Locke addresses intuition-breaking cases with a surprising dedication to his settled definition. A drunk man, having lost his memory in a black out, is not the same as the sober person from the night before. He advocates for the possibility that two people, each with their own PsyCon, could both take turns living in the same body. In another example, while he offers no mechanistic way for this to occur (he finds the idea absurd) if someone remembers being Socrates (rather than imagining himself as being Socrates) then he is Socrates, even if the two physical bodies are distanced by two thousand years. All of these seem to run counter to some sort of “common sense” perspective on what a person is, especially in the case of drunken memory loss.
The problem of memory loss is where Reid focused his criticisms of Locke, in his case of the Brave Officer:
“Suppose a brave officer to have been flogged when a boy at school for robbing an orchard, to have taken a standard from the enemy in his first campaign, and to have been made a general in advanced life; suppose, also, which must be admitted to be possible, that, when he took the standard, he was conscious of his having been flogged at school, and that, when made a general, he was conscious of his taking the standard, but had absolutely lost the consciousness of his flogging.” (Reid, 2008, pg. 114)
Reid argues that by Locke’s account, the old general and the flogged boy must be two separate people because of the lack of PsyCon between the two persons. However, by Locke’s same logic, both the flogged boy and the old general must both be the brave officer who took the standard:
Figure 1
I would like to focus on two of Reid’s arguments for the sake of this paper. First, there seem to be situations where Locke’s rules for determining identity lead to non-intuitive answers (one person being two people). This would not be problematic in and of itself, Einstein’s relativity is intuition shattering in many ways (see his famous thought experiment in Einstein, 1949), but his ideas command the paradigm of physics because of the evidence supporting them. This, however, brings up another of Reid’s criticisms: memory is only one aspect of consciousness; the Flogged Boy probably experience strong conscious sensation with no active memories in the moment of him being punished. Reid believed that Locke was confusing evidence for PsyCon, via memory, with the continuity in and of itself. Consciousness, to Reid, cannot be tracked only by memory and cannot be the anchor of identity because of its ever-shifting nature.
We (as in, Locke apologists) might say something like this to Reid: you are correct in saying that memory and consciousness are not synonymous, and we agree with you that memory is just evidence for PsyCon! However, memory is the only form of evidence for PsyCon. No other type of information can show us a link between conscious states, and we therefore must center memory in any question of PsyCon. Assuming memory is a valid form of evidence for PsyCon, we know memory exists and therefor have evidence for PsyCon, and by that evidence this continuity must be accounted for in any definition of personal identity. As previously stated, the only way to do this is by leveraging memory.
The issue with this argument is that memory may not be such a great form of evidence. Locke, as noted, differentiated memory from imagination, but people often confuse the two (Schacter & Loftus, 2013) and both forms of subjective experience seem to involve similar parts of our neuroanatomy (Zeidman & Maguire, 2016). Generally speaking, it is smarter to make assessments using multiple types of evidence rather than one, so centering only (what we now know to be shaky) memory is problematic, per false murder convictions which rely only on eyewitness testimony rather than DNA, testimony, a confession, and fingerprints on the weapon. If memory cannot stand, and there is good reason to think it cannot stand alone, Locke’s whole theory may be vulnerable to Reid’s arguments.
However, other forms of PsyCon exist which may bolster memory. Friston’s free energy principle, coming from neurology and physics rather than philosophy, defines identity over time in the form of an ever-updating model of beliefs (Friston, 2010) which do not require recall. Friston conceptualizes organisms in an abstract fashion, using Markov chains and Bayesian mathematics, in a manner which is reminiscent of Leibniz’s monads. Organisms are conceptualized as separated from the rest of the universe by “Markov blankets,” a mathematical construct which distinguishes beings from each other by their Bayesian predictions of the rest of the universe. These beliefs evolve as identity-holding models of the world over time as the being in question interacts with its environment. If the free energy principle is accurate, mathematically tracked beliefs may be an independent form of evidence for PsyCon.
Figure 2
Identity as defined by Markovian models (Clark, 2017).
The brain itself cannot be ignored in the question of PsyCon. Per Olson (2003), every person we are aware of seems to be a human animal (with a brain). The seemingly irrefutable evidence minds rely on the brain means that the existence of the same brain-substance, over time, also stands as evidence for PsyCon alongside memory and beliefs. The brain is physical, memory is subjective, and Fristonian beliefs are tracked mathematically. Add a social aspect, the verbal expression of “I” to others, and we have four forms of evidence for PsyCon instead of Locke’s lone criterion.
Physical intuitions about the space around us require information from multiple channels: sight, sound, smell, etc. Similarly, our abstract intuitions seem to require multiple forms of confirmation to feel comfortable with rational categories. By requiring more forms of evidence to establish PsyCon, not only do we protect our intuitions from confusion, we also better follow in the tradition of evidence-focused empiricism, of which Locke was a founder. We can even develop a new schema of identity-labels from this angle: “non-identity,” “ambiguous identity,” and “clear identity.” When someone shares no forms of evidence of identity with another person, we can say they are in a non-identity relationship with the other being. With one to three pieces of evidence, cases of identity become ambiguous, as we see time and time again in strange thought experiments. Ambiguity is not much of a problem in the abstract, but drives us to investigate further if we meet the problem in real life. If all four pieces of evidence I outlined above are present, we can claim someone maintains identity over time, beyond a reasonable doubt.
References
Clark, A. (2017). How to Knit Your Own Markov Blanket: Resisting the Second Law with Metamorphic Minds. Philosophy and Predictive Processing.
Einstein, A. (1949). Autobiographical Notes. New York: Tudor Publishing.
Friston, K. (2010). The free-energy principle: a unified brain theory? Nature reviews neuroscience, 11(2): 127-138.
Locke, J. (2008). Of Identity and Diversity. In J. Perry, Personal Identity (pp. 33-52). Berkeley: University of California Press. (First published in 1694 in the second edition of Essay Concerning Human Understanding).
Olson, E. T. (2003). An Argument for Animalism. In R. Martin, & J. Barresi, Personal Identity (pp. 318-334). Oxford: Blackwell.
Reid, T. (2008). Of Mr. Locke's Account of Our Personal Identity. In J. Perry, Personal Identity (pp. 113-118). Berkeley: University of California Press. (First published in 1785 in Essays on the Intellectual Powers of Man).
Schacter, D. L., & Loftus, E. F. (2013). Memory and Law: What Can Cognitive Neuroscience Contribute? Nature Neuroscience, 16(2): 119-123.
Zeidman, P., & Maguire, E. A. (2016). Anterior hippocampus: the anatomy of perception, imagination and episodic memory. Nat Rev Neurosci, 17(3): 173-182.
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