be in a state of perplexity due to the epistemological ‘explanationary gap’. It can be said that neither physicalism nor anti-physicalism have enough evidence to eliminate the ‘explanatory gap’. And various anti-physicalist positions are mostly entangled with a certain form of dualism. 

II. Challenges from neuroscience     
Although the ‘Explanatory Gap’ is still a major philosophical threat to physicalism, many neuroscientists who are not satisfied with the metaphysical debates do not believe that it poses a real challenge to the work of scientists. In the 1990s, as cognitive science research advances, scientists either apply a variety of new brain-scanning technologies to trace neuron cluster activities, or use technology derived from brain injury research to observe functions of special brain areas. The ‘scientific research of consciousness’ aims at discovering the neural mechanisms of conscious experience, and in turn bring new challenges to the ‘arm-chair’ speculative philosophy. Philosophers have to answer new questions that they have never encountered before.
Various neuroscientific studies seem to have tacitly accepted the assumption of the mind-brain identity theory, which is a typical physicalist position claimed by J. C. Smart, U. T. Place, and H. Feigl in the 1950s.  They held that: (1) all psychological states are specific neurological states; (2) all psychological properties can be reduced to neural properties; and (3) through detailed descriptions of neurological characteristics and states, the phenomenon of consciousness can be explained.
For example, Crick declared that “‘You’, your joys and your sorrows, your memories and your ambitions, your sense of personal-identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules’’. Consciousness and conscious experience are only emergent properties of the nonlinear systems of neurons. In order to solve the “hard problem of consciousness”, Crick and Koch initiate the NCC approach to search for the neural correlates of consciousness in the brain. Thus, emotions, qualia, self-consciousness, and other minds, which were seen as taboo subjects in the past, have since become a major topic of neuroscientific research. As for why the objective neurological events leap to subjective consciousness with totally different nature, neuroscientists such as Edelman and Tononi believe that although conscious experience is subjective, it is a dynamic physical process of neural activities in the brain and a holistic property of the dynamic core developed through distributed interactions of the neuron population. Tononi later made an effort to explain the causal power of the measurable physical substrate, a necessary condition of consciousness. He claims that consciousness as integrated information possesses irreducible internal holistic character in the highly complex neuron population in the brain. Neurophysiologist Libet develops a notion of Conscious Mind as a Field (CMF). He takes subjective conscious experience to be a field-effect, which is a product of appropriate and diverse neurological activities. CMF provides a medium between neural activities and the emergence of subjective experience. However, CMF does not belong to any known physical ‘field’, and cannot be described by observable physical events and known physical theories. It is only through the first-person report made by the subject of that experience, can its effect be acknowledged. Results of Libet’s neuroscientific experiments responded to philosophers’ challenge to physicalism, and at the same time they forced philosophers to rethink justifiable reasons for their first-person philosophy. How can philosophers insist the thesis of the privacy and authority of self-knowledge? How can they protect traditional philosophical domains of subjectivity and so on from erosion? 
Today, neuroscientists even use more and more sophisticated technologies, such as the functional magnetic resonance imaging technology and brain injury technology, to find the neural mechanism to explain morality and value. They believe that the philosophical questions such as whether or not there is free will and whether rational consideration or intuitive emotion has priority in making moral judgments can be answered by scientific experiments. Then, are there any problems facing the mind-brain identity theory, the default premise of these empirical studies? We will see, according to another analysis, that the explanation that ascribes consciousness and conscious experience entirely to neural activities in the brain is just another variant of Cartesian dualism.

III. Neo-dualism’s challenge to the premises of the neuroscientific theories
Most philosophers today no longer hold the Cartesian dualist position. However, in recent years, the deep controversies triggered by the ‘hard problem of consciousness’ and the ‘explanatory gap’ problem seem to bring dualism back to philosophy, but the focus of attention is no longer substance dualism, but neo-dualism in different forms.  The development of these new forms of dualism shows that the ontological and epistemological disputes in philosophy inspired by cognitive science studies are more and more complicated. These disputes also give challenge to neuroscientists’ working hypotheses. Though most scientists tacitly accept the physicalist premise, they either intentionally or unintentionally involve some sort of the neo-dualism in their scientific research paradigms.   
