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The Brain and the Meaning of Life 4: How Brains Know Reality


Reality and Its Discontents
This chapter seeks to establish that the world exists independently of minds, but that minds construct reality based on its interaction with it.

This chapter shows how brain science and philosophical reflection together support a kind of constructive realism, the view that reality exists independently of minds, but that our knowledge of it is constructed by brain processes (891).

Knowing Objects
Thagard makes a distinction between top down and bottom up information processing. Bottom up involves the sensory data from our eyes, ears, etc. being sent to the brain. The top down involves past experience and knowledge being used to interpret the data that comes in.

Appearance and Reality
Thagard tries to answers skepticism of our senses by pointing out that we can use multiple senses together to gain consistent information about what we experience. Given the lack of evidence for hallucination, it becomes fair to presume reality. But wouldn’t these experiences be evidence for hallucination as much as reality? I don’t know if Thagard answers this well.

Thagard also puts forward testimony of others as a way to verify reality. We trust testimony by way of inference to the best explanation. It is a better explanation of reports of Mount Everest that it exists, than that mass delusion caused the reports.

Concepts are mental represantations- once they were thought to be definable strictly by giving necessary and sufficient conditions, like with a triangle. Now we seem to know that we don’t really store concepts like that. The example of a chair is perfect. There really aren’t necessary or sufficient conditions. Instead, there might be a prototype chair, from which we derive relative chairness, or even a list of chair examples in our minds.

In contemporary cognitive science, concepts are mental representations, which the previous chapter implies are brain representations (1006).

Knowledge Beyond Perception

defenders of the phlogiston theory desperately suggested that phlogiston has negative weight, in an attempt to explain why objects gained weight while burning and supposedly losing phlogiston. Hence we want to evaluate the best explanation not only by considering how many facts each theory explains, but also by considering how many extra assumptions it makes in order to generate these explanations (1092).

Coherence in the Brain
Pretty hard to understand: Thagard is trying to use models of inhibition and excitation to represent inference to the best explanation. Some facts cohere with some facts, and don’t cohere with others. These facts will excite what they cohere with, and inhibit what they don’t. This pattern of excitation and inhibition of different propositions is (somehow?) how inference to the best explanation occurs in the mind among neurons.

Coherence and Truth

There are no foundations for knowledge, even though the overall reliability of perception justifies recognizing that the results of observation should have a degree of priority in the maximization of coherence (1188).

I advocate a kind of coherentism, the view that beliefs are justified by how well they fit with other beliefs and with sensory experience (1190).

we can construe truth as correspondence between mental representations and aspects of reality (1203).

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