Theory....
rules and techniques: the body of rules, ideas, principles, and techniques that applies to a subject, especially when seen as distinct from actual practice.
speculation: abstract thought or contemplation.
idea formed by speculation: an idea of or belief about something arrived at through speculation or conjecture.
(someone asked me to have a look.....this is what I found)
(hope he is reading this)
Humans usually apply fallacious concepts without their own awareness.
Science usually goes through 3 stages to determine a scientific truth,
1) observation
Science is basically dealing with a set of rules behind a repeating pattern. Observation is achievable basically because the pattern itself can be repeated infinitively. Say, you can observe how the earth revolving around the sun because the number of times the earth revolving the sun is infinitive.
2) formulation
Through the possibly infinitive observations, you can develop theories about how it repeats. You can then try to quantitatively describe how it repeats, say, using a formula.
3) prediction
This is to put your quantitative descriptions (formulated rules) into tests. If they predict correctly, the set of rules discovered/formulated by you is considered a truth (a formal scientific truth). If the prediction fails or fails to be within an acceptable variance (say, due to equipment capability limit), the set of rules you developed is considered falsified.
To simply put a set of rules behind a repeating pattern is considered "proven" when the prediction of the pattern using this set of rules doesn't fail.
For an example, water dissolves into hydrogen and oxygen. This holds true no matter what. That is, you make a prediction (that water must dissolve into H2 and O2) before each and every experiment and that your prediction will never fail. You deserve a Nobel Prize shall your this prediction actually fails.
A human brain thus realize/recognize that it is a truth as predictions never fails.
This is the nature (predictability and falsifiability) of what science is.