Various neo-dualisms are expressed in the above mentioned three anti-physicalist epistemological arguments. These arguments all tacitly admit the irreducibility of qualia and accept the following four premises: (1) Different from observable behaviors and physical phenomena, qualia reside in the private sphere and have first-person status ontologically. (2) Conscious experience is a subjective experience and is accessible only through subjective introspections. (3) Conscious experience can only be directly accessed by subjects of the experiences, whereas other people have only indirectly access to it. (4) Psychological predicates are only names representing internal entities, such as psychological objects, psychological states, psychological activities, and psychological processes, and grasping their meaning is independent of the concepts that describe external behaviors. It is clear that these premises are the variants of the premises used by Descartes in his justification of substance dualism. Chalmers explicitly declared that his naturalistic property dualism is of that kind. He admits that everything in the world is physical, but different from the reductive physicalism, he insists that consciousness has unique psychological properties that differ from physical properties, and the special quality of mind, in particular the qualia of subjective experience, cannot be reduced a priori to physical properties in logical and metaphysical sense and cannot be explained by physical theories. In fact, this property dualist position is taken by many scientists. Tononi believe that my conscious experience just is. Indeed, that my experience here and now exists—it is real or actual—is the only fact I am immediately and absolutely sure of, as Descartes realized four centuries ago. Moreover, my experience exists from its own intrinsic perspective, independent of external observer.
In the view of the biophysiologist Bennett and philosopher Hacker, attributing psychological properties to the brain, a position widely held by scientists attempting to find the neural correlates of consciousness, can be seen as an objectionable new form of dualism. They think that this position is fallacious in two respects. On the one hand, it distinguishes between the world in the brain and the world outside, which is equivalent to the making of a commitment to the conception of the ‘brain entity’ separated from the physical world. On the other hand, it commits a ‘mereological fallacy’, that is, to reduce the ‘such… and such’ psychological states to the ‘such…and such’ neurological states, and to ontologically reduce a human being as a whole to his neural systems and to ascribe properties  of a whole human being merely to his brain and parts of his brain. According to Edelman, Tononi, Crick, and Glynn, the consciousness is the product of a special kind of brain processes, and  the current properties of consciousness are the properties of brains. However, Bennett and Hacker pointed out that the ascription of conscious experiences or psychological properties entirely to the brain is isomorphic with the Cartesian conception of ascribing psychological properties to some internal mental entities, and what the neuroscientists do is only to replace the Cartesian mind with a material brain, whereas the basic logical structure of dualism is still retained. This mereological fallacy leads to a confusion between philosophical concepts and scientific issues. A danger lies in this confusion: the empirical studies of the hard problem of consciousness by the NCC approach might raise questions containing erroneous conceptions and influence the scientific explanations of experimental results and their theoretical implications. This is precisely the key point in the philosophical foundations of cognitive science that is questionable. To ascribe mental properties to the internal entities of the brain and to take meaning to be merely in the brain is just like to admit the ghost in machine. No wonder the view is also called ‘neo-Cartesianism’. 
In fact, such controversial issues are many: Is dualism definitely opposite to physicalism? What is the profound meaning of labeling a certain type of mind-brain identity theory neo-dualism? If contention of the irreducibility of mental or psychological properties implies an ontological dualism, then are various naturalistic positions, such as functionalism, non-reductive physicalism, emergent physicalism, and physicalism build on the theory of the hierarchical structure of the world all have some relations to the Neo-dualism? It can be seen that the perplexities involved in the present disputes on dualism have go far beyond the traditional conceptual framework of philosophy. Current debates on dualism initiated in cognitive science studies, including the change of philosophical problem domains, the change of the conceptual framework by which people describe the world, the challenges of Neo-dualism to various materialism, old and new, as well as the profound theoretical issues related to the ontological and epistemological debates on consciousness and conscious experience, are precisely the new challenges that philosophers have to take.
