The Paradigm Shift in Philosophical and Neurobiological Theories of Memory
Jiuru Lyu
The Science of the Forgotten: Hybrid Vigor 2022-2023 Edition
Neuroscientists have developed a theory to describe the formation of people’s memory. They not only categorize them into declarative and non-declarative memory according to the type of memory but also class them into long-term and short-term memory according to how long the memory can last in our brain. Scientists have raised and testified many theories to explain how we form, process, and consolidate memory, and it is acknowledged that the hippocampus is the responsible brain tissue. However, some questions remain unknown and controversial, such as how exactly the hippocampus processes memory, what biological molecules are involved, and so on. While those questions lack scientific evidence and explanation, philosophers have been thinking about the formation and derivation of memory for a long time, and many have developed different theories.
Among those theories, the innatism theory, by Plato Augustine, and further refined by Descartes, provides an opposite attitude as the neuroscientists, where they consider some memories (knowledge, facts, and truth) are embedded in human brains before cognition is created. Human life is a journey of unveiling those pre-set memories. On the other hand, the empiricism theory by Kant and John Locke complies with the neuroscientific perspective, where people are passive in learning and creating memories. Memory has become a hot topic in recent years, and by carefully studying different philosophers’ opinions, we can find potential direction for our scientific research.
Philosophical doctrines inspire many discoveries of scientific theories in memory, and this essay will focus on the paradigm shift from philosophical and neuroscience ideas on memories.
Philosophers played an essential role in inspiring scientific research and explanation on memory, to which ends, introducing those relevant philosophical thoughts is necessary before we proceed to memory in Neuroscience. Innatism is a philosophical doctrine that our minds are born with pre-existing knowledge and ideas; thus, they think people learn or discover new knowledge from memory (Innatism, 2008). Universal accepted knowledge, such as ethical truths and notions of good and evil, is an example of innate knowledge (Innatism, 2008). In science, some mathematical truths, such as one plus one equals two, are also considered innate knowledge (Innatism, 2008). It was Plato who first raised the theory of reminiscence soul, in which they regarded the world as the existence of rationality, and people learn new knowledge from the lost memories in their souls (Plato and the reminiscence of the soul, 2018). This theory marks the origin of innatism. Then Augustine believed that experience does not exist and the certainty of knowledge derives from the inner side of human beings, which can be viewed as a development of Plato’s idea (Augustine | Internet Encyclopedia of Philosophy, n.d.).
Then, the French philosopher René Descartes raised the famous dictum “Cogito, ergo sum” (Latin: I think, therefore I am), pointing out that some principles are rooted in humans at birth (Cogito, Ergo Sum | Philosophy | Britannica, n.d.), which is regarded as the starting point of empiricism. His theory considers those opinions and knowledge from people’s hearts the most reliable principles. Other opinions come from people’s experiences or are made up by people, which is not reliable in his doctrine. This perspective is called rationalism now. So then, Leibniz developed this doctrine: all thoughts and opinions exist from people’s birth, and all opinions are already rooted in people’s hearts (Look, 2020). Like rationalism, philosophers also developed the idea of empiricism, asserting that our beliefs and memories come from our past experiences (Markie, 2023). In other words, our knowledge is derived from experimentation and anecdotes.
Inspired by rationalism and empiricism, Neuroscientists gradually defined memory as the retention of learned information. Neuroscientists classified memory into different categories: declarative and non-declarative memory, which, by definition, are distinctive from each other: Declarative memory refers to the memory of facts and events, whereas non-declarative memory includes procedural memory or memory of habits, behaviors, and skills. Sometimes, people refer to non-declarative memory as implicit memory as it results from experience; declarative memory is called explicit memory since it comes from conscious efforts. Moreover, declarative memories can be formed easily but forgotten easily, whereas non-declarative memories require repetition and practice.
Long-term and short-term memories are two types of declarative memory. Long-term memory lasts longer than short-term memory, and people can recall them after days, months, or even years. On the other hand, short-term memory is vulnerable to disruption and only lasts temporarily. Short-term memory is the most common memory we have and can be converted into long-term memory through memory consolidation. As shown by the flowchart below, parts of the sensory information can be temporarily stored as short-term memory and converted into long-term memory through the consolidation process as time goes by.
Another type of memory, working memory, is also shown in the diagram above. It is a distinct form of temporary storage that lasts for only seconds. However, working memory has a limited capacity and requires rehearsal to improve. For example, when others tell us their phone number, we can repeat it several times to keep the information in mind. The temporary memory of the number is an example of working memory. However, if other phone numbers are too long, we would have trouble memorizing them, which illustrates the limited working memory capacity. The memory of the number can be converted into long-term memory eventually, sometimes.
In comparison, innatism is opposite to the perspectives of memory in neuroscience. In neuroscience, we believe that we get information from the outside world, and then the information turns to memory. We can recall the memory from time to time when we need them. Similar to the perspective in neuroscience, the philosophers also develop the doctrine of empiricism to illustrate that our understanding of the outside world is passive (Uzgalis, 2020). German philosopher Immanuel Kant then developed this idea: he believed that knowledge comes from experience in the time dimension, but the contents of our knowledge have nothing to do with our experience. His doctrine combined innatism and empiricism because it confirmed experience’s role in our pursuit of knowledge (Rohlf, 2020).
Though how our brains process memory remains unclear to us, ongoing studies have already been targeted to explain concepts such as hippocampal processing, which is very important for us to unveil the mystery of human memory. Together with the development of modern philosophy, neuroscientists will gain inspiration from an interdisciplinary lens and use the scientific method to gradually develop theories to explain the networks in our brain – not only memory but also emotion and other aspects.
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Innatism. (2008). Psychology Wiki. https://psychology.wikia.org/wiki/Innatism. Accessed on Jan 6, 2023.
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Rohlf, M. (2020). Immanuel Kant. In E. N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Fall 2020). Metaphysics Research Lab, Stanford University. https://plato.stanford.edu/archives/fall2020/entries/kant/. Accessed on Jan 6, 2023.
Uzgalis, W. (2020). John Locke. In E. N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Spring 2020). Metaphysics Research Lab, Stanford University. https://plato.stanford.edu/archives/spr2020/entries/locke/. Accessed on Jan 7, 2023.
