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\lhead{If a New Causal Chain Begins, a Non-Internal Contribution Exists}
\rhead{John C. W. McKinley}
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\newtheorem{proposition}{Proposition}
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\title{\textbf{If a New Causal Chain Begins, a Non-Internal Contribution Exists}
}
\author{John C. W. McKinley\,\orcidlink{0009-0005-7097-5035}
}
\date{April 24, 2026}
\begin{document}
\maketitle
\blfootnote{\scriptsize This version published at \url{https://doi.org/10.5281/zenodo.19752798}.}
\begin{abstract}
No closed physical system internally fixes the onset and direction of a new causal chain among multiple lawful possibilities.\cite{McKinley2026Closed} If a new causal chain nonetheless begins, then some contribution not contained within the closed physical description must exist. The claim concerns only the existence of such a contribution. It does not identify its ontology.
\end{abstract}
\section*{Statement}
The central thesis of this note is simple:
\begin{quote}
\textbf{Core Thesis.} The beginning of a new causal chain in a closed physical
system requires a non-internal contribution.
\end{quote}
Let $S(t)$ denote a closed physical state description of a system over some interval. Suppose that, at a definite moment $t^\ast$, a new causal chain begins and that more than one lawful continuation is available. Since no closed physical system internally fixes either the onset of that chain or its realized direction\cite{McKinley2026Closed}, the beginning of the chain requires some contribution not contained within $S(t)$.
\begin{definition}[Closed physical description]
A \emph{closed physical description} is a description containing only the laws, state-terms, and causal resources internal to the system under consideration.
\end{definition}
\begin{definition}[Non-internal contribution]
A \emph{non-internal contribution} is a contribution that is not contained within the closed physical description $S(t)$.
\end{definition}
\begin{proposition}[Existence of a non-internal contribution]
Since a closed physical description does not internally fix the onset and direction of
a new causal chain among multiple lawful possibilities, the beginning of such a chain
requires a non-internal contribution.
\end{proposition}
\begin{proof}
By hypothesis, a new causal chain begins at a definite moment and a particular lawful continuation is realized. By the closed-system initiation no-go,\cite{McKinley2026Closed} the closed physical description does not internally fix either the onset of that chain or its realized direction. Therefore the beginning of the chain is not fully supplied by the closed description alone. Since the chain nonetheless begins, some contribution not contained within the closed physical description must exist. Hence a non-internal contribution exists.
\end{proof}
\begin{remark}[Existence claim only]
The present note makes an existence claim only. It does not specify the nature, magnitude, persistence, or interpretation of the non-internal contribution whose existence follows from the beginning of the chain.
\end{remark}
\begin{remark}[Not a characterization]
To conclude that a non-internal contribution exists is not to determine whether it is best described as an initiating increment, a boundary contribution, or under some further characterization. Those questions lie beyond the scope of the present note.
\end{remark}
\begin{remark}[Dependence on the prior no-go]
This result is conditional on the prior no-go: No closed physical system internally fixes the onset and direction of a new causal chain among multiple lawful possibilities.\cite{McKinley2026Closed}
\end{remark}
\section*{Falsifier}
The claim of this note fails if either of the following is shown:
\begin{enumerate}
\item a closed physical description internally fixes the onset and direction of a new causal chain after all, or
\item a new causal chain begins even though nothing beyond the closed physical description contributes to its beginning.
\end{enumerate}
\section*{Conclusion}
Since a closed physical description does not internally fix the onset and direction
of a new causal chain among multiple lawful possibilities, the beginning of such a
chain requires some non-internal contribution.
\begin{thebibliography}{1}
\bibitem{McKinley2026Closed}
J. C. W. McKinley, \emph{No Closed Physical System Internally Fixes the Onset and Direction of a New Causal Chain: A Structural No-Go Result}, Zenodo (2026). DOI:\,\href{https://doi.org/10.5281/zenodo.19464780}{10.5281/zenodo.19464780}.
\end{thebibliography}
\end{document}