   
IV. How does the enactive cognition approach eliminate the “explanatory gap"?
As discussed previously, neither reductive or non-reductive physicalism, nor the various neo-dualisms solve the "hard problem of consciousness" and eliminate the “explanatory gap”. The essential nature of human beings as organisms may really be neglected in the mereological fallacy committed by the neo-dualisms. Therefore, the representatives of the 4EC approach in the second-generation cognitive science, such as Varela, Thompson, and Noë, established a new enactive cognition approach from a holistic perspective.
In their view, the entanglements of the ‘hard problem of consciousness’ - the ‘explanatory gap’ –the ‘neo-dualism’ are all derived from the misleading classic computationalist program of the first-generation Cognitive Science. The Program has three basic assumptions: (1) Cognitive states are the computational relations of computation-representations [with mental content]; (2) Cognitive processes are the computational manipulations of computation-representations [with mental content]; (3) The structures and representations of computation are digital [symbolic]. It is obvious that the philosophical assumption of the dualist division of the mental and the physical is implied in the cognitive computationalism. Moreover, when this cognitive computationalism takes mental processes as symbolic computations in the brain, consciousness and subjective conscious experiences are completely excluded from the conception of information-processing and the conception of Turing computation it inherited, and the mind is divided into two different domains, one involves personal subjective mental states and the other symbolic computational states in the brain. Such a separation has caused a series of the "hard problems of consciousness" which can be expressed as follows: (1) The ‘phenomenological’ mind-body problem: How does the brain as a computer have subjective conscious experience? (2) The computational mind-body problem: How does the brain accomplish computations concerning reasoning, belief, and conscious experience? (3) The mind-mind problem: What is the relation between the computational states of the mind and the subjective states of conscious experiences? It is clear that each of them is a variant of the "explanatory gap" problem. We will see in the following how the enactive cognition approach redescribes the "explanatory gap" in the ‘mind in life’ framework, and transfers it thoroughly into a unique body-body problem.
Varela and Thompson argued that there is a profound continuity between life and mind, i.e., mind is mind in life. Their claim has three implications. First of all, the most fundamental characteristic of life is autopoiesis and autonomy. These two characteristics are the internal features of a self-organized life system, and are determined by its self-organized and self-control dynamical mechanisms. Secondly, intentionality involving subjective experiences is a basic inherent feature of the ‘subjective living body’. The so-called ‘subjective living body’ is not the Cartesian physical body, but a living organism having subjective experiences of consciousness in the life-world. Thirdly, in the holistic sense, life encompasses three major elements: the organism, the subjectively lived body, and the life-world. In this sense, a mind is a mind in life.
It is clear that there is a significant difference between this conception of mind in life and the traditional understanding of mind in the "hard problem of consciousness" and the "explanatory gap". If the dualistic explanation of mind-body problem in the "hard problem of consciousness" is replaced by the conception of "subjective living body in life", the original mind-body problem will be converted into a body-body problem. The "explanatory gap" will be no longer a gap between two fundamentally different entities, i.e., the mind and the body, and between the mental and the physical, but a relation between the two sub-categories of life, that is, the body as a living organism and the living body active in its environment and carrying with it conscious experiences and intentional activities. Thus the absolute gap between the mental and the physical and the absolute conflictions between the two will no longer exist. A living body can be understood as states of a lived body’s activities involving conscious experiences in its environment, and consciousness is something produced when a living organism deals with its environment for subsistence. Therefore, it is not the brain that has a mind, but the living person as a whole organism and consciously dealing with the world has a mind，one kind of mental capacity. In the view of the advocates of enactivism, this explanation of consciousness and conscious experience perfectly builds a new naturalistic bridge for the "explanatory gap". The previously mentioned debates on the "hard problem of consciousness" and the "explanatory gap" are all due to the fact that people have been trapped in the whirlpool of cognitive computationalism, reductive physicalism, and dualism. And the dualistic glossary used since Descartes’ time even brings more confusions and errors. They therefore claim that to fill the "gap" the traditional dualistic glossary must be discarded. Moreover, people like Varela believe that both in psychology and in cognitive science a satisfactory research on consciousness must rely on a good first-person methodology in order for the well-trained subjects to be able to provide stable, accurate, and exquisite self-report of their conscious experiences.
