"Only I must observe, that the vulgar conceive those quantities under no other notions but from the relation they bear to perceptible objects. And it will be convenient to distinguish them into absolute and relative, true and apparent, mathematical and common. ... instead of absolute places and motions, we use relative ones; and that without any inconvenience in common affairs; but in philosophical discussions, we ought to step back from our senses, and consider things themselves, distinct from what are only perceptible measures of them".

ChatGPT said:

This passage is from Isaac Newton's Scholium to the Definitions in the Principia Mathematica. In it, Newton distinguishes between absolute and relative quantities—particularly space, time, place, and motion.

Here’s a brief unpacking of the key ideas:

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1. Distinction Between Absolute and Relative Quantities:

• Absolute quantities are inherent and independent of perception or external reference. For instance:

  • Absolute time "flows equably without relation to anything external."

  • Absolute space remains "always similar and immovable."

• Relative quantities are those we actually observe and measure, based on the relations between objects:

  • Relative time is measured by motion (e.g., clocks).

  • Relative space is determined by the position of things relative to each other (e.g., distance between two objects).

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2. "The vulgar conceive...":

Newton criticizes the common (or vulgar) conception of these quantities, which is tied to sensory experience. The “vulgar” confuse relative with absolute because they rely entirely on perceptible measures. Newton sees this as a philosophical error.

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3. Usefulness in Common vs. Philosophical Contexts:

• In common life, relative measures are sufficient and practical.

• In philosophy (i.e., natural philosophy—science), Newton argues we must "step back from our senses" and consider the deeper, unobservable realities—the absolutes—which underlie our measurements.

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Philosophical Stakes:

This is a foundational move in modern physics. Newton is asserting the existence of an objective reality, independent of human perception, which must be described through abstract reasoning—not merely by sense data. This stance stands in contrast to empiricist or phenomenalist positions, which might argue that only relations or perceptions are knowable.

It's also interesting in light of later developments, such as:

• Mach’s principle, which critiques Newton's absolutes.

• Einstein's relativity, which redefines space and time as interdependent and relative to the observer—effectively rejecting Newton’s absolutes.

Would you like a rephrased or interpretive version of this passage in contemporary language?

You said:

Yes

ChatGPT said:

Certainly. Here's a contemporary rephrasing of Newton's passage, maintaining the philosophical nuance:

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“Ordinary people tend to think of quantities like space and motion only in terms of how they relate to things they can perceive with their senses. But it's useful to distinguish between different kinds of these quantities—some are absolute and true, while others are relative and apparent, some are mathematical, others more commonly understood.

In daily life, we rely on relative positions and motions—what we can see and measure—and that usually works just fine. But when we're trying to understand the nature of things more deeply, in philosophical or scientific inquiry, we need to look beyond what our senses tell us. We have to separate the actual things themselves from the shifting appearances we measure them by.”

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This reframing highlights Newton’s core insight: that science must abstract from appearances in order to understand underlying reality. It’s a metaphysical claim about the difference between what is and what merely appears—a distinction that haunted philosophy before and after Newton.