Are others conscious?
Summary
There is no way to know if anyone else is conscious.
Solipsism (/ˈsɒlɪpsɪzəm/; from Latin solus, meaning ‘alone’, and ipse, meaning ‘self’) is the philosophical idea that only one’s own mind is sure to exist.
While no great philosopher has explicitly espoused solipsism, this can be attributed to the inconsistency of much philosophical reasoning. Many philosophers have failed to accept the logical consequences of their own most fundamental commitments and preconceptions.
Internet Encyclopedia of Philosophy: Solipsism and the Problem of Other Minds
It is in principle impossible to know whether anyone else is conscious. It is impossible to know even whether anything exists beyond your own mind. The world could all just be your projection. This inconclusiveness is not a technological or scientific limitation. It cannot be resolved with more data.
Common criticisms tend to be along the lines of “but this world is more complex than anything I can imagine.” This is trivially countered: it is commonly the case that your nighttime dreams are more complex than your dream character believes he or she could produce. The dream character’s perspective is arising from the same mental source that gives rise to the dream, regardless of whether the character’s supposed mental faculties are dim or sharp.
If you cannot even be sure that other people exist, how can you be sure that they are conscious?