From How Science Works:
The process of science is the opposite of “cookbook.” In contrast to the linear steps of the simplified scientific method, this process is non-linear.
The process of science is iterative. Science circles back on itself so that useful ideas are built upon and used to learn even more about the natural world. This often means that successive investigations of a topic lead back to the same question, but at deeper and deeper levels.
The process of science is not predetermined. Any point in the process leads to many possible next steps, and where that next step leads could be a surprise.
The simplified, linear description of the scientific method implies that science concludes … but in reality, scientific conclusions are always revisable if warranted by the evidence. Scientific investigations are often ongoing, raising new questions even as old ones are answered.
Scientific testing is at the heart of the process. In science, all ideas are tested with evidence.
The early stages of a scientific investigation often rely on making observations, asking questions, and initial experimentation — essentially poking around.
Science is a process, but one that relies on accumulated knowledge to move forward.
A scientific state of mind digs deeper (paraphrase).
Scientific knowledge is built as people come up with hypotheses and theories, repeatedly test them against observations of the natural world, and continue to refine those explanations based on new ideas and observations.
Scientists strive to evaluate their hypotheses from all angles, seeking out both supporting and refuting evidence.
There are multiple lines-of-evidence and many criteria to consider in evaluating an idea.
An experiment is a test that involves manipulating some factor in a system in order to see how that affects the outcome. Ideally, experiments also involve controlling as many other factors as possible in order to isolate the cause of the experimental results.
The real world is messy and complex, and often, interpreting the evidence relating to an idea is not so clear-cut. To complicate things further, we often have to weigh multiple lines of evidence that are all relevant to the validity of a particular idea.
Data become evidence only when they have been interpreted…the same data may be interpreted in different ways…However, this does not mean that interpretations of evidence are simply opinions.
Evaluating an idea in science is not always a matter of one key experiment and a definitive result. Scientists often consider multiple ideas at once and test those ideas in many different ways. This process generates multiple lines of evidence relevant to each idea.
The evaluation of scientific ideas is provisional. Science is always willing to resurrect or reconsider an idea if warranted by new evidence.
What happens when science can’t immediately produce the evidence relevant to an idea? Absence of evidence isn’t evidence of absence. Science doesn’t reject an idea just because the relevant evidence isn’t readily available.
Sometimes the available evidence supports several different hypotheses or theories equally well. In those cases, science often applies other criteria to evaluate the explanations. These are more like rules of thumb than firm standards.
Rule of thumb: all else being equal, scientists are more likely to put their trust in ideas that generate more specific expectations (i.e., are more testable)… [and] are more parsimonious.
The principle of parsimony suggests that when two explanations fit the observations equally well, a simpler explanation should be preferred over a more convoluted and complex explanation.
All scientific tests involve making assumptions … but most of these are assumptions that can and have been verified separately.
In terms of the process of science, members of the community play several essential and direct roles: fact checker/critic, innovator/visionary and cheerleader/taskmaster.
Scientists aim for their studies’ findings to be replicable — so that, [an experiment should yield the same results when repeated by different researchers].
The desire for replicability is part of the reason that scientific papers almost always include a methods section, which describes exactly how the researchers performed the study.
Occasionally, scientific ideas (such as biological evolution) are written off with the putdown “it’s just a theory.” This slur is misleading and conflates two separate meanings of the word theory: In common usage, the word theory means just a hunch, but in science, a theory is a powerful explanation for a broad set of observations.
To be accepted by the scientific community, a theory (in the scientific sense of the word) must be strongly supported by many different lines of evidence.
Accepted theories are the best explanations available so far for how the world works. They have been thoroughly tested, are supported by multiple lines of evidence, and have proved useful in generating explanations and opening up new areas for research. However, science is always a work in progress, and even theories change.
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Note: Unless otherwise indicated, these are excerpts from How Science Works. However, I did make some changes to punctuation (e.g., capitalizing the first word) and left out some words for sake of clarity and readability. The original text is much more detailed and provides numerous examples - highly recommended.
Reference: How Science Works - Understanding Science. 2022. University of California Museum of Paleontology. 3 January 2022 http://www.understandingscience.org