Are all theories based on observations?

Question

... or can a theory (like the theory of relativity) be based on pure conjecture?

I was thinking specifically about the General Theory of Relativity which I don't think was confirmed by observation for years after it became a "theory".

Answer 1

Let's start with a partial definition of "theory"

"A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena."

To address your specific example (Einstein's Theories of Relativity), you should understand that indeed these were not pure conjecture. Einstein followed the logic of several important experiments and found them incomplete. The experiments and resulting equations by Lorentz figured prominently in Einstein's deliberations.

In an intuitive step, which perhaps you could call conjecture if you wish, Einstein developed two postulates, and these were concepts upon which he found his theory could be developed. They allowed a logical interpretation for known experimental results of his day, and as such one could say his theories were the result of a process of deduction from there.

It is important to realize that GR and SR are still theories today. While they may be considered "accepted truth", that is not accurate. It is better to say that experimental data has repeatedly verified the predictions of these theories, and therefore "confidence" in their validity is very high. One cannot claim, however, that they are "proven".

I believe Einstein himself said his theories could never be proven, but a single experiment could potentially disprove them.

As I say, confidence in his theories is very high. Probably the most accurate thing one could say is that his theories will be expanded upon as our knowledge grows.

Answer 2

Hypothesis: This is an educated guess based upon observation. It is a rational explanation of a single event or phenomenon based upon what is observed, but which has not been proved. Most hypotheses can be supported or refuted by experimentation or continued observation.

Theory: A theory is more like a scientific law than a hypothesis. A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers. One scientist cannot create a theory; he can only create a hypothesis.

In general, both a scientific theory and a scientific law are accepted to be true by the scientific community as a whole. Both are used to make predictions of events. Both are used to advance technology.

The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law governs a single action, whereas a theory explains a whole series of related phenomena.

An analogy can be made using a slingshot and an automobile.

A scientific law is like a slingshot. A slingshot has but one moving part--the rubber band. If you put a rock in it and draw it back, the rock will fly out at a predictable speed, depending upon the distance the band is drawn back.

An automobile has many moving parts, all working in unison to perform the chore of transporting someone from one point to another point. An automobile is a complex piece of machinery. Sometimes, improvements are made to one or more component parts. A new set of spark plugs that are composed of a better alloy that can withstand heat better, for example, might replace the existing set. But the function of the automobile as a whole remains unchanged.

A theory is like the automobile. Components of it can be changed or improved upon, without changing the overall truth of the theory as a whole.

Answer 3

No, not all theories are based on observations. Einstein's theory of General Relativity was developed purely based on Einstein's ideas on physical principles (the equivalence principle) and mathematical elegance. So in this case, it is based purely on conjecture (but the conjecture is guided by logical reasoning). However, many observations later provided significant evidence to support the validity of General Relativity.

Similarly, Superstring Theory is another example of a theory based purely on physical principles and mathematical consistency. There are NO observations for which Superstring Theory derived its assumptions, nor observations to support the conclusions of the theory (at least for now).

Answer 4

A theory can be based on pure conjecture. In order to be a scientific theory, the theory must be refutable: it must be possible to demonstrate by some means (such as by observation) that it is not true. The reason for this is that it can be shown that the predictive power of any theory derives exclusively from its refutability: if the theory is not refutable, it can predict nothing. The theory of relativity predicted a number of effects, which were observed in practice, especially in Hiroshima and Nagasaki.

Answer 5

To be true to the "scientific method", GR would have had to predict an observation that had never been made before that could not be explained by the prevailing relevant theory (Newtonian mechanics, in this case) to graduate from "hypothesis" to "theory". Explaining a past observation that could not be explained before (called a retrodiction) often brings charges that theory may have been contrived to do just that, so is considered a weaker test. I believe the first test was a retrodicition of the (pior) observation of the precession of Mercury's orbit. It's possible that some slack was cut since the expanation was so eloquent that it left little room for contrivance. Personally, though, i would have held out for the deflection of star light passing near the sun (a true prediction) before calling it a theory. I'll bet a lot of others did to, but I'd have to check my history book.

Answer 6

Einstein's special theory of relativity was based on observation: the failure of the Michaelson-Morley experiment to detect the so-called "ether wind" (it wasn't detected because it doesn't exist). His general theory of relativity was based more on conjecture, but has since explained many observations that could not be explained otherwise (bending of starlight near the sun, precession of Mercury's orbit, etc.)

Answer 7

A theory is only a hypothesis until it is tested. It can be formed by mathematics or direct observation, but is only a theory after test in the real world. mathematical proof is not acceptable to a physist

Answer 8

You are correct. A theory does not have to be based on empirical evidence to be a theory. It does not even have to be based on empirical evidence to be a widely accepted theory.

(see String theory)


... don't get stuck on definitions of the word theory, that is an english problem ...

Answer 9

As any submit-Positivist actuality seeker of technological know-how will inform you, ALL remark is concept-laden. there is not any "immaculate concept". this is why experiments attempt hypotheses. No scientist is going out and "basically seems": there is often some theoretical context for the remark. That stated, interior the Social "Sciences", there are fewer exams in this, there are fewer constraints, and there are fewer stable observations frequently. and of direction, there's a extra physically powerful temptation to make the main this - intentionally or inadvertently - to make an ideological factor. (And there are examples of this on all sides: Evolutionary psychology has a particularly anti-feminist bias and Sociology has a reasonably feminist bias.) in spite of the fact that, it rather is going to likely be stated that lots feminist concept isn't - nor does it purport to be - scientific concept. extremely, it may provide interpretative schema, frameworks for describing social and cultural phenomena. And as such, their use in offering observations isn't beside the point. (nonetheless one might locate the frameworks simplistic.)

Answer 10

theories are based on hypothesis that have been tested. a theory cannot be based on conjecture because that is not what a theory is.