QuestionsCan science explain everything?Physical science left the mind out: it cannot explain everything
Can science explain everything?True, but not everything

Physical science left the mind out: it cannot explain everything

Mind and Cosmos (Nagel)

Thomas Nagel born 1937Consciousness is a subjective point of view that physics does not describe: our idea of nature must be widened.
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What it claims

The current physical conception of nature is incomplete, even as a theory of the physical world, and a complete view will have to include consciousness, reason and values.

Why

Physics was built by setting the mind aside; yet consciousness exists, so its picture of the world is incomplete.

The same idea through history
Thomas Nagel1974In "What Is It Like to Be a Bat?", Nagel shows that consciousness is a subjective point of view that the objective description of physics does not contain. This is the starting point of the wider argument presented here.
Thomas Nagel1986In The View from Nowhere, Nagel studies the tension between the objective point of view "from nowhere" that science seeks and each person's point of view on his own life. He argues there that objectivity cannot say everything about what exists.
Thomas Nagel2012In Mind and Cosmos, Nagel extends the idea: the mind-body problem does not concern only a few animals, it concerns our understanding of the whole cosmos. Consciousness, reason and values are facts that the current physical conception cannot explain, and the complete picture of the world will have to include them.
In short

"Physical science left the mind out: it cannot explain everything" is an argument by Thomas Nagel (The View from Nowhere, 1986; Mind and Cosmos, 2012, 1974) on the question "Can science explain everything?" (answer: true, but not everything). Its claim: The current physical conception of nature is incomplete, even as a theory of the physical world, and a complete view will have to include consciousness, reason and values. According to AskPhilosophy's logic check (Z3 solver), the conclusion does follow from its 3 premises. AskPhilosophy presents 3 objections, 1 of them with a documented reply, and the original text behind each premise, checked word for word.

The View from Nowhere, 1986; Mind and Cosmos, 2012
Valid

Since Galileo, physical science has succeeded by leaving aside what depends on a point of view: colours as we see them, sensations, intentions. It describes a world of masses, forces and distances. Thomas Nagel notes that this choice was a method, not a discovery: it put the mind in brackets to describe the rest better. It would then be surprising if it could explain what it had set aside from the start. In Mind and Cosmos (2012) he concludes that consciousness, rational thought and values are not details that the evolution of bodies will one day explain: a complete view of the world must make room for them, and science may have to change form. Nagel does not propose replacing science with religion or denying present science: he looks for a wider explanation of nature. His book has been much discussed, and often criticised.

P1Modern physical science was built by deliberately leaving out of its description of the world subjective appearances, the human mind, and intentions and purposes.
P2What physics thus set aside is exactly what makes consciousness: adding the brain still leaves out the essential. Likewise, reason (the ability to grasp what is generally true) cannot be explained as a mere extension of consciousness or of instinct.
P3Consciousness, reason and values exist in the world: we are examples of them, and our existence is part of the history of nature.
P4 · implicit premiseA conception of nature that cannot explain facts of nature that exist is incomplete.
So the current physical conception of nature is incomplete, even as a theory of the physical world, and a complete view will have to include consciousness, reason and values.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P4, one could accept P1 to P3 and say that physical science is complete for what it sets out to explain: the rest would be a matter for another description (psychology, philosophy), without nature being "incomplete".
The argument is valid. P1 says physics left the mind out by method. P2 says that, for this reason, it cannot explain it. P3 says the mind exists in the world. With P4, what is missing from the physical explanation is a real gap in our knowledge of nature. The debate is mostly about P2: the step from "present physics does not explain it" to "no physics-like science ever could".
Analogy. A city map that shows only the streets and nothing about the inhabitants can be perfect for getting from one point to another. But it is no surprise that it tells us nothing about what the people who live in the city experience: it was drawn without them.

Objections

3

Each objection is a conversation: click to see who replies and where the debate stands.

Daniel Dennett 1988 · attacks premise 2

What Nagel thinks science leaves out, a private and indescribable "what it is like", is a confused notion. Dennett thinks one should not say "we will explain these qualia" but ask "what qualia?". In his view there is nothing more to explain than what we can discriminate, say and do, and science can study that.

no reply
see the argument
Nagel never answered this objection.
The debate goes on (our summary) Nagel answers, through Mind and Cosmos, that denying what seems obvious amounts to changing the subject; Dennett judges that the obviousness itself is misleading. See Dennett's argument for the details of this debate.
Where the debate stands (our summary)Our summary: a disagreement of substance. For Nagel subjective experience is a real fact that current science does not describe; for Dennett this idea is an illusion of reflection. Neither side has won.
H
H. Allen Orr 2013 · attacks premise 2

Orr, a biologist, judges that Nagel goes from his incredulity ("this seems highly implausible") to the conclusion that Darwinism is false or incomplete, without a real argument. Many scientific truths are counterintuitive, and a scientific education consists in part in distrusting one's intuitions. Orr adds that Nagel is wrong on several points of biology (origin of life, mutations).

Nagel replies
Nagel Nagel (Mind and Cosmos, 2012, introduction; written before Orr's article)
Nagel writes that pointing out the limits of present scientific tools is a task of philosophy, rather than part of the internal pursuit of science. He also says that the target of his book is a speculative world picture built by extrapolation from biology, chemistry and physics, not science itself.
The debate goes on (our summary) Orr accepts that the idea of explanation by purposes (teleology) is not contrary to science in principle, but judges that it lacks evidence and fits biology poorly. Nagel, for his part, offers this "natural teleology" as a hypothesis to explore, without claiming to prove it.
Where the debate stands (our summary)Our summary: most biologists and philosophers of biology judge that Nagel has not shown Darwinism to be insufficient; some philosophers of mind recognise the force of his argument about consciousness. The two questions (Darwinism and consciousness) should be kept apart.
Alex Rosenberg 2011 · attacks premise 3

Rosenberg holds the opposite position: physics, with its laws, says all there is in the world, and what we call "mind", "purpose" or "value" is a useful illusion. He calls this position scientism. For him Nagel's mistake is to take seriously facts (consciousness, values) that science shows to be appearances.

no reply
see the argument
Nagel never answered this objection.
The debate goes on (our summary) Nagel holds, in Mind and Cosmos, that reason cannot be explained as a mere effect of natural selection: if our reasonings were only that, nothing would guarantee that they grasp the truth, including the one that concludes that everything is physical (our summary). We did not find a reply by Rosenberg to this specific objection. The debate is open.
Where the debate stands (our summary)Our summary: an open point. Both authors agree that physics does not describe the subjective point of view; they draw opposite conclusions (science must be widened, or we must give up believing in what it does not describe).
What today's voices say
Defend it
Philip GoffPhysical science succeeded 'because Galileo kicks things off by taking consciousness out of its domain', so it cannot be expected to explain it.