When everybody thinks alike, nobody will think at all.

The earliest close match located is an unattributed filler item printed in 1905 in a Philadelphia periodical (“The Westminster”). Later, similar phrasings were used by public figures (e.g., Walter Lippmann in 1915; Edward Krehbiel in 1919), which helped drive later attributions, but the specific wording “When everybody thinks alike, nobody will think at all” appears first as anonymous.

The line argues that uniform agreement in a group can suppress genuine reasoning: if no one challenges assumptions or offers different perspectives, the group stops actively thinking and simply conforms.

When everybody thinks alike there is hardly any incentive to think at all.

Where all think alike, no one thinks very much.

When everybody thinks alike nobody thinks at all.

If everyone is thinking alike then somebody isn’t thinking.