The proposition denoted by the English statement "only matter exists" has a truth value that's constant in time. I want to know if it's true.

To answer the question, you need to know the meanings of the words 'only", and 'exists'. The term 'matter' must be ostensively defined. To communicate the term to a child just learning to speak, touch a bunch of objects in succession and utter 'matter' each time.

"Only matter exists" means

∃ x[x exists] ∧ ∀ x[x exists → x is matter]

Then for the meaning of existence, I offer the following definition:


x exists if and only if x is in the current moment in time.

My father died, so he's no longer in the current moment in time, so he doesn't exist.

  • 3
    You have been told before that this is not a site for you to push your personal philosophies. Commented May 6 at 22:07
  • 4
    Wouldn't it be wonderful if to answer questions we only needed to know the meanings of the words in them. Then dictionaries could replace all those microscopes and telescopes.
    – Conifold
    Commented May 6 at 22:53
  • Any string of characters could be said to be true, with the right definitions. But normally, we say that photons (for example) are not matter, as they are massless and not arranged into atoms.
    – causative
    Commented May 7 at 1:29
  • How could we possibly, even in principle attempt to answer this question? To say something is all that exists, we must be aware of everything that exists. Inside black holes and beyond the observable universe, and before the big bang.... how are we supposed to say what exists in these remote time/places? Commented May 7 at 3:41
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    In logic, 'exists' is conventionally used in a timeless fashion. So, Albert Einstein exists but he is not alive at the time of my writing this comment. However, if you are asking in a roundabout fashion whether physicalism is true, that is a subject on which there is much debate. There is an SEP article on it.
    – Bumble
    Commented May 7 at 4:00

6 Answers 6


It is a false proposition.

"To exist" means the same as "to be observable". All matter is observable, but also ideas, emotions, memories and knowledge are observable things.

They are directly observable to the person who holds them and as they have an effect on the person's behaviour, they are indirectly observable to others, too.

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    Do you have a source for claiming "To exist" meaning the same as "to be observable"? Furthermore, what does "observable" mean? It is an even unclearer definition than "to exist".
    – Tvde1
    Commented May 7 at 11:56

The proposition is so clearly and trivially wrong that I wonder whether there is a deeper meaning or agenda here that I'm just not understanding.

  • Matter (in the form of the 17 fundamental particles) exists.
  • The fundamental forces (electromagnetic, strong, weak, gravitational) exist.

This would make up the meaning of "existence" in purely physical terms, and here already, at the very least energy is also included in stuff that exists. Since Einstein we know that matter and energy are equivalent; and at the very least since the Standard Model was established it is clear that matter without energy (i.e. without the 3 fundamental forces except gravity) is not a concept worth thinking about. Atoms only exist because of the strong and weak interaction; and matter as we know it in everyday terms is completely unthinkable without the electromagnetic force.

Speaking purely physically/scientifically, there exists nothing more, as far as we know today. Absolutely every single aspect of reality that is accessible to physics/science eventually boils down to that.

From a philosophical viewpoint, you can then argue whether you want to enlarge the term "existence" to further aspects, for example, roughly ordered from physical to more non-physical:

  • structure (i.e. how the matter is put together to carry information, for example)
  • thoughts (the actual thoughts we observe in our head)
  • ideas (things we could write down, including fantastical inventions clearly not compatible with the universe as we know it)
  • abstract concepts (maths etc.)

And probably quite a few things I'm not thinking about now. At this point we are not so much talking about these bullet-points, but about the literal definition of the word "existence", and as you can guess, there are philosophical streams that accept or denie the existence of all the examples in some form or fashion.

So even a straight physicalist would not be saying that only matter exists.


Matter is a highfalutin abstraction supposedly comprising the substratum "stuff" of the world. But we do not encounter matter eo ipso. We experience perceptible shapes, forms, and events. While continuing his theme "we have never been modern," Bruno Latour writes of "the not-so-very material MATTER, 'idealism of materialism' of the Moderns. In turning toward the craftsmen, the ingenious engineers who actually build engines and machines…." it scarcely serves any purpose (see Inquiry into the Modes of Existence, 2013, 98, 209).

Matter has always been linked to a political idea, as the first science studies saw, especially all that plays out around the idea of ​​a passive mechanical matter entirely subject to a mechanical God, devoid of the least autonomy in the least of its workings and which avoids absolutely the possible "uprising" of the "masses", whether they be stones, plants, animals or republicans.

For more on this see, Shapin, Steven, and Simon Schaffer. Le Léviathan et la pompe à air - Hobbes et Boyle entre science et politique. Paris: La Découverte, 1993.

Thus, I do not think this proposition is worth entertaining. Not even for Bishop Berkeley, who is made into a caricature by many philosophers. Anticipating Samuel Johnson's famous refutation, he writes:

I do not argue against the existence of any one thing that we can apprehend either by sense or reflection. That the things I see with my eyes and touch with my hands do exist, really exist, I make not the least question. The only thing whose existence we deny is that which philosophers call Matter or corporeal substance. And in doing of this there is no damage done to the rest of mankind, who, I dare say, will never miss it.

George Berkeley, Treatise concerning Principles of Human Knowledge, §35, emphasis original


The answer depends entirely on how you wish to interpret the words matter and exist. In everyday use, the word exist has a much broader range of applications than the one you have in mind. Likewise, if your definition of matter is confined to objects that you can touch, then again your definition is a narrow one. On that basis, your proposition would be considered false by most people, I suspect. Some counter examples of entities most people would consider to exist even though they are not touchable objects...




Solutions to equations




etc etc


It's false since space and time, physical laws and minds exist. Furthermore one can say math exists. None of these are forms of matter.

  • Mozibur--great to see you again!! I hope you are well! Commented May 7 at 16:42
  • @Paradox Lost: Thxs, I am!! Commented May 8 at 8:39

The proposition was in dispute until Einstein’s relativity showed definitively that matter is not fundamental. Now we know the proposition is false.

The fallback, “do only physical things exist” is still currently in dispute today.

Also in dispute, and highly relevant to the truth of physicalism, is “what is it to be physical”? Most philosophers who are physicalists today admit to the existence of non material things, such as relationships, ideas, math, and experiences. Physics itself cannot be performed without these other things. Physics basically requires both Popper’s worlds 1 and 3. Many “physicalists” today even admit to the reality of world 2, and just insist that all causation run thru world 1(matter).

As I noted, whether these concessions and patches make physicalism possibly true or not is an ongoing debate in philosophy.

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