{"id":273379,"date":"2026-09-16T03:00:15","date_gmt":"2026-09-16T08:00:15","guid":{"rendered":"https:\/\/langcom.org\/?p=273379"},"modified":"2026-09-16T03:00:15","modified_gmt":"2026-09-16T08:00:15","slug":"modals-deduction-b1-b1","status":"publish","type":"post","link":"https:\/\/langcom.org\/fr\/blog\/modals-deduction-b1-b1\/","title":{"rendered":"B1 Modals of Deduction: Expressing Certainty and Possibility"},"content":{"rendered":"<div class=\"lc-answer\">Modals of deduction help us make educated guesses or conclusions about situations when we are not 100% sure. <strong>They allow you to express how certain you are about something happening now or in the future.<\/strong> Nous utilisons <span data-no-translation>must<\/span> when we are almost certain something is true, based on strong evidence. For example, <span data-no-translation>She looks tired, so she must be working hard.<\/span> When we think something is possible but not certain, we use <span data-no-translation>might<\/span>, <span data-no-translation>may<\/span>, ou <span data-no-translation>could<\/span>. Par exemple, <span data-no-translation>He isn&#8217;t answering, he might be busy.<\/span> Finally, if we are almost certain something is NOT true or impossible, we use <span data-no-translation>can&#8217;t<\/span>. An example is <span data-no-translation>That can&#8217;t be John, he&#8217;s on holiday.<\/span> These modals are essential for expressing probability in English conversations.<\/div>\n<h2>What Are Modals of Deduction?<\/h2>\n<p>Modals of deduction are special verbs that help us make guesses or draw conclusions about situations. We use them when we don&#8217;t have all the facts but can use evidence to decide how likely something is.<\/p>\n<p>These modals are different from modals of obligation (<span data-no-translation>must<\/span> for rules) or permission (<span data-no-translation>can<\/span> for ability). Here, they are about how certain you feel about a situation.<\/p>\n<div class=\"lc-cta lc-cta-blended\" style=\"border-radius:14px;padding:30px;margin:30px 0;text-align:center;color:#fff;background:linear-gradient(135deg,#0E63C4,#0A2540);\"><h3 style=\"color:#fff;font-size:22px;font-weight:800;margin:0 0 8px;\">\ud83c\udf93 Apprenez l'anglais gr\u00e2ce \u00e0 la m\u00e9thode mixte<\/h3><p style=\"margin:0 0 10px;opacity:.95;\">Petits groupes \u00b7 Tuteur IA disponible 24 h\/24, 7 j\/7 \u00b7 Pr\u00e9paration aux examens de Cambridge<\/p><p style=\"margin:0 0 16px;font-size:18px;\">Plans provenant de <strong><span class=\"woocommerce-Price-amount amount\"><bdi><span class=\"woocommerce-Price-currencySymbol\" translate=\"no\" dir=\"auto\">$<\/span>39<\/bdi><\/span><\/strong> <s style=\"opacity:.6;\"><span class=\"woocommerce-Price-amount amount\"><bdi><span class=\"woocommerce-Price-currencySymbol\" translate=\"no\" dir=\"auto\">$<\/span>79<\/bdi><\/span><\/s> par mois<\/p><a href=\"\/fr\/\" style=\"display:inline-block;margin-top:8px;padding:13px 30px;border-radius:8px;font-weight:700;text-decoration:none;background:#fff;color:#0E63C4;\">R\u00e9servez votre cours<\/a><\/div>\n<h2>How Do We Use <span data-no-translation>Must<\/span> for Certainty?<\/h2>\n<p>Nous utilisons <span data-no-translation>must<\/span> when we are almost 100% sure that something is true. We have strong evidence or a logical reason to believe it.<\/p>\n<ul>\n<li><strong>Signification :<\/strong> I am almost certain it is true.<\/li>\n<li><strong>Certainty Level:<\/strong> High (90-100%)<\/li>\n<li><strong>Structure:<\/strong> <span data-no-translation>Subject + must + base form of the verb<\/span><\/li>\n<\/ul>\n<h2>When Do We Use <span data-no-translation>Might<\/span>, <span data-no-translation>May<\/span>, et <span data-no-translation>Could<\/span> for Possibility?<\/h2>\n<p>Nous utilisons <span data-no-translation>might<\/span>, <span data-no-translation>may<\/span>, ou <span data-no-translation>could<\/span> when we think something is possible, but we are not very certain. They all have a similar meaning for deduction.<\/p>\n<ul>\n<li><strong>Signification :<\/strong> It is possible; I am not sure.<\/li>\n<li><strong>Certainty Level:<\/strong> Medium (30-70%)<\/li>\n<li><strong>Structure:<\/strong> <span data-no-translation>Subject + might\/may\/could + base form of the verb<\/span><\/li>\n<\/ul>\n<p><span data-no-translation>May<\/span> is sometimes considered slightly more formal than <span data-no-translation>might<\/span> ou <span data-no-translation>could<\/span>, but for deduction, they are often interchangeable.