Category:Scientific principles

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Scientific principles


A scientific principle is a statement of "law" that can be used as the foundation for one or more principle-based scientific theories, and which can't normally be broken without invalidating those theories. A principle-based theory has greater scientific credibility than a constructional theory, as it offers more scope for scientific falsifiability.

Types of breakdown

There are three main ways that a principle can "break".

  • It can turn out to be simply wrong. In this case, the principle and any theories based on it, are wrong (such as phlogiston theory, or the miasma theory of disease).
  • It can turn out to be an "engineering approximation". In this case, the principle may still be usable as the basis of convenient approximate short-cut methods, but cannot obviously be used as the foundational basis of further theory.
  • It can turn out to be the limiting case of a larger, more encompassing (and therefore stronger) principle. For instance, the principle of the conservation of energy, and the principle of the conservation of mass were both found to be incomplete in that mass and energy could be interconverted (E=mc²). The two principles could be fused together to create a new principle of the conservation of massenergy.

The third type of breakdown, the absorption of a principle into a larger principle, is considered to be an "honorable death", as it represents a form of scientific progress where a principle "passes the baton" directly to its successor.

General relativity

Einstein's 1916 general theory was designed with the General Principle of Relativity as its foundational principle, and with the assumption that the theory must reduce to special relativity over small regions as a more minor "implementational" principle. When these two principles were found in 1960 to conflict, the 1916 theory failed.

In response, the community downgraded the GPoR within GR to a guideline rather than a principle, allowing special relativity to override the GPoR whenever the two were likely to disagree (Schild 1960). Although the mathematical machinery of the 1916 theory remained, the new "textbook GR" that was taught after 1960 was was no longer technically the same theory, as the rules for how the mathematics were to be applied were now different - where GR1916 had been a principle theory as defined by Einstein, with a high degree of falsifiability, GR1960 was a lower-grade "constructional" theory.

The theorist's method involves his using as his foundation general postulates or "principles" from which he can deduce conclusions ... he must first discover his principles and then draw the conclusions which follow from them. ... The first of these tasks, namely, that of establishing the principles which are to serve as the starting point of his deduction, is of an entirely different nature. Here there is no method capable of being learned and systematicaly applied so that it leads to the goal. The scientist has to worm these general principles out of nature by perceiving in comprehensive complexes of empirical facts certain general features which permit of precise formulation.
— "Albert Einstein, "Principles of Theoretical Physics", 1914    


In an expanding universe, energy is continually lost due to Hubble shift. This suggests that the law of the conservation of massenergy may one day need to be replaced with an even larger law, of the conservation of massenergyspace.