IB Philosophy 6.2.2 Explanations of the Self Notes

Biological and Biochemical Explanations

1. One of the most ambitious claims in the philosophy of science is that everything about living organisms, including human beings, can be fully explained in terms of physics and chemistry. This idea sits at the heart of the question: is it possible to reduce all life processes to biochemical reactions?
2. Molecular biology offers a powerful model for this approach. Since the discovery of DNA's structure by Watson and Crick in 1953, many biologists have argued that genetic information encoded in DNA (the molecule that carries the instructions for building and running a living organism) provides the fundamental blueprint for all living processes, from cell division to brain development.
3. Biochemical reductionism holds that complex biological phenomena, including emotion, consciousness, and selfhood, are ultimately nothing more than chemical interactions between molecules.
4. On this view, what we call the 'self' is the product of brain chemistry: neurotransmitters (chemical messengers between nerve cells), hormones (chemical signals carried in the blood), and gene expression (which genes are switched on or off in a given cell).
5. The philosopher Francis Crick captured this position starkly in his "astonishing hypothesis": "You, your joys and your sorrows, your memories and your ambitions... are in fact no more than the behaviour of a vast assembly of nerve cells and their associated molecules." This is a direct expression of the reductionist programme applied to the self.
6. Neuroscience provides substantial empirical support for biochemical explanations.
   1. Brain-imaging studies reveal correlations between neural activity and subjective experience, while pharmaceutical interventions, such as SSRIs (antidepressants that work by increasing serotonin, a chemical that influences mood, in the brain's synapses), suggest that mental states are deeply dependent on biochemistry.
7. As discussed in 6.2.1 on cognitive science and the self, these findings challenge any conception of the self as independent of its physical substrate.

Emergence and the Critique of Strong Reductionism

1. Critics of strong reductionism point out that correlation is not identity.
   1. The fact that every mental event has a biochemical correlate does not prove that the mental event just is that biochemical process, a point closely connected to the mind-body problem explored in 1.3.2.
2. Emergence presents a middle-ground position.
   1. Emergentists accept that all biological processes are constituted by biochemical reactions, but argue that higher-level properties (like consciousness, meaning, and selfhood) arise from complex organisation and cannot be predicted or explained solely from knowledge of the parts.
3. A familiar analogy clarifies the emergentist position: individual water molecules are not wet.
   1. Wetness is a property that emerges only when enormous numbers of H₂O molecules interact, and it cannot be predicted from, or reduced to, the properties of a single molecule.
4. Similarly, emergentists argue that consciousness and selfhood arise from the complex organisation of billions of neurons, but are not properties of any individual neuron.
5. The self is a genuinely new feature that only appears at the level of the whole system. It is one you cannot predict just by studying individual neurons. It depends entirely on the physical brain, but it cannot be reduced to any single part of it.
6. The philosophical stakes here are significant: if biochemical reductionism succeeds, then the self has no special status in reality. It is just one more pattern in the physical world, no different in kind from a whirlpool or a flame.
7. This connects directly to the Unit 6 overarching question of whether all elements of the universe, including human action, are ultimately determined.
8. Genetic determinism, which holds that genes alone determine behaviour and identity, gained popular traction through media coverage of studies like those linking the MAOA gene to violent behaviour.
   1. Headlines proclaimed the discovery of a 'warrior gene,' implying that carriers were biologically destined for aggression.
   2. Subsequent research revealed a far more complex picture: the MAOA-violence association appeared only in individuals who had also experienced severe childhood maltreatment, suggesting a gene-environment interaction rather than genetic determination.
9. Research in epigenetics (the study of how environmental factors can switch genes on or off without altering the underlying DNA sequence) further undermined simple determinism, showing that biology and experience shape each other.
10. Most contemporary biologists reject strong genetic determinism, but the debate illustrates a philosophically important question: if the self were entirely determined by its genetic blueprint, personal identity would reduce to a biological given rather than something shaped through experience, choice, and social interaction.

Teleological and Reductive Explanations

1. A central debate in the philosophy of biology concerns the distinction between two fundamentally different styles of explanation. Reductive explanations work from the bottom up, explaining wholes in terms of their smallest components.