<\/p>\n<h2>How Do We Use <span data-no-translation>Can't<\/span> for Impossibility?<\/h2>\n<p>Nous utilisons <span data-no-translation>can't<\/span> when we are almost 100% sure that something is NOT true or impossible. We have strong evidence against it.<\/p>\n<ul>\n<li><strong>Signification :<\/strong> I am almost certain it is not true or impossible.<\/li>\n<li><strong>Certainty Level:<\/strong> Very Low (0-10%)<\/li>\n<li><strong>Structure:<\/strong> <span data-no-translation>Subject + can't + base form of the verb<\/span><\/li>\n<\/ul>\n<h2>Summarizing Certainty Levels<\/h2>\n<p>Here is a quick summary of the certainty levels for these modals:<\/p>\n<ul>\n<li><span data-no-translation><strong>Must<\/strong><\/span>: Almost 100% sure it's true.<\/li>\n<li><span data-no-translation><strong>Might \/ May \/ Could<\/strong><\/span>: Possible, but not certain (30-70% sure).<\/li>\n<li><span data-no-translation><strong>Can't<\/strong><\/span>: Almost 100% sure it's not true or impossible.<\/li>\n<\/ul>\n<table>\n<caption>Summary of Modals of Deduction and Certainty Levels<\/caption>\n<thead>\n<tr>\n<th>Modal Verb<\/th>\n<th>Meaning (Deduction)<\/th>\n<th>Certainty Level<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><span data-no-translation>Must<\/span><\/td>\n<td><span data-no-translation>Almost certain it is true<\/span><\/td>\n<td><span data-no-translation>High (90-100%)<\/span><\/td>\n<\/tr>\n<tr>\n<td><span data-no-translation>Might \/ May \/ Could<\/span><\/td>\n<td><span data-no-translation>It is possible, not certain<\/span><\/td>\n<td><span data-no-translation>Medium (30-70%)<\/span><\/td>\n<\/tr>\n<tr>\n<td><span data-no-translation>Can't<\/span><\/td>\n<td><span data-no-translation>Almost certain it is not true \/ impossible<\/span><\/td>\n<td><span data-no-translation>Very Low (0-10%)<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Exemples<\/h2>\n<ul>\n<li><span data-no-translation>The lights are off; they must be out.<\/span><\/li>\n<li><span data-no-translation>She's wearing a coat, so it must be cold outside.<\/span><\/li>\n<li><span data-no-translation>He hasn't arrived yet; he might be stuck in traffic.<\/span><\/li>\n<li><span data-no-translation>That could be Maria, but I'm not sure.<\/span><\/li>\n<li><span data-no-translation>It may rain later, so take an umbrella.<\/span><\/li>\n<li><span data-no-translation>You just ate; you can't be hungry already!<\/span><\/li>\n<li><span data-no-translation>That can't be his car; his is red.<\/span><\/li>\n<\/ul>\n<h2>Entra\u00eenement<\/h2>\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-1766\" class=\"h5p-iframe\" data-content-id=\"1766\" style=\"height:1px\" src=\"about:blank\" frameborder=\"0\" scrolling=\"no\" title=\"I10 L1 GRAMMAR Modals of deduction\"><\/iframe><\/div>\n<div class=\"lc-cta lc-cta-placement\" style=\"border-radius:14px;padding:30px;margin:30px 0;text-align:center;color:#fff;background:linear-gradient(135deg,#2B87DA,#29C4A9);\"><h3 style=\"color:#fff;font-size:22px;font-weight:800;margin:0 0 8px;\">\u270d\ufe0f Vous ne savez pas quel est votre niveau ?<\/h3><p style=\"margin:0 0 16px;opacity:.95;\">Passez notre test de niveau gratuit et recevez des commentaires personnalis\u00e9s de la part d'examinateurs certifi\u00e9s par Cambridge.<\/p><a href=\"\/fr\/anglais\/academie\/test-gratuit\/\" style=\"display:inline-block;margin-top:8px;padding:13px 30px;border-radius:8px;font-weight:700;text-decoration:none;background:#0A2540;color:#fff;\">Passez notre test de niveau GRATUIT<\/a><\/div>\n<h2>Erreurs courantes chez les hispanophones<\/h2>\n<p>Spanish speakers sometimes make specific mistakes with modals of deduction:<\/p>\n<ul>\n<li><strong>D\u00e9routant <span data-no-translation>must<\/span> for deduction with <span data-no-translation>must<\/span> for obligation:<\/strong> In Spanish, 'deber' can mean both. In English, <span data-no-translation>must<\/span> for deduction means 'I am almost certain', not 'it is necessary'.<br \/><em>Incorrect :<\/em> <span data-no-translation>You must study hard for the exam.<\/span> (Obligation)<br \/><em>Correct :<\/em> <span data-no-translation>She's always reading; she must love books.<\/span> (Deduction)<\/li>\n<li><strong>Utilisation de <span data-no-translation>mustn't<\/span> for negative deduction:<\/strong> <span data-no-translation>Mustn't<\/span> means 'it is forbidden' or 'you should not'. For negative deduction (it's impossible), always use <span data-no-translation>can't<\/span>.