Solipsism—Do Others Exist?


SOLIPSISM IS A PHILOSOPHICAL CONCEPT that considers the nature of self-awareness and reality, in particular the existence of other conscious minds. The term comes from the Latin words “solus” (alone) and “ipse” (self). Solipsism posits that only your own mind is certain to exist. Everything else, including the external world and other minds, may be nothing more than illusions. 

Solipsism’s roots trace back to thinkers like René Descartes and George Berkeley. Descartes, in his famous statement “Cogito, ergo sum” (I think, therefore I am), highlighted that self-awareness is a sure thing. Meanwhile, Berkeley, argued for idealism, the belief that reality is fundamentally a mental construct. These early ideas laid the foundation for Solipsistic thought.

Let’s consider the key principles of Solipsism:

1. Cogito Argument: Solipsism begins with the undeniable certainty of one’s own existence—the “I” that thinks, perceives, and experiences. This is difficult to argue, although argue is exactly what some critics do.

  • Circular Reasoning: One criticism of the Cogito Argument is that it relies on the existence of a thinking self to prove the existence of a thinking self. In other words, the conclusion (“I am”) is already implicit in the premise (“I think”). Critics argue that this circular reasoning undermines the argument’s validity.
  • Ambiguity of “I”: The term “I” in the Cogito Argument is ambiguous. Descartes assumes a clear and distinct self without analysing what this “I” really consists of. Modern philosophy and psychology suggest that the self is a complex and multifaceted concept, which challenges the simplistic notion of self that Descartes’ argument relies upon.
  • Doesn’t Establish the Nature of Existence: Even if we accept that thinking implies existence, the Cogito Argument doesn’t tell us anything about the nature of that existence. It doesn’t prove the existence of a physical body, the external world, or other minds. It only establishes the existence of a thinking self without providing a foundation for our knowledge of the external world. For example, when dreaming, the sense of self is very real, but the experiences we are having are not.
  • Dependence on Language: Descartes’ argument relies on language and the proposition “I think.” Critics argue that language is a social construct, and the understanding of self and existence might not be as clear-cut and language-dependent as Descartes assumes.
  • Dependence on Conscious Thought: The Cogito Argument depends on conscious thought, which raises questions about individuals who are not conscious, such as during dreamless sleep or under anaesthesia. If existence is tied to conscious thought, does a person cease to exist during unconscious states?
  • Existence vs. Identity: The Cogito Argument proves existence (“I am”) but doesn’t establish the identity of the self. It doesn’t tell us who the “I” really is, what constitutes personal identity, or how identity is maintained over time.

Returning to the key principles of Solipsism:

2. The Problem of Other Minds: Solipsism is sceptical as to whether other minds exist or are merely figments of one’s imagination.

  • Empathy and Similarity of Behaviour: One argument against the Problem of Other Minds points to the observable similarities in behaviour and experiences among different individuals. When someone exhibits behaviours and expressions that resemble our own, if they are happy, sad, in pain, or excited, it’s reasonable to assume they are experiencing similar mental states. Empathy, the ability to understand and share the feelings of others, suggests a commonality of emotions and mental experiences among beings. On the other hand, if we view others as mere illusions or simulations, it could lead to us viewing their feelings and sensitivities as lacking any value.
  • Evolutionary Basis: From an evolutionary perspective, social animals, including humans, have developed the ability to understand and respond to the emotions and intentions of others. This capacity has provided significant advantages in cooperation, communication, and survival. The evolution of social behaviours implies a shared cognitive and emotional framework among members of the same species. Again, if we view others as if they don’t really exist, it undermines this cohesive social framework. The belief that other minds are uncertain raises ethical questions about how one should treat others. If their existence is in doubt, what moral obligations do Solipsists have?
  • Linguistic Communication: Language plays a crucial role in demonstrating the existence of other minds. Through language, individuals can express their thoughts, emotions, and intentions to others. Linguistic communication allows us to gain insights into the inner lives of others, providing evidence of their mental states and consciousness. The ability to communicate about subjective experiences implies the presence of subjective experiences in others.
  • Neuroscientific Understanding: Advances in neuroscience have provided insights into the neural mechanisms underlying consciousness and emotions. While the exact nature of consciousness is still a topic of active research (is it an emergent property of the brain, or the very fabric of the cosmos?), the discovery of neural correlates of mental states suggests a biological basis for experiences. Studying the brain activity associated with emotions and thoughts supports the idea that similar processes occur in the brains of different individuals, supporting the existence of other minds. However, since Solipsism challenges the very nature of reality, it follows that if you can’t be certain about the existence of the external world, the validity of scientific, empirical, and experiential knowledge is called into question.
  • Pragmatic Assumption: Lastly, while it is true that we cannot have direct access to the inner experiences of others, assuming the existence of other minds is a pragmatic necessity for social interactions and the functioning of society. We operate on the assumption that others have minds and experiences similar to ours because this assumption is essential for communication, cooperation, and building meaningful relationships. If we reduce our reality down to just us as the conscious participant, it makes for a very lonely existence. Solipsism, when embraced fully, can lead to a profound sense of isolation, where genuine connection with others becomes impossible due to the notion that they don’t actually exist.

