The argument stated at its strongest
The argument under examination is aimed at a familiar theistic claim often called the principle of proportionate causality. In careful Aristotelian-scholastic versions, the claim is not merely that a cause must contain a miniature copy of its effect; it is that an effect requires an adequate causal ground, and that whatever is in the effect must be present in the cause formally, virtually, or eminently. In popular apologetic form, however, this is often compressed into a simpler slogan: life cannot come from non-life, consciousness cannot come from unconscious matter, rationality cannot come from irrational particles. Therefore, if life, mind, and reason exist, their ultimate source must be adequate to life, mind, and reason.
The naturalist reply is that this principle, if read as literal property-copying, is false. The world is full of cases in which wholes display properties that their components do not display individually. Isolated hydrogen and oxygen atoms, and even isolated water molecules, are not wet; bulk water under suitable conditions has liquidity and wetting behaviour. A single molecule does not have a temperature in the ordinary thermodynamic sense; an equilibrium or near-equilibrium collection can. Carbon, hydrogen, oxygen, nitrogen, and other elements are not alive, but some highly organised chemical systems are. A single neuron is not conscious, but a naturalist may argue that a suitably organised brain is. The broad thought is associated with J. S. Mill's discussion of "heteropathic" effects, C. D. Broad's emergentism, Philip Anderson's slogan "more is different," and more recent work by philosophers such as Mark Bedau, Timothy O'Connor, and David Chalmers. These writers disagree sharply: Bedau is known for "weak emergence," O'Connor has defended stronger emergent causal powers, and Chalmers treats consciousness as a case where ordinary reductive explanation faces special difficulty.
On this view, emergence is not magic. It is the appearance of system-level properties when parts are arranged in the right way and interact under the right laws. Liquidity is not imported from a prior liquid substance; it arises from molecular structure and interaction. Self-replication is not possessed by isolated atoms; it may arise in complex chemical networks. Biological life, on many naturalistic accounts, is not a separate ingredient added to matter but a stable, self-maintaining, metabolising, reproducing organisation of matter. Consciousness is more controversial, but the naturalist says there is no demonstrated a priori impossibility in its arising from sufficiently organised nervous systems.
The strongest version of the argument is therefore modest. It does not claim that abiogenesis has been fully solved, or that consciousness has been reductively explained. It claims that the principle "a cause cannot give what it lacks" cannot be used as an a priori veto against such explanations. The existence of emergent properties shows that new properties can belong to wholes even when they do not belong to the parts taken separately. So, the naturalist concludes, proportionate causality is not an evident law of reason. It is at best a metaphysical thesis needing defence, not a rule that can simply be invoked to rule out life from non-life or mind from matter.
Where the naturalist argument succeeds
This critique has real force against crude versions of the theistic argument. If someone says that an effect must resemble its cause by possessing the same property in the same way, the claim is plainly false. A spark can cause an explosion without itself being an explosion. Non-red objects can cause a red image on a screen. Non-wet molecules can compose a wet liquid. Non-living atoms can compose a living cell, if the right organisation exists. The world does not work by simple property copying.
It is also correct that "life cannot come from non-life" is often stated as though it were a scientific law. It is not. Biology does not contain a principle saying that life can arise only from pre-existing life under all possible conditions. The historical claim that life on Earth arose from earlier life is different from the origin question. Abiogenesis research remains incomplete, but incompleteness is not impossibility. Serious theists should not treat open scientific questions as though they had already been settled in their favour.
The same caution applies to mind. Neuroscience has established deep dependencies between mental life and brain activity. Damage the brain, and memory, perception, language, personality, and agency can be altered or destroyed. That does not by itself prove reductive physicalism, but it makes any account of mind that ignores the brain scientifically unserious. A naturalist is entitled to say that conscious minds, if they are wholly dependent on organised brains, would be another example of system-level reality rather than a violation of causality.
So the naturalist argument establishes at least this: a simplistic principle that causes must already possess their effects formally, in the same mode, is false. Emergence is enough to defeat that version.
The strongest theistic reply
The stronger theistic reply is that this attacks a weakened version of proportionate causality. In the Aristotelian and scholastic tradition, the claim is not usually that a cause must possess the effect in the same way the effect possesses it. Rather, the cause must contain the effect formally, virtually, or eminently. The terminology is old, but the distinction matters.
- Formally: the cause has the feature in the same way the effect has it, as when fire causes fire.
- Virtually: the cause has a power sufficient to produce the feature without itself displaying it in the same form, as when chemical and physical powers produce liquidity.
- Eminently: the cause has the relevant perfection in a higher mode, a notion used in classical theism.
Once the principle is formulated this way, ordinary emergence does not refute it. Liquidity emerging from molecular organisation does not show that liquidity came from nothing, or from causes with no relevant capacities. It shows that molecular powers, spatial relations, and environmental conditions can be sufficient for bulk liquid behaviour. Temperature likewise is not present in each molecule as a tiny private temperature; in thermodynamics it is a macroscopic state parameter, and in statistical mechanics it is grounded in the distribution of microstates, with average kinetic energy giving a simple approximation in cases such as ideal gases. These are not counterexamples to proportionate causality understood virtually. They are examples of it.
