1. Physicalism claims that all reality is physical
2. Cognitive states exist in reality
3. Cognitive states are physical
4. Physicalism claims that there is a mind-independent physical reality
5. Physicalism claims that physicalism can be known to be true
6. Knowledge claims are cognitive states, and therefore physical
7. Therefore, to know that physicalism is true, a cognitive state must accurately map onto the mind-independent reality it is about
8. Therefore, physicalism requires that at least some mind-dependent cognitive states accurately correspond to mind-independent physical reality
9. That mind-dependent cognitive states accurately correspond with mind-independent reality is not automatically justified
10. Any justification used to establish this correspondence is itself another cognitive state
11. Therefore, the justification is itself another physical cognitive state
12. Therefore, physicalism must rely on a physical cognitive state to justify the claim that physical cognitive states reliably track mind-independent physical reality
13. This is circular, as it presupposes the point in question
14. Therefore, physicalism cannot non-circularly justify the claim that cognitive states accurately represent mind-independent physical reality
15. Hence, physicalism cannot justify access to reality beyond mind-dependent states
16. Hence, physicalism cannot justify the claim that all reality is physical
17. But physicalism claims that physicalism can be known to be true
18. Therefore, physicalism contradicts its own claim to knowledge
19. Therefore, physicalism is false

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By 15, physicalism leads to epistemic solipsism

By physicalism, I mean ontological physicalism. Agnosticism to what mind-independent reality is like is not compatible with physicalism.

This argument is agnostic to what epistemological framework you use. Corresponding to an external physical state is NOT the correspondence theory of truth. It means regardless of what you call it, the cognitive state behind the knowledge claim and what the knowledge claim is about are both physical states. Hence, physicalism has to justify why the former accurately maps onto the latter. They can’t do this without circularity.

The only way to avoid this is by asserting as a brute fact that some cognitive states accurately map onto physical reality. Not only is this circular (presupposes physicalism is true), it leads to panpsychism when taken to its logical conclusion.

I am trying to understand this word, but there is no direct English translation.

The "essence of man" is the best I could find. It seems to be an abstract concept of what makes a person, a person?

I'd appreciate alternate perspectives and how this is applied in German language/culture. Thanks

For some reason, physicalists really struggle with these three concepts when discussing the nature of consciousness:

1. The difference between science and physicalism: physics vs metaphysics
2. The difference between the objectivity or validity of evidence, and the conditions required for evidence to be objective or valid
3. The fact that third-person description presupposes first-person experience: neuroscience vs experience

Clearing these up will not automatically make everyone agree, but it would vastly improve discourse here. I continuously see the same mistakes.

Physics vs Metaphysics

Physics = an empirical science.

Physicalism = a metaphysical claim about what the science shows.

Physics studies mathematical and causal relations within phenomena. It cannot prove that reality is "physical", cos science is explicitly neutral about the ultimate nature of what it studies.

The moment you use physics to make claims about reality in itself, you have moved beyond physics and into metaphysics.

People falsely attribute the success of the scientific method to physicalism, or act as though physics gives credence to physicalism, despite there being no necessary connection between them. They are completely different fields. You need to let go of the idea that being a physicalist means being on the side of science.

Evidence vs Conditions for Evidence

I have seen countless conversations reach a stalemate cos the physicalist can't engage with this meta-level argument.

They say, "I only believe what the evidence shows." The other person replies that there's nothing wrong with evidence, but the discussion concerns the conditions that make the objectivity/validity of evidence possible in the first place.

The physicalist then usually does one of two things:

a) They strawman the idealist as being anti-science. This is ironic because the physicalist often accepts science through blind trust while refusing to examine its epistemological grounding. The idealist has a deeper appreciation of science by recognising its purpose and limits.

b) They simply stop engaging with the argument.

Nobody is denying the usefulness or validity of empirical evidence.

The issue arises when people stretch empirical evidence beyond its limits and use it to make grand metaphysical claims. Most of the time, they are smuggling dogmatic metaphysics in under the name of science.

Some of the conditions required for evidence need to be addressed:

1)) Evidence already presupposes a stable subject who can experience, compare and judge it. The recognition of change presupposes continuity. This has been recognised since the Presocratics. To recognise that one state has changed into another, there must be a unified standpoint connecting both states. There needs to be an account of the unity of apperception.

Physicalism has no response to this because it necessarily touches on the metaphysical. Physicalists usually dismiss it as a discussion about the soul without understanding the deeper epistemological point.

2)) You also cannot physically ground causality. This becomes a problem when you claim that all reality is physical while all physical evidence already presupposes causality.

As Hume showed, we never perceive necessary causal connection itself. We perceive one event following another and infer causality. Causality is something physics presupposes, which is fine because physics makes no ontological commitment about what it studies. Physicalism, however, must address it as an epistemological problem.

Physicalism cannot justify why future conditions will resemble present conditions. It therefore cannot justify what makes physical evidence valid in general, let alone use that evidence to justify its worldview. This is a huge problem because physical evidence is meant to explain objective reality, yet the validity of that evidence depends on causality, which is inferred rather than empirically proven.

3)) Mathematics creates the same problem. Science depends on mathematical truths, but mathematical necessity and universality cannot be physically grounded through observation. No finite set of physical observations can establish an infinite or necessary mathematical truth.

Worse, physics presupposes mathematics. To argue that mathematics is physically grounded gets the relationship completely backwards and becomes circular. It would make more sense to adopt a Pythagorean view and argue that reality is inherently mathematical.

Calling mathematics a useful fiction or descriptive language (as many are resorted to do) does not solve the problem. Physicalism still has to explain how a merely contingent physical system can produce mathematical necessity and universality without already presupposing them.

These are not attacks on evidence. They are questions about what must already be true for evidence and science to function at all.

Science can leave these questions open because it remains strictly within the empirical domain and makes no ontological commitment about what it is ultimately studying. It studies relations within phenomena.

Physicalists bypass this limit and make metaphysical claims that they cannot physically justify. These problems therefore fall specifically on them because they are the ones claiming that all reality is physical.

So again, this is not an attack on science. It is an attack on the physicalist claim that reality is fundamentally physical while physicalism remains unable to physically justify the conditions required for physical evidence to be valid.

Neuroscience vs Experience

The same mistake happens with neuroscience.

People act as if brain scans prove that first-person experience is nothing but physical or that it is produced by matter.

Neuroscience is still a science, and just like them studies causal events in space and time. Neural firing is a physical event.

However, first-person experience is prior to third-person science. Practically nobody disagrees that brain states and conscious states are correlated, or that damaging the brain damages experience. But correlation is not identity. It does not prove that matter produces consciousness (especially since physicalism can't justify causality), or that experience is physical.

To use objects of experience to ground or explain the subject of experience is circular because objects are already conditioned by the subject.

Calling the subject an illusion or emergent property does not answer this. An illusion still requires something to which it appears (a subject), while emergence is itself a third-person causal description that already presupposes first-person experience (i.e. temporal sequencing, aka time, which is valid to a subject).

The facts are, making a 3rd-person description of a state/event presupposes first person experience. That doesn't mean everything is therefore first person experience, but it means you have to consider the limits of human cognition (and what it can perceive/abstract) before making grand claims about reality outside the human mind.

The idealist can also argue that spatial objects are representations of inner states or noumenal reality. On that view, the brain is simply how our faculty of knowledge appears in space and time.

Again, I am not disparaging neuroscience or evidence. Neuroscience shows us what the evidence shows. The mistake is treating that evidence as proof of a metaphysical ontology.