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Question: How to explain the diversity of living things on earth?
Answer: Assumptions are (almost) everything.
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One explanation is that they were created different.
A second explanation is that there are different forms.
A third explanation is evolution by natural selection.
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The first and third explanations are well known - the second idea (that things are different due to having different intrinsic forms) is a very old one, as still going, but not well known as such.
Well-known exponents of the idea that things differ due to there being different underlying forms include Aristotle, Aquinas, Goethe, D'Arcy Thomson, Conrad Waddington, Steven J Gould (sort of), Stuart Kauffman, Brian Goodwin and Rupert Sheldrake.
In general, these theoreticians tend towards a mathematical - often geometric - understanding of form. This is, indeed, the dominant stream in British theoretical biology (as exemplified by the elite Cambridge-based Theoretical Biology Club).
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How to decide between Creation, Forms and Natural Selection as the cause of the multiplicity of 'species'?
All these can explain enough, in principle 'everything' - so how to choose?
Well, there is really no way of choosing except on the basis of assumptions. Each body of work makes different assumptions.
Creation assumes things like that species were intentionally created with some kind of plan and purpose - however general this plan and purpose might be.
Forms assume that underlying reality is structured, and our job is to discover the identity and nature of these formal structures, and perhaps the mechanisms of how they impose form, or how appearances relate to underlying form.
Natural selection assumes that all significant and lasting variation can be explained by selection processes. In other words, it seeks to explain significant variation using selection processes: undirected variation with replication and competition leading to differential replication.
All three types of explanation find what they look for - and only what they look for.
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So why has Natural Selection carried the day in professional biology? - when results are determined by assumptions, and these assumptions cannot in principle be proven to be more (nor less) true than the rival assumptions?
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The answer is essentially because NS is currently, has led to, and so far proved more amenable to, professional success: to the business of being a professional scientist - getting jobs and funding, researching, teaching and the rest of it.
Professional success may be related to pragmatic or rhetorical usefulness, or it may have nothing to do with such things - after all, ideas of form have considerable prestigious elite influence - for example among mathematicians and computer scientists working in chaos and complexity theory (which are modern variants of ideas of form); and ideas of creation have massive support among religious people.
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And, of course, in general culture the implications of Natural Selection - especially as applied to humans - are accepted and promoted or ignored and suppressed purely according to their political or religious convenience - entirely regardless of reason or evidence.
But within biology as a professional activity there is much more scope deriving from the assumptions of Natural Selection - and that is why it carries the day.
That is the only reason why it carries the day.
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[Note: my main job title is Reader in Evolutionary Psychiatry and I have been reading, publishing and teaching about natural selection for more than 15 years.]
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9 comments:
Thanks for the reference to the British formalists (if they can be called that).
Another line of thought that leads to a similar conclusion can be found in Christopher Alexander, an architect and architectural theorist whose method of design emphasizes living form that emerges through a process of trial and error (a.k.a. variation and selection). His magnum opus The Nature of Order touches briefly on natural phenomena, organisms, and evolutionary theory and emphasizes the need for form as an explanatory principle.
@JK - Thanks - I'll take a look.
One of the signs of our cultural intellectual decline is that people can no longer distinguish between metaphysics and science (perhaps the basis of ancient Greek philosophy).
I mean they cannot distinguish even in principle; never mind in specific instances.
People don't understand what is different between metaphysics and science. I only *got it* a few years ago after reading Ed Feser on Aquinas.
I had, of course, read a lot of such discussion - e.g. David L Hull's Science as a Process, from where I got the basic distinction between the Form and NS traditions, I mention above; and another book by a deep-thinking local Zoologist friend Alec L Panchen - Evolution (Mind Matters) - but I still didn't get it.
Metaphysical assumptions determine what science can find - this is necessarily true, not a matter of opinion!
Science embodies metaphysical assumptions; and Darwinian theory is - of course - not an exception.
But none of the 3 theories you mention are by themselves quite adequate to their explanatory task. To wit:
1. Creation of ... what? Of forms and their instantiations via motions from potentiality to actuality.
2. Forms of ... what? Of actualities that by their motions give rise to novel actualities – that instantiate the forms by actualizing potentialities.
3. Variation & natural selection of ... what? Of forms as expressed in prior actualities.
Forms just sitting there in a Platonic Realm produce nothing. Creation of formlessness is creation of nothing. And selection among entities that have no form and have not been actualized – have not been brought into being – is selection of nothing.
A form that has no concrete being does not exist at all; so that if a form is to operate in the world with _any_ sort of causal effect, it must first be concretely instantiated. That’s the only way it can enter the stream of efficient causes – to produce an effect, you need an effector, which is to say, an actual entity: a form that has been materialized – i.e., moved from potential existence to actual existence – for a reason.