This reply is important because many naturalist examples prove less than they appear to prove. They show that wholes can have properties their parts lack individually. They do not show that effects can arise without any adequate causal basis. The real dispute is not whether higher-level properties can emerge. Nearly everyone can accept that in some sense. The dispute is whether life and consciousness are like liquidity and temperature: fully explicable in terms of the powers, structures, and relations of their material basis.
For life, the naturalist has a plausible research programme. Living organisms are extraordinarily complex, but metabolism, replication, heredity, membranes, and selection are not obviously beyond chemistry. Origin-of-life research has not produced a complete pathway from prebiotic chemistry to the first living systems, but the category of life does look increasingly organisational rather than a separate substance or force. Here the proportionate-causality objection, by itself, seems weak. It cannot simply declare abiogenesis impossible.
Consciousness is harder. Many philosophers of mind, including David Chalmers, have argued that subjective experience presents a "hard problem" not captured by functional or behavioural description. Jaegwon Kim pressed a different but related problem for non-reductive physicalism: if mental properties are genuinely novel and causally efficacious, how do they avoid either being reducible to physical causes or competing with them? This is the causal exclusion problem. If physical causes are already sufficient for physical effects, what causal work is left for emergent mental properties?
This creates a dilemma for some naturalist uses of emergence. If emergence is weak, meaning that higher-level properties are fully dependent on and explainable by lower-level physical organisation, then the naturalist owes an account of how subjective experience fits into that structure. If emergence is strong, meaning that genuinely new causal powers arise which are not reducible to physics, then the view may no longer look like standard physicalism. It may become a form of emergentism that accepts basic psychophysical laws or novel ontological features. That is not theism, but it is also not the simple picture of matter alone doing all the explanatory work in a familiar sense.
The best naturalist reply
The naturalist can reply that this is not a defeat but a clarification. First, proportionate causality in its more flexible form may be true but nearly empty. If "the cause has the effect virtually" means only "the cause has whatever powers are sufficient to produce the effect," then no naturalist need deny it. Matter organised in the right way would have consciousness virtually, if consciousness in fact arises from such organisation. The principle would not rule out emergence; it would merely redescribe successful emergence after the fact.
Second, the naturalist can insist that difficult explanatory gaps are not a priori barriers. The history of science contains many cases where phenomena once thought irreducible were later integrated into broader theories. This does not prove that consciousness will be explained physically, but it justifies caution about declaring it impossible. Daniel Dennett and Patricia Churchland, for example, have argued in different ways that the mystery surrounding consciousness may be reduced by better accounts of cognition, representation, attention, and self-modeling. Illusionists such as Keith Frankish go further, arguing that some of our intuitions about phenomenal consciousness are themselves misleading.
Third, the atheist or non-theist may accept non-reductive views without embarrassment, though this may require a broader understanding of "naturalism" than strict reductive physicalism. Some philosophers defend property dualism, panpsychism, neutral monism, or strong emergentism; others, such as Dennett and the Churchlands, reject those moves and remain more firmly physicalist. The important point is that these non-reductive options are not automatically theistic if they do not appeal to a divine mind or purpose. So even if consciousness is not reducible to current physics, that alone does not establish theism.
These replies succeed in limiting what the theist can claim. The naturalist is right that unsolved problems in abiogenesis or consciousness do not license a leap to God. The burden remains on any theistic argument to show not merely that naturalism has difficulties, but that theism explains the relevant facts better and without equal or greater costs.
What the argument establishes
The emergence argument establishes something significant but limited. It defeats a crude version of proportionate causality according to which causes must possess effects in the same form. It also blocks an easy dismissal of abiogenesis and physical accounts of mind. At minimum, higher-level properties and patterns are indispensable in successful scientific explanations, and no serious discussion should pretend that novelty at the level of wholes is impossible in principle.
But the argument does not, by itself, refute every serious version of proportionate causality. Properly stated, that principle need not deny emergence. It can say that emergent properties must be grounded in the powers and organisation of what gives rise to them. Liquidity and temperature fit that requirement very well. Life may fit it too, though the historical pathway remains an open scientific question. Consciousness remains the most difficult case, because it is disputed whether subjective experience can be treated like other system-level properties.
Nor does the critique establish theism. Showing that consciousness is hard for physicalism would not show that a divine mind exists. Showing that abiogenesis is incomplete would not show that life was supernaturally produced. Internal critique is not a shortcut to a positive worldview.
The fairest conclusion is this: emergence prevents theistic arguments from using proportionate causality as a simple knockdown argument against life from non-life or mind from matter. However, emergence also should not be used as a magic word that dissolves all explanatory burdens. For life, the naturalist programme is scientifically serious and may succeed. For consciousness, the question remains philosophically unsettled. The debate turns not on whether new properties can emerge, but on whether the particular novelties of life and mind can be adequately grounded in the material causes proposed for them.