physics

Logical determinism

Logical determinism is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Logical determinism rather than just read about it. In short: Logical determinism is the view that a proposition about the future is either necessarily true, or its negation is necessarily true. The argument for this is as follows.

Key takeaways

Logical determinism belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Logical determinism to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Logical determinism from memory before moving on to harder problems.

Reference excerpt

Logical determinism is the view that a proposition about the future is either necessarily true, or its negation is necessarily true. The argument for this is as follows. By excluded middle, the future tense proposition (‘There will be a sea-battle tomorrow’) is either true now, or its negation is true. But what makes it (or its negation) true is the present existence of a state of affairs – a truthmaker. If so, then the future is determined in the sense that the way things are now – namely the state of affairs that makes ‘There will be a sea-battle tomorrow’ or its negation true – determines the way that things will be. Furthermore, if the past is necessary, in the sense that a state of affairs that existed yesterday cannot be altered, then the state of affairs that made the proposition ‘There will be a sea-battle tomorrow’ true cannot be changed, and so the proposition or its negation is necessarily true, and it is either necessarily the case that there will be a sea-battle tomorrow, or necessarily not the case. The term ‘logical determinism’ (Logischer Determinismus) was introduced by Moritz Schlick. Logical determinism seems to present a problem for the conception of free will which requires that different courses of action are possible, for the sea-battle argument suggests that only one course is possible, because necessary. In trying to resolve the problem, the 13th century philosopher Duns Scotus argued in an early work that a future proposition can be understood in two ways: either as signifying something in reality that makes something be true in the future, or simply as signifying that something will be the case. The second sense is weaker in that it does not commit us to any present state of affairs that makes the future proposition true, only a future state of affairs.

See also Master Argument Determinism Free will Problem of future contingents

References Schlick, M. ‘Die Kausalität in der gegenwärtigen Physik’, Naturwissenschaften 19 (1931),145-162; Eng. tr. (by P. Heath, 1979), in Philosophical Papers (Volume II). H. L. Mulder and B. F. van de Velde-Schlick (eds.), Dordrecht: D. Reidel. 176-209 Woleński, J. 'An Analysis of Logical Determinism', 1996.

Notes

Worked examples

Example 1 — a first encounter with Logical determinism

Start with the simplest possible case. Write down what Logical determinism claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Logical determinism before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Logical determinism ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Logical determinism

In research: Logical determinism appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Logical determinism in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Logical determinism is common in secondary-school and first-year university syllabi. It links to neighbouring topics Determinism, Free will, Logic, so understanding it makes those chapters shorter.
In everyday life: Look for Logical determinism outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Logical determinism in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Logical determinism means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Logical determinism out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Logical determinism in simple terms?

Logical determinism is the view that a proposition about the future is either necessarily true, or its negation is necessarily true. The argument for this is as follows.

Why does Logical determinism matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Logical determinism?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Logical determinism.