Science Scienti–, sciens (L.) - having knowledge Physical/natural Sciences: Branches of knowledge...

Science

Scienti–, sciens (L.) - having knowledge Physical/natural Sciences:

Branches of knowledge concerned with the matter and functions of the physical universe

Using material evidence from the senses, we create hypotheses about how the material

world works ..

Scientific vs common use ..

Hypothesis: a proposition(s) made as the basis of reasoning .. as a starting point for further investigation (without assuming it is true)

Theory : a system of ideas to explain a phenomenon (eg, ”Darwin/Wallace theory of evolution by means of natural selection).

Fact: taken as true by a community of inquiry (eg, scientists: ”life has evolved”)

”Falsifiability”

Scientific hypotheses / theories / facts must be testable, in order to (in theory) be falsified by material evidence (Kuhn, Popper)

A theory based on good evidence which is not (yet) falsified is accepted ..

We cannot ”prove” theories directly, we can only disprove.

(experimental) evidence tests hypotheses

A good experiment allows you to conclude with some certainty that, on the basis of evidence, you accept or reject the hypothesis.

How can we explain the origin of complex life-forms?

To be acceptable, a scientific explanation must rely on material evidence that supports it; counter-evidence, if such is found, must not falsify the explanation.

* Theory of Creation- Evidence in support?- Evidence against? - How might Creationism be falsified?

* Theory of Evolution

Science can explain complex design

Evolution: process of cumulative change in the heritable characteristics of a population

Evolution

Evidence for evolution

Theories on HOW evolution happens

Evidence for these theories

Evidence for evolution Fossil record. Incomplete, but no evidence found

yet to falsify Affinities (organisms have features in common –

from common ancestry)* Anatomical (eg, limbs)* Biochemical (eg, DNA)* Physiological (eg, body fluids, mitochondria)* Embryological (ontogeny recapitulates ..)

* Geographical distribution of relatives

This bony fish derives from the famous Green River locality in Wyoming, USA, which is a 40 million years old lake (fresh-water).

Jurassic reptile found in South America and Africa (also evidence for Continental Drift theory)

How might evolution happen?

Inheritance of acquired characters: animals respond creatively to their needs. (falsified: DNA makes proteins/bodies, not reverse).

Molecular evolution: much genetic change occurs randomly over time

Natural Selection (Darwin/Wallace)

Theory of Natural Selection(Darwin & Wallace, 1858; Darwin, 1859)

1. Organisms vary, and these variations are inherited (at least, in part) by their offspring.

2. Organisms produce more offspring than can possibly survive.

3. On average, offspring that vary most strongly in directions favoured by the environment will survive.

Are Scientific Facts Discovered?Constructed?

Current perspectives on the philosophy of science reject the idea of an objective base of observations against which our theories can be checked. Instead, the dominant view is that science as public knowledge is not so much a ”discovery” as a carefully checked ”construction”

(R. Driver, Int. J. Sci. Ed.)

Doing science .. making truths

Scientists construct hypotheses, test these through experimentation. If results support hypotheses, papers are presented for peer critique (reviewed) & published (or not), and examined at conferences

Scientific truth: ”What our peers will let us get away with

saying” (Rorty)

(peers: a scientific community)

Do genes or electrons exist?

In our attempts to represent the world, we construct theoretical entities (magnetic fields, genes, electrons) which in turn take on a ’reality’. Rather than viewing observations as the base on which we build our knowledge, these is a sense in which it is our constructions of the world which are ’real’, and it is through these that we interpret and re-interpret our experience.

(R. Driver, Int J. Sci. Ed.)

Disclaimer stickers for science textbooks: 1

This textbook contains material on evolution. Evolution is a theory, not a fact, regarding the origin of living things. This material should be approached with an open mind, studied carefully, and critically considered.

Disclaimer 2

This textbook suggests the earth is spherical. The shape of the earth is a controversial topic, and not all people accept the theory. This material should be approached with an open mind, studied carefully, and critically considered.

Disclaimer 3

This textbook contains material on gravity. Gravity is a theory, not a fact, regarding a force that cannot be directly seen. This material should be approached with an open mind, studied carefully, and critically considered.