Varela introduces the enactive cognition approach into the cognitive science studies and takes consciousness and conscious experiences to be something emergent from the coupling of organisms and their environments. Then consciousness is not something merely determined by brain mechanisms. This view no doubt questions and challenges the working program searching for the neural correlates of consciousness. However, since in their argumentations many metaphorical expressions, which may be advantageous theoretically but lacking practical manipulatability, are used, it is still open to debate whether or not it can really influence the empirical studies in neuroscience.

V. What should philosophy do in face of the challenges?
As mentioned earlier, compared with the classic philosophical debate on the mind-body problem, today’s debates on the "hard problem of consciousness" and the "explanatory gap" went through the 60 years’ research history of the cognitive science, and along with the development of cognitive science from the first generation to the second, conceptual frameworks used and questions raised in the philosophical studies are expanded, and research methodologies are more and more diversified and refined. Then, there is a meta-philosophical inquiry worthy of investigation: In face of the following challenges, what should contemporary philosophy do?
1. The ontological challenge
Various forms of debate related to the physicalism and the neo-dualism that arise together with the scientific studies of consciousness provide new perspectives for ontological reflections. First of all, an important ontological problem is concerned with the two different conceptions of the world: our commonsense picture takes human beings to be conscious, free, and rational agents in the world, however, according to the physical sciences, the world is material and there are no things, events, and processes that can go beyond the control of matter and energy. How can we make the two pictures consistent? Just as the intense debate between realism and anti-realism, which is developed along with the revolution of physics in the 20th century, put traditional ontological view that takes material entities to be the only entity in doubt, the empirical studies in cognitive science provide us with important resources for our reflections on the problem “what are the objects, properties, and relations of which the world is composed”. In regard to the relation between matter and consciousness, are the non-reductive physicalism such as property dualism and the theory of supervenience also acceptable? Did the debates between physicalism and all kinds of neo-dualism make a breakthrough in the traditional territory of ontology? Do we need to re-examine our ontological concepts, categories, and problems, and to reconstruct our ontological map? Secondly, can the principle of the causal closure of the physical world be abandoned? Is the causal laws described by physics the only kind of law that governs the world? Perhaps, the principle of the causal closure of the physical world is not sufficient for an explanation of how there can be life, subjective experiences of human beings, and meaning in the world. It is only a principle for explaining the physical motions in the physical world, and should not be taken as the only law for the explanation of the whole world. The causal laws of physics have already shown their inadequacy in our explanations of conscious life and the nature of human beings. Then, is the explanation that integrates the dynamical system theory in the life sciences, the reciprocal causality of dynamical systems advocated by enactivists such as Varela and Thompson, and teleology an acceptable option for explaining the nature of the mind? 
2. The epistemological challenge
First of all, problems debated in consciousness studies are obviously not merely ontological, they interwind at all times with epistemological considerations. And this is exactly one of the new theoretical characteristics of the naturalistic epistemologies developed in the late 20th century. How can human beings know the world and get to truth? Are the physical/mental and body/mind distinctions metaphysical or ontological? Or are they distinctions between the third-person and first-person perspectives in cognition? Or are they distinctions of the “ontological commitments” of theories as Quine suggested? An unavoidable epistemological question is: in regard to the various criticisms directed at dualism, can we eliminate the dualistic glossary? Does the use of the dualistic vocabularies entail the adoption of the ontological dualist position? If we give up the substance dualist position, can we still have the dualistic perspective of some form epistemologically, methodologically and semantically?
    A further epistemological issue needs to be explored is whether the "hard problem of consciousness" or the "explanatory gap" is an ontological gap, or an epistemological gap, or just a semantic gap. In explaining consciousness and the subjective features of conscious experience, what do the various views, such as the views that the mind is embodied, the mind is extended, the mind is enactive, and the mind is mind in life, mean to the study of subjectivity? Although there are different approaches of “naturalized epistemology”, they all claim to be naturalistic. Then, what are the theoretical implications, premises, and research programs of naturalism? What theoretical resources does the naturalist epistemology provide us for our reflections on traditional epistemology? What are the essential distinctions between the unique teleological explanation developed by enactivists and the causal ones?  Are the interactional causal explanations of autopoietic systems, the biological naturalistic explanations, or the explanations of the naturalized phynomenology ultimately a kind of explanation that appeals to natural causal laws in physical world?
