Thread: Theory

On page 9, 2nd paragraph of of A Brief History in Time, Hawking says that theory only exists in the mind and has no other reality (whatever that may mean.)

I would like to discuss the implications of this and how it might affect the objectivity of science.

I say it doesn't affect it at all to be honest. Just because Hawking says it does not mean it has actual real world implications.

Originally Posted by jjg

On page 9, 2nd paragraph of of A Brief History in Time, Hawking says that theory only exists in the mind and has no other reality (whatever that may mean.)

That seems reasonable to me. A theory is a concept, an idea. It can only exist in the mind (or on paper waiting to be transferred to another mind).

I would like to discuss the implications of this and how it might affect the objectivity of science.

Well, it means we can't do science by putting two theories on the scales and seeing which one weighs more. But apart from that...

If I may, it could have been his ambition.

I don't know it just smells like Kant's noumenon/phenomenon. The part that bothers me is "it has not other reality (whatever that may mean." Is Hawking saying that what we subjectively conceive does not compliment objective reality?

Originally Posted by jjg

I don't know it just smells like Kant's noumenon/phenomenon. The part that bothers me is "it has not other reality (whatever that may mean." Is Hawking saying that what we subjectively conceive does not compliment objective reality?

Not at all. Just that a theory is a description of the reality we perceive. (What relationship that has to any external reality or whether such a reality exists is another question - and one I am not terribly interested in).

If I were to give you a description of the room I am in, that description does not have any physical reality outside of our minds. From that description you will have an idea of the room I am in, but you won't have the room.

I'm just thinking he was taking a go at being the mind of Everything in the event he found the theory of all things.

A theory in science is a model. It bears the same relationship to the thing it purports to explain as a set of plans do to a finished building. Theories may be strong or weak depending on the weight of evidence to support them. A very strong theory can be said (in unscientific terms) to explain what it sets out to explain in a way that is very probably correct.

For example : The theory of biological evolution is a model of how life changes over time. It is a very strong model, since there is a vast amount of evidence to support it. A scientist would not say it is very probably correct, but that is what 'very strong model' means to a non scientist.

The theory, however, is not the reality. It merely represents the reality, and so it exists, as Hawking said, only in the mind.

Yep. Evolution (the "thing") happens. The theory of evolution describes how it happens (at our current best level of understanding).

A theory is a mental construct.

In logic and maths, a theory is a set of sentences (statements), with well-defined logical relations defined on that set.

A scientific theory is a theory which claims to describe in some way a part of reality (the physical world).

In maths and logic the terms 'theory' and 'model' have distinct meanings.

In science they may well have the same meaning.
Example: 'The Copernican theory of the solar system', 'The Copernican model of the solar system'.

The important features/properties which a theory should/may possess are these:
1. Consistency
2. Soundness
3. Completeness
4. Utility (e.g. explanation, prediction).

In logic and maths these can be precisely defined.

In science, a theory should/may also have empirical support, confirmability, testability, falsifiability.

Elterish

Hope you are not getting confused between hypothesis and theory.

In science, a theory has to have empirical backing. An idea without such backing is a mere hypothesis. The hypothesis has to generate testable predictions, and be so tested many times, without falsification happening, before it can be called a theory.

Of course, the word 'theory' has a much looser definition in everyday, non scientific use.

Mind you, such words can be misused by scientists, also. Like the phrase "string theory". It should be "string hypothesis" since these ideas have not yet been empirically tested.

I would go further and say that even a hypothesis should have some evidence. Otherwise it just speculation (which may lead to a hypothesis).

A hypothesis is a statement whose logical form is hypothetical (also called conditional or implicational).

Sometimes this form is not immediately apparent.

Example the well known saying: 'Red sky at night, shepherds delight' is a hypothesis for it can be
re-expressed to exhibit its logical form as: 'If there is a red sky at night, then the shepherds will be delighted'

A hypothesis is a much simpler concept than the concept of theory.

A large part of what scientists do is 'hypothetical' (supposition, conjecture) as it's a 'hypothetico-deductive' process.
They start with the hypothesis (hypotheses), then perform deductions from those statements.

Example: Let us suppose that the velocity of light is a constant, then (with the principle of relativity), I can prove that E = mc² .