So while the Problem of Other Minds raises valid philosophical questions, the shared behaviours, evolutionary basis, linguistic communication, neuroscientific understanding, and pragmatic necessity provide reasonable grounds to believe in the existence of other minds similar to our own. These factors collectively address the scepticism associated with this philosophical challenge.

3. Reality as a Mental Construct: Solipsism questions external reality, suggesting that the world and everything in it might be just a creation of one’s own mind. There are several arguments against the idea that reality is solely a mental construct:

  • External Consistency: One of the primary arguments is the consistent and objective nature of the external world. If reality were solely a mental construct, it would be subjective and differ from person to person. However, there are consistent and measurable phenomena in the external world that remain the same regardless of individual perceptions. Scientific laws, mathematical principles, and physical constants seem to demonstrate the objective nature of reality.
  • Shared Experiences: Reality is not limited to individual minds but is shared among people. Shared experiences, such as natural events, historical occurrences, and communal observations, provide evidence that reality exists independently of individual mental constructs. These shared experiences are often corroborated through various means, including scientific research, historical records, and collective observations, emphasising the existence of an objective reality.
  • Predictive Power: The success of scientific theories and their ability to predict future events strongly suggest an external reality that operates independently of individual mental constructs. Scientific theories, grounded in empirical evidence, have consistently demonstrated their predictive power, enabling humans to develop technologies, make accurate forecasts, and understand natural phenomena. If reality were purely mental, it is unlikely that scientific theories would consistently yield accurate predictions about the external world.
  • Independent Existence of Physical Objects: The existence of physical objects that can be observed, measured, and interacted with provides evidence against the idea of reality as a mental construct. These objects exist independently of individual perceptions and continue to exist even when not being observed. For example, the laws of physics governing the behaviour of matter and energy apply consistently, indicating an objective reality that transcends individual minds.
  • Evolutionary Perspective: From an evolutionary standpoint, the human mind has evolved to perceive and understand the external world accurately. Our senses have developed to interact with an objective reality, allowing us to navigate our environment, locate resources, and avoid dangers. The correspondence between our sensory perceptions and the external world supports the idea that our mental constructs align with an objective reality.

The external consistency of the world, shared experiences, the predictive power of scientific theories, the independent existence of physical objects, and the evolutionary perspective provide strong arguments against the notion of reality as solely a mental construct. They emphasise the existence of an objective reality that exists independently of individual perceptions and mental constructions.

However, and I suspect you could see this coming, there are also arguments to support the idea that you are the only conscious entity and that others are essentially like Non-Playing Characters (NPCs) in a computer game. Simulation theory goes some way to support this idea. The concept of a simulated reality where everyone (conscious or not) shares the same database, often referred to as a collective or shared simulation, has been explored in philosophy, science fiction, and theoretical physics. In a shared simulated reality, everyone (whether real or not) has access to the same database of experiences and information. This unity of experience fosters (or at least simulates) a deep sense of connection and understanding among individuals, promoting empathy and cooperation, at least for the “real” player. These shared experiences serve as a foundation for societal understanding and harmony, as everyone has a common frame of reference. Even if it isn’t real, it works.

The philosophical idea that one’s own mind is the only thing that can be known to exist, while everything else might be an illusion, is an intriguing concept. However, proving or disproving Solipsism is challenging. The very nature of the theory makes it almost impossible to provide concrete evidence either in support of or against it. Attempts to refute Solipsism often rely on shared experiences and empirical evidence, but these can’t definitively disprove the possibility that everything, including those shared experiences, might be a creation of one’s mind. Likewise, proving Solipsism is equally elusive since any evidence offered could be dismissed as a construct of the Solipsistic mind. As a result, the jury remains out on the validity of Solipsism, leaving it as a thought-provoking, yet unresolved, concept in the realm of philosophy.

Further reading