3. The methodological challenge
From Plato to Descartes, Kant and Husserl, although philosophers sometimes made pre-science conjectures, by constructing thought experiments, most of them explored the nature of human cognition and mind in an a priori and speculative way of armchair philosophy. It is in the middle of the 20th century, with the advances made in the positivism studies, some philosophers began to adopt naturalist approaches, take philosophy to be a continuation of science, and try to doing philosophical research by using methods of natural sciences. This naturalistic tendency no doubt poses a severe challenge to the methodology of traditional philosophy. Along with their increasing awareness of the progresses made in the cognitive science, some philosophers no longer explore the nature of cognition only by speculation, and are not willing to just stand behind scientists and make philosophical inquiries afterwards. Instead, they begin to engage in empirical studies together with scientists to expand the territory of cognitive understanding. Tim van Gelder, an advocate of the cognitive dynamical theory, once vividly summarized the multiple roles philosophers play in the cognitive science: pioneer, building inspector, zen monk , cartographer, archivist, cheerleader and gadfly .  Philosophers not only use the methods of conceptual clarification and philosophical argumentation, but also take advantages of historical perspectives. Moreover, philosophers today seem to play a new role of an experimenter and carry out various philosophical experiments. Some philosophers begin to introduce psychological questionnaire, computer virtual simulation experiments, and the neuroscientific experiments to solve problems of traditional ontology, epistemology and ethics. The currently popular movement of the experimental philosophy seems to be leading a methodological revolution in the philosophy of mind and cognition. And the new directions and methodology of the naturalistic philosophy such as neuro-philosophy, neural ethics, and experimental philosophy are all flourishing. Then, what is the future of these naturalistic philosophies?
    In facing challenges coming from scientific researches, many philosophers begin to worry that as cognitive science advances and an increasing number of scientists enter into the traditional territory of philosophy, there is a risk of continuous overthrow of the traditional philosophical ideas. Philosophy can only play a role in the pre-science era. Then, will philosophers gradually lose their own territory and thus exit the stage of philosophy of cognition as science advances step-by-step in the future? I personally think that science and philosophy each has its own territory. In regard to the problem of consciousness, scientists should study the mechanisms of consciousness, psychological processes and capacities of behavior, as well as the physical, biological, and neurological basis that realize those capacities. While philosophers should study the metaphysical nature of mind, and study the mind in the relationship between mind and body, mind and persons, mind and world, and mind and meaning of life . Philosophers need not to develop scientific hypotheses which can be fully confirmed or falsified by experiments. Philosophers’ task is to make conceptual clarifications and analytical argumentations, as well as to examine, criticize and reflect from historical perspectives on the basic assumptions made in scientific research. Though scientists and philosophers often use the same terms in their research on and theoretical explanation of the mind, the objectives and implications of their study are in fact different. Philosophical questions cannot be fully handed over to scientific studies, and neuroscience is not likely to afford the whole burden of philosophical problems, and answer all of them including eternal truth and the ultimate value. Therefore, as long as the investigation of the mechanisms of human cognition is still in the process and the nature of human mind is still a mystery, there will be bright prospects for philosophers. Philosophers will not lose all their own territories as empirical studies in cognitive science advance, and need not to turn themselves into neuroscientists and artificial intelligence experts. However, in the interdisciplinary community of cognitive science, philosophy included, philosophers should respect the explanations provided by scientists, and the wisest choice for philosophers is to learn more about the works done by scientists, and work together with cognitive scientists to develop new theories, methods and conceptual frameworks in their efforts to resolve the "hard problem of consciousness". I should admit that the above discussion is a meta-philosophical reflection on the nature of the mind and cognition in relation to the "hard problem of consciousness" and the "explanatory gap" from the "two-way challenge" perspective. This reflection is still in outline and very brief. For an in-depth and systematic research, we need not only a good understanding of the results and methods of empirical studies, but also refined conceptual analysis, rigorous logic argumentation, and profound historical insights.