The reason things happen is yet a fourth aspect of their causation. The four aspects are:
1. Material – the data for the operation of selection are the actualized forms of the past.
2. Efficient – the act of selection is an act of creation; it is the motion from potentiality to actuality.
3. Formal – selection chooses to enact or embody a form.
4. Final – the reason a form is selected is that it is understood as Good, mutatis mutandis.
Note that the procedure as so far described says nothing about the agent of the motion from potentiality to actuality, that involves all four sorts of causes; it says nothing about the effector, or the set of effectors (as in additive vectors). Is the effector set God, or creatures, or a combination of the two? If the effector set is wholly God, then creatures have no effective existence, which contradicts the most basic factor of all our experience (i.e., that we do really exist, that the qualia of our experience are qualities of some actual thing). If the effector set is wholly comprised of creatures – which is to say, of contingent beings that themselves were caused – then, because contingent agency cannot enact itself (a creature that does not exist to have creative power in the first place cannot act to bring itself into being so as to be able to possess creative power), their creaturely existence and capacity to act must be then be in the first place the product of the creative activity of God. So we arrive at the conclusion that the agency by which the four sorts of causes above all operate to move a form from potentiality to actuality derives primarily from God, and secondarily from creatures.
There is another way of choosing, in addition to the ways mentioned.
By observation, using the formula of: It is what it is.
Forms are different because they have different tasks to perform. Differing niches into which they fit.
Why is a bee shaped like a bee?
Because it must be, in order to fit a flower and collect its pollen. A zebra would not suffice.
Why is a human shaped like a human?
So it can wreck things as efficiently as possible.
A mosquito would not suffice.
I think I am just repeating Kristor, but it seems to me that all three are probably true but address different questions (formal vs efficient causes, etc). Evolutionary biologists certainly concentrate on natural selection, but it seems to me that every other branch of biology is concerned with form and function.
@Kristor and @Bonald - I grappled with the Thomistic system in relation to biology - for example in the very good work of David Oderberg
http://www.reading.ac.uk/philosophy/
about/staff/d-s-oderberg.aspx
In principle the theory of Natural Selection could be pursued in isolation from metaphysics, if it was embedded in a larger awareness against which it could periodically be checked - but this seems to go against human nature - people pick up a partial idea and run with it.
When your only tool is a hammer, everything looks like a nail.
And the same applies to Thomistic philosophy itself - it is partial, distorted - and its practitioners ran away with it, let it run away with them.
Another Christopher Alexander fan here. However, his conception is not much different than the Platonic ideal, if at all.
In the Platonic ideal, forms exist because of the logical opportunity created by the interaction of other forces. Those forces also exist as forms, so what we see in the physical world is the EFFECT of forms, which are its CAUSE. All else are proximate causes, e.g. not essential.
Natural selection advanced -- in my view -- because it made more sense than the previous views. It in turn needs elaboration. Clearly a sculptor who simply cut away the unfit would produce only yeast; some other motivic force, an expansive force, exists to counter the cutting-away.
None of this touches the idea that forms, whether generative or static, exist outside of the material itself. They are logical constraints on matter, time, space, etc.
Given the theory of relativity, this makes perfect sense, as materiality (incl. energy) could not arise without a precursor or enclosing state.
It's interesting to speculate what a clear philosophical articulation of Alexander's views would look like.
It seems clear that he has more of a Platonist streak than people do who talk about "emergence" as an explanation for properties of physical systems that seem quite different from the properties of their components. There seems to be a sense of a spark from above, of an attraction exerted by a form as it gradually comes into focus and becomes realized.
On the other hand it seems unlikely that an artist who likes working with materials and is conscious of particularities of setting and idiosyncracies of purpose and personality would be altogether a Platonist. Maybe more of an Aristotelian, who thinks that forms depend on the particulars that instantiate them?
I'm an Alexander fan, too. I have not thought too much about how to present his thought in a systematic way. Ditto for Sheldrake. They seem like hands on guys, both of them - natural historians rather than abstract theoreticians. They find the forms active in nature, and report their findings without a lot of metaphysical interpretation.
I think Brett is right that the forms assert themselves logically. When you are building something, the logic of the project and its factors stringently constrains the space of potentially workable solutions. Liebniz would have called it the logic of compossibility: factors can come together in only relatively few configurations that will succeed in meeting your design objective.
@ bgc re Thomism: I'm not hung up on Thomas - I'm actually more of a Whiteheadian than a Thomist (their metaphysical systems map to each other quite tidily, I find) - it's just that I'm flat unable to think of a sort of cause that is needful for adequacy, outside the Aristotelian 4, and I can't arrive at a feeling of adequacy with anything less.
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