<br \/><em>Incorrect :<\/em> <span data-no-translation>That mustn't be true.<\/span><br \/><em>Correct :<\/em> <span data-no-translation>That can't be true.<\/span><\/li>\n<li><strong>Adding <span data-no-translation>maybe<\/span> before a modal of possibility:<\/strong> This is redundant because the modal already expresses possibility.<br \/><em>Incorrect :<\/em> <span data-no-translation>Maybe he might come later.<\/span><br \/><em>Correct :<\/em> <span data-no-translation>He might come later.<\/span><\/li>\n<\/ul>\n<h2>Questions fr\u00e9quemment pos\u00e9es<\/h2>\n<h3>What is the main difference between <span data-no-translation>might<\/span>, <span data-no-translation>may<\/span>, et <span data-no-translation>could<\/span> for deduction?<\/h3>\n<p>For deduction, <span data-no-translation>might<\/span>, <span data-no-translation>may<\/span>, et <span data-no-translation>could<\/span> are very similar and often interchangeable. They all express a possibility. <span data-no-translation>May<\/span> can be slightly more formal.<\/p>\n<h3>Can I use <span data-no-translation>mustn't<\/span> for negative deductions?<\/h3>\n<p>No. <span data-no-translation>Mustn't<\/span> means prohibition (e.g., <span data-no-translation>You mustn't smoke here.<\/span>). For negative deductions, meaning something is impossible or certainly not true, you must use <span data-no-translation>can't<\/span> (par exemple, <span data-no-translation>That can't be right.<\/span>).<\/p>\n<h3>Quelle est la diff\u00e9rence entre <span data-no-translation>must<\/span> (deduction) and <span data-no-translation>have to<\/span>?<\/h3>\n<p><span data-no-translation>Must<\/span> for deduction means you are almost certain something is true based on evidence (e.g., <span data-no-translation>He must be tired.<\/span>). <span data-no-translation>Have to<\/span> expresses obligation or necessity (e.g., <span data-no-translation>I have to go now.<\/span>).<\/p>\n<h2>Le\u00e7ons associ\u00e9es<\/h2>\n<ul>\n<li><a href=\"https:\/\/langcom.org\/fr\/?p=272776\">Modal verbs<\/a><\/li>\n<li><a href=\"https:\/\/langcom.org\/fr\/?p=273037\">Modal verbs<\/a><\/li>\n<li><a href=\"https:\/\/langcom.org\/fr\/?p=273133\">Modal verbs<\/a><\/li>\n<li><a href=\"https:\/\/langcom.org\/fr\/?p=273153\">Modal verbs<\/a><\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>Modals of deduction help us make educated guesses or conclusions about situations when we are not 100% sure. They allow you to express how certain you are about something happening now or in the future. We use must when we are almost certain something is true, based on strong evidence. For example, She looks tired, [&hellip;]<\/p>\n","protected":false},"author":192,"featured_media":274434,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"bwfblock_default_font":"","langcom_teaches":"Modal verbs","langcom_cefr":"B1","langcom_type":"grammar","langcom_faq":"[{\"q\": \"What is the main difference between <span data-no-translation>might<\/span>, <span data-no-translation>may<\/span>, and <span data-no-translation>could<\/span> for deduction?\", \"a\": \"For deduction, <span data-no-translation>might<\/span>, <span data-no-translation>may<\/span>, and <span data-no-translation>could<\/span> are very similar and often interchangeable. They all express a possibility. <span data-no-translation>May<\/span> can be slightly more formal.\"}, {\"q\": \"Can I use <span data-no-translation>mustn't<\/span> for negative deductions?\", \"a\": \"No. <span data-no-translation>Mustn't<\/span> means prohibition (e.g., <span data-no-translation>You mustn't smoke here.<\/span>). For negative deductions, meaning something is impossible or certainly not true, you must use <span data-no-translation>can't<\/span> (e.g., <span data-no-translation>That can't be right.<\/span>).\"}, {\"q\": \"What is the difference between <span data-no-translation>must<\/span> (deduction) and <span data-no-translation>have to<\/span>?\", \"a\": \"<span data-no-translation>Must<\/span> for deduction means you are almost certain something is true based on evidence (e.g., <span data-no-translation>He must be tired.<\/span>). <span data-no-translation>Have to<\/span> expresses obligation or necessity (e.g., <span data-no-translation>I have to go now.<\/span>).\"}]","_kiss_seo_title":"","_kiss_seo_excerpt":"Modals of deduction help us make educated guesses or conclusions about situations when we are not 100% 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