Speaking of scientific, Joscha, you of all people should know that one cannot prove a negative.
Indeed, you make the claim that LLMs can think.
Extraordinary claims require extraordinary evidence, as Carl Sagan observed. Thus, the onus is on you and others who make that claim to give evidence as to its veracity. The process of science then follows to test that that claim.
By inverting the demand you yourself are engaging in unscientific methods.
The claim that "LLMs cannot think" is unscientific, unless supported by a very difficult argument about non equivalence of causal structure producing anthropomorphic outputs. The claim requires a formally rigorous definition of thinking that captures how humans mentally manipulate conceptual structure. Since LLMs can reproduce all kinds of human output that require operations that are typically considered to involve thought (eg. scene understanding, text summarization, translation, computer programs, mathematical proofs, common sense arguments, spatial cognition, theory of mind), it has to be shown that LLMs reach these results in fundamentally different ways than human minds. In principle, this is not impossible (given that thinking is still relatively poorly understood by cognitive neuroscience), but would be surprising, because it has been shown that the causal structure of computer vision models is structurally equivalent to what neuroscience discovered about visual cognition in primates.
In any case, saying that LLMs don't think cannot reasonably mean that LLMs are inferior to human cognition (since that this evidently not true), but that LLMs discovered an equivalent yet at least equally powerful mechanism.